ndimiduk commented on a change in pull request #2584:
URL: https://github.com/apache/hbase/pull/2584#discussion_r516141572
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/RegionLocations.java
##########
@@ -86,6 +91,25 @@ public RegionLocations(HRegionLocation... locations) {
this.numNonNullElements = numNonNullElements;
}
+ /**
+ * Constructs the region location list. The locations array should
+ * contain all the locations for known replicas for the region, and should be
+ * sorted in replicaId ascending order, although it can contain nulls
indicating replicaIds
+ * that the locations of which are not known.
+ * @param locations an array of HRegionLocations for the same region range
+ */
+ public RegionLocations(HRegionLocation... locations) {
Review comment:
Is there value in verification the the replicaId order is correct? Or
maybe the caller is considered responsible/trustworthy.
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncNonMetaRegionLocator.java
##########
@@ -196,8 +202,43 @@ private boolean tryComplete(LocateRequest req,
CompletableFuture<RegionLocations
MAX_CONCURRENT_LOCATE_REQUEST_PER_TABLE,
DEFAULT_MAX_CONCURRENT_LOCATE_REQUEST_PER_TABLE);
this.locatePrefetchLimit =
conn.getConfiguration().getInt(LOCATE_PREFETCH_LIMIT,
DEFAULT_LOCATE_PREFETCH_LIMIT);
- this.useMetaReplicas =
- conn.getConfiguration().getBoolean(USE_META_REPLICAS,
DEFAULT_USE_META_REPLICAS);
+
+ // Get the region locator's meta replica mode.
+ this.metaReplicaMode = CatalogReplicaMode.valueOf(conn.getConfiguration()
+ .get(LOCATOR_META_REPLICAS_MODE, CatalogReplicaMode.None.toString()));
+
+ switch (this.metaReplicaMode) {
+ case LoadBalance:
+ String replicaSelectorClass = conn.getConfiguration().
Review comment:
It would be nice if you could encapsulate the logic of creating the
instance of `metaReplicaSelector` into a factory method.
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
##########
@@ -0,0 +1,293 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import static org.apache.hadoop.hbase.client.ConnectionUtils.isEmptyStopRow;
+import static org.apache.hadoop.hbase.util.Bytes.BYTES_COMPARATOR;
+import static org.apache.hadoop.hbase.util.ConcurrentMapUtils.computeIfAbsent;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.IntSupplier;
+import org.apache.commons.lang3.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.HRegionLocation;
+import org.apache.hadoop.hbase.ScheduledChore;
+import org.apache.hadoop.hbase.Stoppable;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>CatalogReplicaLoadBalanceReplicaSimpleSelector implements a simple
catalog replica load balancing
+ * algorithm. It maintains a stale location cache for each table. Whenever
client looks up location,
+ * it first check if the row is the stale location cache. If yes, the location
from
+ * catalog replica is stale, it will go to the primary region to look up
update-to-date location;
+ * otherwise, it will randomly pick up a replica region for lookup. When
clients receive
+ * RegionNotServedException from region servers, it will add these region
locations to the stale
+ * location cache. The stale cache will be cleaned up periodically by a
chore.</p>
+ *
+ * It follows a simple algorithm to choose a replica to go:
+ *
+ * <ol>
+ * <li>If there is no stale location entry for rows it looks up, it will
randomly
+ * pick a replica region to do lookup. </li>
+ * <li>If the location from the replica region is stale, client gets
RegionNotServedException
+ * from region server, in this case, it will create
StaleLocationCacheEntry in
+ * CatalogReplicaLoadBalanceReplicaSimpleSelector.</li>
+ * <li>When client tries to do location lookup, it checks StaleLocationCache
first for rows it
+ * tries to lookup, if entry exists, it will go with primary meta region
to do lookup;
+ * otherwise, it will follow step 1.</li>
+ * <li>A chore will periodically run to clean up cache entries in the
StaleLocationCache.</li>
+ * </ol>
+ */
+class CatalogReplicaLoadBalanceSimpleSelector implements
+ CatalogReplicaLoadBalanceSelector, Stoppable {
+ private static final Logger LOG =
+ LoggerFactory.getLogger(CatalogReplicaLoadBalanceSimpleSelector.class);
+ private final long STALE_CACHE_TIMEOUT_IN_MILLISECONDS = 3000; // 3 seconds
+ private final int STALE_CACHE_CLEAN_CHORE_INTERVAL_IN_MILLISECONDS = 1500;
// 1.5 seconds
+ private final int REFRESH_REPLICA_COUNT_CHORE_INTERVAL_IN_MILLISECONDS =
60000; // 1 minute
+
+ /**
+ * StaleLocationCacheEntry is the entry when a stale location is reported by
an client.
+ */
+ private static final class StaleLocationCacheEntry {
+ // timestamp in milliseconds
+ private final long timestamp;
+
+ private final byte[] endKey;
+
+ StaleLocationCacheEntry(final byte[] endKey) {
+ this.endKey = endKey;
+ timestamp = EnvironmentEdgeManager.currentTime();
+ }
+
+ public byte[] getEndKey() {
+ return this.endKey;
+ }
+
+ public long getTimestamp() {
+ return this.timestamp;
+ }
+
+ @Override
+ public String toString() {
+ return new ToStringBuilder(this)
+ .append("endKey", endKey)
+ .append("timestamp", timestamp)
+ .toString();
+ }
+ }
+
+ private final ConcurrentMap<TableName, ConcurrentNavigableMap<byte[],
StaleLocationCacheEntry>>
+ staleCache = new ConcurrentHashMap<>();
+ private volatile int numOfReplicas;
+ private final AsyncConnectionImpl conn;
+ private final TableName tableName;
+ private final IntSupplier getNumOfReplicas;
+ private volatile boolean isStopped = false;
+
+ CatalogReplicaLoadBalanceSimpleSelector(TableName tableName,
AsyncConnectionImpl conn,
+ IntSupplier getNumOfReplicas) {
+ this.conn = conn;
+ this.tableName = tableName;
+ this.getNumOfReplicas = getNumOfReplicas;
+
+ // This numOfReplicas is going to be lazy initialized.
+ this.numOfReplicas = -1;
+ // Start chores
+ this.conn.getChoreService().scheduleChore(getCacheCleanupChore(this));
+
this.conn.getChoreService().scheduleChore(getRefreshReplicaCountChore(this));
+ }
+
+ /**
+ * When a client runs into RegionNotServingException, it will call this
method to
Review comment:
Is this javadoc better placed on the interface method?
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
##########
@@ -0,0 +1,293 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import static org.apache.hadoop.hbase.client.ConnectionUtils.isEmptyStopRow;
+import static org.apache.hadoop.hbase.util.Bytes.BYTES_COMPARATOR;
+import static org.apache.hadoop.hbase.util.ConcurrentMapUtils.computeIfAbsent;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.IntSupplier;
+import org.apache.commons.lang3.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.HRegionLocation;
+import org.apache.hadoop.hbase.ScheduledChore;
+import org.apache.hadoop.hbase.Stoppable;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>CatalogReplicaLoadBalanceReplicaSimpleSelector implements a simple
catalog replica load balancing
+ * algorithm. It maintains a stale location cache for each table. Whenever
client looks up location,
+ * it first check if the row is the stale location cache. If yes, the location
from
+ * catalog replica is stale, it will go to the primary region to look up
update-to-date location;
+ * otherwise, it will randomly pick up a replica region for lookup. When
clients receive
+ * RegionNotServedException from region servers, it will add these region
locations to the stale
+ * location cache. The stale cache will be cleaned up periodically by a
chore.</p>
+ *
+ * It follows a simple algorithm to choose a replica to go:
+ *
+ * <ol>
+ * <li>If there is no stale location entry for rows it looks up, it will
randomly
+ * pick a replica region to do lookup. </li>
+ * <li>If the location from the replica region is stale, client gets
RegionNotServedException
+ * from region server, in this case, it will create
StaleLocationCacheEntry in
+ * CatalogReplicaLoadBalanceReplicaSimpleSelector.</li>
+ * <li>When client tries to do location lookup, it checks StaleLocationCache
first for rows it
+ * tries to lookup, if entry exists, it will go with primary meta region
to do lookup;
+ * otherwise, it will follow step 1.</li>
+ * <li>A chore will periodically run to clean up cache entries in the
StaleLocationCache.</li>
+ * </ol>
+ */
+class CatalogReplicaLoadBalanceSimpleSelector implements
+ CatalogReplicaLoadBalanceSelector, Stoppable {
+ private static final Logger LOG =
+ LoggerFactory.getLogger(CatalogReplicaLoadBalanceSimpleSelector.class);
+ private final long STALE_CACHE_TIMEOUT_IN_MILLISECONDS = 3000; // 3 seconds
+ private final int STALE_CACHE_CLEAN_CHORE_INTERVAL_IN_MILLISECONDS = 1500;
// 1.5 seconds
+ private final int REFRESH_REPLICA_COUNT_CHORE_INTERVAL_IN_MILLISECONDS =
60000; // 1 minute
+
+ /**
+ * StaleLocationCacheEntry is the entry when a stale location is reported by
an client.
+ */
+ private static final class StaleLocationCacheEntry {
+ // timestamp in milliseconds
+ private final long timestamp;
+
+ private final byte[] endKey;
+
+ StaleLocationCacheEntry(final byte[] endKey) {
+ this.endKey = endKey;
+ timestamp = EnvironmentEdgeManager.currentTime();
+ }
+
+ public byte[] getEndKey() {
+ return this.endKey;
+ }
+
+ public long getTimestamp() {
+ return this.timestamp;
+ }
+
+ @Override
+ public String toString() {
+ return new ToStringBuilder(this)
+ .append("endKey", endKey)
+ .append("timestamp", timestamp)
+ .toString();
+ }
+ }
+
+ private final ConcurrentMap<TableName, ConcurrentNavigableMap<byte[],
StaleLocationCacheEntry>>
+ staleCache = new ConcurrentHashMap<>();
+ private volatile int numOfReplicas;
+ private final AsyncConnectionImpl conn;
+ private final TableName tableName;
+ private final IntSupplier getNumOfReplicas;
+ private volatile boolean isStopped = false;
+
+ CatalogReplicaLoadBalanceSimpleSelector(TableName tableName,
AsyncConnectionImpl conn,
+ IntSupplier getNumOfReplicas) {
+ this.conn = conn;
+ this.tableName = tableName;
+ this.getNumOfReplicas = getNumOfReplicas;
+
+ // This numOfReplicas is going to be lazy initialized.
+ this.numOfReplicas = -1;
+ // Start chores
+ this.conn.getChoreService().scheduleChore(getCacheCleanupChore(this));
+
this.conn.getChoreService().scheduleChore(getRefreshReplicaCountChore(this));
+ }
+
+ /**
+ * When a client runs into RegionNotServingException, it will call this
method to
+ * update Selector's internal state.
+ * @param loc the location which causes exception.
+ */
+ public void onError(HRegionLocation loc) {
+ ConcurrentNavigableMap<byte[], StaleLocationCacheEntry> tableCache =
+ computeIfAbsent(staleCache, loc.getRegion().getTable(),
+ () -> new ConcurrentSkipListMap<>(BYTES_COMPARATOR));
+ byte[] startKey = loc.getRegion().getStartKey();
+ tableCache.putIfAbsent(startKey,
+ new StaleLocationCacheEntry(loc.getRegion().getEndKey()));
+ LOG.debug("Add entry to stale cache for table {} with startKey {}, {}",
+ loc.getRegion().getTable(), startKey, loc.getRegion().getEndKey());
+ }
+
+ /**
+ * Select an random replica id. In case there is no replica region
configured, return
+ * the primary replica id.
+ * @return Replica id
+ */
+ private int getRandomReplicaId() {
+ int cachedNumOfReplicas = this.numOfReplicas;
+ if (cachedNumOfReplicas < 0) {
+ cachedNumOfReplicas = refreshCatalogReplicaCount();
+ this.numOfReplicas = cachedNumOfReplicas;
+ }
+ // In case of no replica configured, return the primary region id.
+ if (cachedNumOfReplicas <= 1) {
+ return RegionInfo.DEFAULT_REPLICA_ID;
+ }
+ return 1 + ThreadLocalRandom.current().nextInt(cachedNumOfReplicas - 1);
+ }
+
+ /**
+ * When it looks up a location, it will call this method to find a replica
region to go.
Review comment:
Same question about putting this javadoc on the interface method instead
of on the implementation.
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncNonMetaRegionLocator.java
##########
@@ -196,8 +202,43 @@ private boolean tryComplete(LocateRequest req,
CompletableFuture<RegionLocations
MAX_CONCURRENT_LOCATE_REQUEST_PER_TABLE,
DEFAULT_MAX_CONCURRENT_LOCATE_REQUEST_PER_TABLE);
this.locatePrefetchLimit =
conn.getConfiguration().getInt(LOCATE_PREFETCH_LIMIT,
DEFAULT_LOCATE_PREFETCH_LIMIT);
- this.useMetaReplicas =
- conn.getConfiguration().getBoolean(USE_META_REPLICAS,
DEFAULT_USE_META_REPLICAS);
+
+ // Get the region locator's meta replica mode.
+ this.metaReplicaMode = CatalogReplicaMode.valueOf(conn.getConfiguration()
Review comment:
`valueOf` is rather strict for parsing user-provided values. See my
comment on the enum for a way to make this more user-friendly.
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncNonMetaRegionLocator.java
##########
@@ -82,14 +84,18 @@
static String LOCATE_PREFETCH_LIMIT = "hbase.client.locate.prefetch.limit";
private static final int DEFAULT_LOCATE_PREFETCH_LIMIT = 10;
+ private static final long GET_META_LOCATIONS_TIMEOUT = 2000; // 2 seconds
Review comment:
nit: please include a unit in the constant name. Doubly-so if this is
also a key used to look up a configuration value. Looks like this would be
`GET_META_LOCATIONS_TIMEOUT_MS`.
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncNonMetaRegionLocator.java
##########
@@ -196,8 +202,43 @@ private boolean tryComplete(LocateRequest req,
CompletableFuture<RegionLocations
MAX_CONCURRENT_LOCATE_REQUEST_PER_TABLE,
DEFAULT_MAX_CONCURRENT_LOCATE_REQUEST_PER_TABLE);
this.locatePrefetchLimit =
conn.getConfiguration().getInt(LOCATE_PREFETCH_LIMIT,
DEFAULT_LOCATE_PREFETCH_LIMIT);
- this.useMetaReplicas =
- conn.getConfiguration().getBoolean(USE_META_REPLICAS,
DEFAULT_USE_META_REPLICAS);
+
+ // Get the region locator's meta replica mode.
+ this.metaReplicaMode = CatalogReplicaMode.valueOf(conn.getConfiguration()
+ .get(LOCATOR_META_REPLICAS_MODE, CatalogReplicaMode.None.toString()));
+
+ switch (this.metaReplicaMode) {
+ case LoadBalance:
+ String replicaSelectorClass = conn.getConfiguration().
+ get(RegionLocator.LOCATOR_META_REPLICAS_MODE_LOADBALANCE_SELECTOR,
+ CatalogReplicaLoadBalanceSimpleSelector.class.getName());
+
+ this.metaReplicaSelector =
CatalogReplicaLoadBalanceSelectorFactory.createSelector(
+ replicaSelectorClass, META_TABLE_NAME, conn, () -> {
+ int numOfReplicas = 1;
+ try {
+ RegionLocations metaLocations =
conn.registry.getMetaRegionLocations().get(
+ GET_META_LOCATIONS_TIMEOUT, TimeUnit.MILLISECONDS);
+ numOfReplicas = metaLocations.size();
+ } catch (Exception e) {
+ LOG.error("Failed to get table {}'s region replication, ",
META_TABLE_NAME, e);
+ }
+ return numOfReplicas;
+ });
+ break;
+ case None:
+ // If user does not configure LOCATOR_META_REPLICAS_MODE, let's check
the legacy config.
+ if (this.metaReplicaMode == CatalogReplicaMode.None) {
Review comment:
Why the if-block? The `case None:` is already confirming that
`this.metaReplicaMode == CatalogReplicaMode.None)`
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
##########
@@ -0,0 +1,293 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import static org.apache.hadoop.hbase.client.ConnectionUtils.isEmptyStopRow;
+import static org.apache.hadoop.hbase.util.Bytes.BYTES_COMPARATOR;
+import static org.apache.hadoop.hbase.util.ConcurrentMapUtils.computeIfAbsent;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.IntSupplier;
+import org.apache.commons.lang3.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.HRegionLocation;
+import org.apache.hadoop.hbase.ScheduledChore;
+import org.apache.hadoop.hbase.Stoppable;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>CatalogReplicaLoadBalanceReplicaSimpleSelector implements a simple
catalog replica load balancing
+ * algorithm. It maintains a stale location cache for each table. Whenever
client looks up location,
+ * it first check if the row is the stale location cache. If yes, the location
from
+ * catalog replica is stale, it will go to the primary region to look up
update-to-date location;
+ * otherwise, it will randomly pick up a replica region for lookup. When
clients receive
+ * RegionNotServedException from region servers, it will add these region
locations to the stale
+ * location cache. The stale cache will be cleaned up periodically by a
chore.</p>
+ *
+ * It follows a simple algorithm to choose a replica to go:
+ *
+ * <ol>
+ * <li>If there is no stale location entry for rows it looks up, it will
randomly
+ * pick a replica region to do lookup. </li>
+ * <li>If the location from the replica region is stale, client gets
RegionNotServedException
+ * from region server, in this case, it will create
StaleLocationCacheEntry in
+ * CatalogReplicaLoadBalanceReplicaSimpleSelector.</li>
+ * <li>When client tries to do location lookup, it checks StaleLocationCache
first for rows it
+ * tries to lookup, if entry exists, it will go with primary meta region
to do lookup;
+ * otherwise, it will follow step 1.</li>
+ * <li>A chore will periodically run to clean up cache entries in the
StaleLocationCache.</li>
+ * </ol>
+ */
+class CatalogReplicaLoadBalanceSimpleSelector implements
+ CatalogReplicaLoadBalanceSelector, Stoppable {
+ private static final Logger LOG =
+ LoggerFactory.getLogger(CatalogReplicaLoadBalanceSimpleSelector.class);
+ private final long STALE_CACHE_TIMEOUT_IN_MILLISECONDS = 3000; // 3 seconds
+ private final int STALE_CACHE_CLEAN_CHORE_INTERVAL_IN_MILLISECONDS = 1500;
// 1.5 seconds
+ private final int REFRESH_REPLICA_COUNT_CHORE_INTERVAL_IN_MILLISECONDS =
60000; // 1 minute
+
+ /**
+ * StaleLocationCacheEntry is the entry when a stale location is reported by
an client.
+ */
+ private static final class StaleLocationCacheEntry {
+ // timestamp in milliseconds
+ private final long timestamp;
+
+ private final byte[] endKey;
+
+ StaleLocationCacheEntry(final byte[] endKey) {
+ this.endKey = endKey;
+ timestamp = EnvironmentEdgeManager.currentTime();
+ }
+
+ public byte[] getEndKey() {
+ return this.endKey;
+ }
+
+ public long getTimestamp() {
+ return this.timestamp;
+ }
+
+ @Override
+ public String toString() {
+ return new ToStringBuilder(this)
Review comment:
I think i mentioned this earlier as well -- please use the
`ShortPrefixToStringStyle`.
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncNonMetaRegionLocator.java
##########
@@ -444,6 +503,8 @@ private void locateInMeta(TableName tableName,
LocateRequest req) {
@Override
public void onError(Throwable error) {
+ // TODO: if it fails, with meta replica load balance, it may try with
another meta
Review comment:
Mention the jira or delete the TODO?
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
##########
@@ -0,0 +1,293 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import static org.apache.hadoop.hbase.client.ConnectionUtils.isEmptyStopRow;
+import static org.apache.hadoop.hbase.util.Bytes.BYTES_COMPARATOR;
+import static org.apache.hadoop.hbase.util.ConcurrentMapUtils.computeIfAbsent;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.IntSupplier;
+import org.apache.commons.lang3.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.HRegionLocation;
+import org.apache.hadoop.hbase.ScheduledChore;
+import org.apache.hadoop.hbase.Stoppable;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>CatalogReplicaLoadBalanceReplicaSimpleSelector implements a simple
catalog replica load balancing
+ * algorithm. It maintains a stale location cache for each table. Whenever
client looks up location,
+ * it first check if the row is the stale location cache. If yes, the location
from
+ * catalog replica is stale, it will go to the primary region to look up
update-to-date location;
+ * otherwise, it will randomly pick up a replica region for lookup. When
clients receive
+ * RegionNotServedException from region servers, it will add these region
locations to the stale
+ * location cache. The stale cache will be cleaned up periodically by a
chore.</p>
+ *
+ * It follows a simple algorithm to choose a replica to go:
+ *
+ * <ol>
+ * <li>If there is no stale location entry for rows it looks up, it will
randomly
+ * pick a replica region to do lookup. </li>
+ * <li>If the location from the replica region is stale, client gets
RegionNotServedException
+ * from region server, in this case, it will create
StaleLocationCacheEntry in
+ * CatalogReplicaLoadBalanceReplicaSimpleSelector.</li>
+ * <li>When client tries to do location lookup, it checks StaleLocationCache
first for rows it
+ * tries to lookup, if entry exists, it will go with primary meta region
to do lookup;
+ * otherwise, it will follow step 1.</li>
+ * <li>A chore will periodically run to clean up cache entries in the
StaleLocationCache.</li>
+ * </ol>
+ */
+class CatalogReplicaLoadBalanceSimpleSelector implements
+ CatalogReplicaLoadBalanceSelector, Stoppable {
+ private static final Logger LOG =
+ LoggerFactory.getLogger(CatalogReplicaLoadBalanceSimpleSelector.class);
+ private final long STALE_CACHE_TIMEOUT_IN_MILLISECONDS = 3000; // 3 seconds
+ private final int STALE_CACHE_CLEAN_CHORE_INTERVAL_IN_MILLISECONDS = 1500;
// 1.5 seconds
+ private final int REFRESH_REPLICA_COUNT_CHORE_INTERVAL_IN_MILLISECONDS =
60000; // 1 minute
+
+ /**
+ * StaleLocationCacheEntry is the entry when a stale location is reported by
an client.
+ */
+ private static final class StaleLocationCacheEntry {
+ // timestamp in milliseconds
+ private final long timestamp;
Review comment:
nit: did we talk about this? Why not use a rich type like
`java.time.Instant` instead of a simple `long`?
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
##########
@@ -0,0 +1,302 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import static org.apache.hadoop.hbase.client.ConnectionUtils.isEmptyStopRow;
+import static org.apache.hadoop.hbase.util.Bytes.BYTES_COMPARATOR;
+import static org.apache.hadoop.hbase.util.ConcurrentMapUtils.computeIfAbsent;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.IntSupplier;
+import org.apache.commons.lang3.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.HRegionLocation;
+import org.apache.hadoop.hbase.ScheduledChore;
+import org.apache.hadoop.hbase.Stoppable;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>CatalogReplicaLoadBalanceReplicaSimpleSelector implements a simple
catalog replica load balancing
+ * algorithm. It maintains a stale location cache for each table. Whenever
client looks up location,
+ * it first check if the row is the stale location cache. If yes, the location
from
+ * catalog replica is stale, it will go to the primary region to look up
update-to-date location;
+ * otherwise, it will randomly pick up a replica region for lookup. When
clients receive
+ * RegionNotServedException from region servers, it will add these region
locations to the stale
+ * location cache. The stale cache will be cleaned up periodically by a
chore.</p>
+ *
+ * It follows a simple algorithm to choose a replica to go:
+ *
+ * <ol>
+ * <li>If there is no stale location entry for rows it looks up, it will
randomly
+ * pick a replica region to do lookup. </li>
+ * <li>If the location from the replica region is stale, client gets
RegionNotServedException
+ * from region server, in this case, it will create
StaleLocationCacheEntry in
+ * CatalogReplicaLoadBalanceReplicaSimpleSelector.</li>
+ * <li>When client tries to do location lookup, it checks StaleLocationCache
first for rows it
+ * tries to lookup, if entry exists, it will go with primary meta region
to do lookup;
+ * otherwise, it will follow step 1.</li>
+ * <li>A chore will periodically run to clean up cache entries in the
StaleLocationCache.</li>
+ * </ol>
+ */
+class CatalogReplicaLoadBalanceSimpleSelector implements
+ CatalogReplicaLoadBalanceSelector, Stoppable {
+ private static final Logger LOG =
+ LoggerFactory.getLogger(CatalogReplicaLoadBalanceSimpleSelector.class);
+ private final long STALE_CACHE_TIMEOUT_IN_MILLISECONDS = 3000; // 3 seconds
+ private final int STALE_CACHE_CLEAN_CHORE_INTERVAL_IN_MILLISECONDS = 1500;
// 1.5 seconds
+ private final int REFRESH_REPLICA_COUNT_CHORE_INTERVAL_IN_MILLISECONDS =
60000; // 1 minute
+
+ /**
+ * StaleLocationCacheEntry is the entry when a stale location is reported by
an client.
+ */
+ private static final class StaleLocationCacheEntry {
+ // replica id where the stale location comes from.
+ private final int fromReplicaId;
+
+ // timestamp in milliseconds
+ private final long timestamp;
+
+ private final byte[] endKey;
+
+ StaleLocationCacheEntry(final int metaReplicaId, final byte[] endKey) {
+ this.fromReplicaId = metaReplicaId;
+ this.endKey = endKey;
+ timestamp = EnvironmentEdgeManager.currentTime();
+ }
+
+ public byte[] getEndKey() {
+ return this.endKey;
+ }
+
+ public int getFromReplicaId() {
+ return this.fromReplicaId;
+ }
+ public long getTimestamp() {
+ return this.timestamp;
+ }
+
+ @Override
+ public String toString() {
+ return new ToStringBuilder(this)
+ .append("endKey", endKey)
+ .append("fromReplicaId", fromReplicaId)
+ .append("timestamp", timestamp)
+ .toString();
+ }
+ }
+
+ private final ConcurrentMap<TableName, ConcurrentNavigableMap<byte[],
StaleLocationCacheEntry>>
+ staleCache = new ConcurrentHashMap<>();
+ private volatile int numOfReplicas;
+ private final AsyncConnectionImpl conn;
+ private final TableName tableName;
+ private final IntSupplier getNumOfReplicas;
+ private volatile boolean isStopped = false;
+
+ CatalogReplicaLoadBalanceSimpleSelector(TableName tableName,
AsyncConnectionImpl conn,
+ IntSupplier getNumOfReplicas) {
+ this.conn = conn;
+ this.tableName = tableName;
+ this.getNumOfReplicas = getNumOfReplicas;
+
+ // This numOfReplicas is going to be lazy initialized.
+ this.numOfReplicas = -1;
+ // Start chores
+ this.conn.getChoreService().scheduleChore(getCacheCleanupChore(this));
+
this.conn.getChoreService().scheduleChore(getRefreshReplicaCountChore(this));
+ }
+
+ /**
+ * When a client runs into RegionNotServingException, it will call this
method to
+ * update Selector's internal state.
+ * @param loc the location which causes exception.
+ * @param fromReplicaId the replica id where the stale location comes from.
+ */
+ public void onError(HRegionLocation loc, int fromReplicaId) {
+ ConcurrentNavigableMap<byte[], StaleLocationCacheEntry> tableCache =
+ computeIfAbsent(staleCache, loc.getRegion().getTable(),
+ () -> new ConcurrentSkipListMap<>(BYTES_COMPARATOR));
+ byte[] startKey = loc.getRegion().getStartKey();
+ tableCache.putIfAbsent(startKey,
+ new StaleLocationCacheEntry(fromReplicaId, loc.getRegion().getEndKey()));
+ LOG.debug("Add entry to stale cache for table {} with startKey {}, {}",
+ loc.getRegion().getTable(), startKey, loc.getRegion().getEndKey());
+ }
+
+ /**
+ * Select an random replica id. In case there is no replica region
configured, return
+ * the primary replica id.
+ * @return Replica id
+ */
+ private int getRandomReplicaId() {
+ int cachedNumOfReplicas = this.numOfReplicas;
+ if (cachedNumOfReplicas < 0) {
Review comment:
should this be `cachedNumOfReplicas < 1`?
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
##########
@@ -0,0 +1,293 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import static org.apache.hadoop.hbase.client.ConnectionUtils.isEmptyStopRow;
+import static org.apache.hadoop.hbase.util.Bytes.BYTES_COMPARATOR;
+import static org.apache.hadoop.hbase.util.ConcurrentMapUtils.computeIfAbsent;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.IntSupplier;
+import org.apache.commons.lang3.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.HRegionLocation;
+import org.apache.hadoop.hbase.ScheduledChore;
+import org.apache.hadoop.hbase.Stoppable;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>CatalogReplicaLoadBalanceReplicaSimpleSelector implements a simple
catalog replica load balancing
+ * algorithm. It maintains a stale location cache for each table. Whenever
client looks up location,
+ * it first check if the row is the stale location cache. If yes, the location
from
+ * catalog replica is stale, it will go to the primary region to look up
update-to-date location;
+ * otherwise, it will randomly pick up a replica region for lookup. When
clients receive
+ * RegionNotServedException from region servers, it will add these region
locations to the stale
+ * location cache. The stale cache will be cleaned up periodically by a
chore.</p>
+ *
+ * It follows a simple algorithm to choose a replica to go:
+ *
+ * <ol>
Review comment:
This is great, thank you!
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaMode.java
##########
@@ -0,0 +1,40 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import org.apache.yetus.audience.InterfaceAudience;
+
+/**
+ * There are two modes with catalog replica support.
Review comment:
nit: add formatting to this javadoc OR move the descriptions of the enum
members down onto the enum members themselves.
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
##########
@@ -0,0 +1,293 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import static org.apache.hadoop.hbase.client.ConnectionUtils.isEmptyStopRow;
+import static org.apache.hadoop.hbase.util.Bytes.BYTES_COMPARATOR;
+import static org.apache.hadoop.hbase.util.ConcurrentMapUtils.computeIfAbsent;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.IntSupplier;
+import org.apache.commons.lang3.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.HRegionLocation;
+import org.apache.hadoop.hbase.ScheduledChore;
+import org.apache.hadoop.hbase.Stoppable;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>CatalogReplicaLoadBalanceReplicaSimpleSelector implements a simple
catalog replica load balancing
+ * algorithm. It maintains a stale location cache for each table. Whenever
client looks up location,
+ * it first check if the row is the stale location cache. If yes, the location
from
+ * catalog replica is stale, it will go to the primary region to look up
update-to-date location;
+ * otherwise, it will randomly pick up a replica region for lookup. When
clients receive
+ * RegionNotServedException from region servers, it will add these region
locations to the stale
+ * location cache. The stale cache will be cleaned up periodically by a
chore.</p>
+ *
+ * It follows a simple algorithm to choose a replica to go:
+ *
+ * <ol>
+ * <li>If there is no stale location entry for rows it looks up, it will
randomly
+ * pick a replica region to do lookup. </li>
+ * <li>If the location from the replica region is stale, client gets
RegionNotServedException
+ * from region server, in this case, it will create
StaleLocationCacheEntry in
+ * CatalogReplicaLoadBalanceReplicaSimpleSelector.</li>
+ * <li>When client tries to do location lookup, it checks StaleLocationCache
first for rows it
+ * tries to lookup, if entry exists, it will go with primary meta region
to do lookup;
+ * otherwise, it will follow step 1.</li>
+ * <li>A chore will periodically run to clean up cache entries in the
StaleLocationCache.</li>
+ * </ol>
+ */
+class CatalogReplicaLoadBalanceSimpleSelector implements
+ CatalogReplicaLoadBalanceSelector, Stoppable {
+ private static final Logger LOG =
+ LoggerFactory.getLogger(CatalogReplicaLoadBalanceSimpleSelector.class);
+ private final long STALE_CACHE_TIMEOUT_IN_MILLISECONDS = 3000; // 3 seconds
+ private final int STALE_CACHE_CLEAN_CHORE_INTERVAL_IN_MILLISECONDS = 1500;
// 1.5 seconds
+ private final int REFRESH_REPLICA_COUNT_CHORE_INTERVAL_IN_MILLISECONDS =
60000; // 1 minute
+
+ /**
+ * StaleLocationCacheEntry is the entry when a stale location is reported by
an client.
+ */
+ private static final class StaleLocationCacheEntry {
+ // timestamp in milliseconds
+ private final long timestamp;
+
+ private final byte[] endKey;
+
+ StaleLocationCacheEntry(final byte[] endKey) {
+ this.endKey = endKey;
+ timestamp = EnvironmentEdgeManager.currentTime();
+ }
+
+ public byte[] getEndKey() {
+ return this.endKey;
+ }
+
+ public long getTimestamp() {
+ return this.timestamp;
+ }
+
+ @Override
+ public String toString() {
+ return new ToStringBuilder(this)
+ .append("endKey", endKey)
+ .append("timestamp", timestamp)
+ .toString();
+ }
+ }
+
+ private final ConcurrentMap<TableName, ConcurrentNavigableMap<byte[],
StaleLocationCacheEntry>>
+ staleCache = new ConcurrentHashMap<>();
+ private volatile int numOfReplicas;
+ private final AsyncConnectionImpl conn;
+ private final TableName tableName;
+ private final IntSupplier getNumOfReplicas;
+ private volatile boolean isStopped = false;
+
+ CatalogReplicaLoadBalanceSimpleSelector(TableName tableName,
AsyncConnectionImpl conn,
+ IntSupplier getNumOfReplicas) {
+ this.conn = conn;
+ this.tableName = tableName;
+ this.getNumOfReplicas = getNumOfReplicas;
+
+ // This numOfReplicas is going to be lazy initialized.
+ this.numOfReplicas = -1;
+ // Start chores
+ this.conn.getChoreService().scheduleChore(getCacheCleanupChore(this));
+
this.conn.getChoreService().scheduleChore(getRefreshReplicaCountChore(this));
+ }
+
+ /**
+ * When a client runs into RegionNotServingException, it will call this
method to
+ * update Selector's internal state.
+ * @param loc the location which causes exception.
+ */
+ public void onError(HRegionLocation loc) {
+ ConcurrentNavigableMap<byte[], StaleLocationCacheEntry> tableCache =
+ computeIfAbsent(staleCache, loc.getRegion().getTable(),
+ () -> new ConcurrentSkipListMap<>(BYTES_COMPARATOR));
+ byte[] startKey = loc.getRegion().getStartKey();
+ tableCache.putIfAbsent(startKey,
+ new StaleLocationCacheEntry(loc.getRegion().getEndKey()));
+ LOG.debug("Add entry to stale cache for table {} with startKey {}, {}",
+ loc.getRegion().getTable(), startKey, loc.getRegion().getEndKey());
+ }
+
+ /**
+ * Select an random replica id. In case there is no replica region
configured, return
+ * the primary replica id.
+ * @return Replica id
+ */
+ private int getRandomReplicaId() {
+ int cachedNumOfReplicas = this.numOfReplicas;
+ if (cachedNumOfReplicas < 0) {
+ cachedNumOfReplicas = refreshCatalogReplicaCount();
+ this.numOfReplicas = cachedNumOfReplicas;
+ }
+ // In case of no replica configured, return the primary region id.
+ if (cachedNumOfReplicas <= 1) {
+ return RegionInfo.DEFAULT_REPLICA_ID;
+ }
+ return 1 + ThreadLocalRandom.current().nextInt(cachedNumOfReplicas - 1);
+ }
+
+ /**
+ * When it looks up a location, it will call this method to find a replica
region to go.
+ * For a normal case, > 99% of region locations from catalog/meta replica
will be up to date.
+ * In extreme cases such as region server crashes, it will depends on how
fast replication
+ * catches up.
+ *
+ * @param tablename table name it looks up
+ * @param row key it looks up.
+ * @param locateType locateType, Only BEFORE and CURRENT will be passed in.
+ * @return catalog replica id
+ */
+ public int select(final TableName tablename, final byte[] row,
+ final RegionLocateType locateType) {
+ ConcurrentNavigableMap<byte[], StaleLocationCacheEntry> tableCache =
staleCache.get(tablename);
+
+ // If there is no entry in StaleCache, select a random replica id.
+ if (tableCache == null) {
+ return getRandomReplicaId();
+ }
+
+ Map.Entry<byte[], StaleLocationCacheEntry> entry;
+ boolean isEmptyStopRow = isEmptyStopRow(row);
+ // Only BEFORE and CURRENT are passed in.
Review comment:
Still, I prefer to start my method with a `Precondition` and to use a
`switch` statement for enum-based branching, and then throw a "should not
happen" runtime exception, as i described earlier.
##########
File path:
hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestAsyncNonMetaRegionLocator.java
##########
@@ -55,35 +58,53 @@
import org.junit.ClassRule;
import org.junit.Test;
import org.junit.experimental.categories.Category;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
@Category({ MediumTests.class, ClientTests.class })
+@RunWith(Parameterized.class)
Review comment:
Ah, hey, you made it work! Thank you. I don't know if it works better
for you or not, but there's also `MiniClusterRule` in hbase-server.
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaMode.java
##########
@@ -0,0 +1,40 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import org.apache.yetus.audience.InterfaceAudience;
+
+/**
+ * There are two modes with catalog replica support.
+ *
+ * HedgedRead - Client sends requests to the primary region first, within a
+ * configured amount of time, if there is no response coming
back,
+ * client sends requests to all replica regions and takes the
first
+ * response.
+ *
+ * LoadBalance - Client sends requests to replica regions in a round-robin
mode,
+ * if results from replica regions are stale, next time,
client sends requests for
+ * these stale locations to the primary region. In this mode,
scan
+ * requests are load balanced across all replica regions.
+ */
[email protected]
+enum CatalogReplicaMode {
Review comment:
`Enum#valueOf` is case sensitive. For something like a user-facing
configuration, I prefer to make it more flexible. I Like the pattern that
Jersey defines around [Param
parsing](https://eclipse-ee4j.github.io/jersey.github.io/documentation/latest/jaxrs-resources.html#d0e2274),
which is to say that I like to implement a `fromString` method on my types
that adds the generous parsing logic. In this case, i think you'd want to
support case-insensitivity (at the very least), and possibly camel-case as well.
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
##########
@@ -0,0 +1,302 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import static org.apache.hadoop.hbase.client.ConnectionUtils.isEmptyStopRow;
+import static org.apache.hadoop.hbase.util.Bytes.BYTES_COMPARATOR;
+import static org.apache.hadoop.hbase.util.ConcurrentMapUtils.computeIfAbsent;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.IntSupplier;
+import org.apache.commons.lang3.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.HRegionLocation;
+import org.apache.hadoop.hbase.ScheduledChore;
+import org.apache.hadoop.hbase.Stoppable;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>CatalogReplicaLoadBalanceReplicaSimpleSelector implements a simple
catalog replica load balancing
+ * algorithm. It maintains a stale location cache for each table. Whenever
client looks up location,
+ * it first check if the row is the stale location cache. If yes, the location
from
+ * catalog replica is stale, it will go to the primary region to look up
update-to-date location;
+ * otherwise, it will randomly pick up a replica region for lookup. When
clients receive
+ * RegionNotServedException from region servers, it will add these region
locations to the stale
+ * location cache. The stale cache will be cleaned up periodically by a
chore.</p>
+ *
+ * It follows a simple algorithm to choose a replica to go:
+ *
+ * <ol>
+ * <li>If there is no stale location entry for rows it looks up, it will
randomly
+ * pick a replica region to do lookup. </li>
+ * <li>If the location from the replica region is stale, client gets
RegionNotServedException
+ * from region server, in this case, it will create
StaleLocationCacheEntry in
+ * CatalogReplicaLoadBalanceReplicaSimpleSelector.</li>
+ * <li>When client tries to do location lookup, it checks StaleLocationCache
first for rows it
+ * tries to lookup, if entry exists, it will go with primary meta region
to do lookup;
+ * otherwise, it will follow step 1.</li>
+ * <li>A chore will periodically run to clean up cache entries in the
StaleLocationCache.</li>
+ * </ol>
+ */
+class CatalogReplicaLoadBalanceSimpleSelector implements
+ CatalogReplicaLoadBalanceSelector, Stoppable {
+ private static final Logger LOG =
+ LoggerFactory.getLogger(CatalogReplicaLoadBalanceSimpleSelector.class);
+ private final long STALE_CACHE_TIMEOUT_IN_MILLISECONDS = 3000; // 3 seconds
+ private final int STALE_CACHE_CLEAN_CHORE_INTERVAL_IN_MILLISECONDS = 1500;
// 1.5 seconds
+ private final int REFRESH_REPLICA_COUNT_CHORE_INTERVAL_IN_MILLISECONDS =
60000; // 1 minute
+
+ /**
+ * StaleLocationCacheEntry is the entry when a stale location is reported by
an client.
+ */
+ private static final class StaleLocationCacheEntry {
+ // replica id where the stale location comes from.
+ private final int fromReplicaId;
+
+ // timestamp in milliseconds
+ private final long timestamp;
+
+ private final byte[] endKey;
+
+ StaleLocationCacheEntry(final int metaReplicaId, final byte[] endKey) {
+ this.fromReplicaId = metaReplicaId;
+ this.endKey = endKey;
+ timestamp = EnvironmentEdgeManager.currentTime();
+ }
+
+ public byte[] getEndKey() {
+ return this.endKey;
+ }
+
+ public int getFromReplicaId() {
+ return this.fromReplicaId;
+ }
+ public long getTimestamp() {
+ return this.timestamp;
+ }
+
+ @Override
+ public String toString() {
+ return new ToStringBuilder(this)
+ .append("endKey", endKey)
+ .append("fromReplicaId", fromReplicaId)
+ .append("timestamp", timestamp)
+ .toString();
+ }
+ }
+
+ private final ConcurrentMap<TableName, ConcurrentNavigableMap<byte[],
StaleLocationCacheEntry>>
+ staleCache = new ConcurrentHashMap<>();
+ private volatile int numOfReplicas;
+ private final AsyncConnectionImpl conn;
+ private final TableName tableName;
+ private final IntSupplier getNumOfReplicas;
+ private volatile boolean isStopped = false;
+
+ CatalogReplicaLoadBalanceSimpleSelector(TableName tableName,
AsyncConnectionImpl conn,
+ IntSupplier getNumOfReplicas) {
+ this.conn = conn;
+ this.tableName = tableName;
+ this.getNumOfReplicas = getNumOfReplicas;
+
+ // This numOfReplicas is going to be lazy initialized.
+ this.numOfReplicas = -1;
+ // Start chores
+ this.conn.getChoreService().scheduleChore(getCacheCleanupChore(this));
+
this.conn.getChoreService().scheduleChore(getRefreshReplicaCountChore(this));
+ }
+
+ /**
+ * When a client runs into RegionNotServingException, it will call this
method to
+ * update Selector's internal state.
+ * @param loc the location which causes exception.
+ * @param fromReplicaId the replica id where the stale location comes from.
+ */
+ public void onError(HRegionLocation loc, int fromReplicaId) {
+ ConcurrentNavigableMap<byte[], StaleLocationCacheEntry> tableCache =
+ computeIfAbsent(staleCache, loc.getRegion().getTable(),
+ () -> new ConcurrentSkipListMap<>(BYTES_COMPARATOR));
+ byte[] startKey = loc.getRegion().getStartKey();
+ tableCache.putIfAbsent(startKey,
+ new StaleLocationCacheEntry(fromReplicaId, loc.getRegion().getEndKey()));
+ LOG.debug("Add entry to stale cache for table {} with startKey {}, {}",
+ loc.getRegion().getTable(), startKey, loc.getRegion().getEndKey());
+ }
+
+ /**
+ * Select an random replica id. In case there is no replica region
configured, return
+ * the primary replica id.
+ * @return Replica id
+ */
+ private int getRandomReplicaId() {
+ int cachedNumOfReplicas = this.numOfReplicas;
+ if (cachedNumOfReplicas < 0) {
Review comment:
Oh I see, your uninitialized value is `-1`. Maybe instead define and
compare against an obvious constant, like `final int UNINITIALIZED =
Integer.MIN_VALUE`. Checking that the value is `< 0` is confusing for a
variable that holds a "count".
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncNonMetaRegionLocator.java
##########
@@ -196,8 +202,43 @@ private boolean tryComplete(LocateRequest req,
CompletableFuture<RegionLocations
MAX_CONCURRENT_LOCATE_REQUEST_PER_TABLE,
DEFAULT_MAX_CONCURRENT_LOCATE_REQUEST_PER_TABLE);
this.locatePrefetchLimit =
conn.getConfiguration().getInt(LOCATE_PREFETCH_LIMIT,
DEFAULT_LOCATE_PREFETCH_LIMIT);
- this.useMetaReplicas =
- conn.getConfiguration().getBoolean(USE_META_REPLICAS,
DEFAULT_USE_META_REPLICAS);
+
+ // Get the region locator's meta replica mode.
+ this.metaReplicaMode = CatalogReplicaMode.valueOf(conn.getConfiguration()
+ .get(LOCATOR_META_REPLICAS_MODE, CatalogReplicaMode.None.toString()));
+
+ switch (this.metaReplicaMode) {
+ case LoadBalance:
+ String replicaSelectorClass = conn.getConfiguration().
+ get(RegionLocator.LOCATOR_META_REPLICAS_MODE_LOADBALANCE_SELECTOR,
+ CatalogReplicaLoadBalanceSimpleSelector.class.getName());
+
+ this.metaReplicaSelector =
CatalogReplicaLoadBalanceSelectorFactory.createSelector(
+ replicaSelectorClass, META_TABLE_NAME, conn, () -> {
+ int numOfReplicas = 1;
+ try {
+ RegionLocations metaLocations =
conn.registry.getMetaRegionLocations().get(
+ GET_META_LOCATIONS_TIMEOUT, TimeUnit.MILLISECONDS);
+ numOfReplicas = metaLocations.size();
+ } catch (Exception e) {
+ LOG.error("Failed to get table {}'s region replication, ",
META_TABLE_NAME, e);
+ }
+ return numOfReplicas;
+ });
+ break;
+ case None:
+ // If user does not configure LOCATOR_META_REPLICAS_MODE, let's check
the legacy config.
+ if (this.metaReplicaMode == CatalogReplicaMode.None) {
+ boolean useMetaReplicas =
conn.getConfiguration().getBoolean(USE_META_REPLICAS,
+ DEFAULT_USE_META_REPLICAS);
+ if (useMetaReplicas) {
+ this.metaReplicaMode = CatalogReplicaMode.HedgedRead;
+ }
+ }
+ break;
+ default:
+ // Doing nothing
Review comment:
When a `switch` is intended to be exhaustive, I like to add `default:
throw new RuntimeException("should not happen");` If you don't like this, maybe
make `default` the same behavior as `None`.
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
##########
@@ -0,0 +1,293 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import static org.apache.hadoop.hbase.client.ConnectionUtils.isEmptyStopRow;
+import static org.apache.hadoop.hbase.util.Bytes.BYTES_COMPARATOR;
+import static org.apache.hadoop.hbase.util.ConcurrentMapUtils.computeIfAbsent;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.IntSupplier;
+import org.apache.commons.lang3.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.HRegionLocation;
+import org.apache.hadoop.hbase.ScheduledChore;
+import org.apache.hadoop.hbase.Stoppable;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>CatalogReplicaLoadBalanceReplicaSimpleSelector implements a simple
catalog replica load balancing
+ * algorithm. It maintains a stale location cache for each table. Whenever
client looks up location,
+ * it first check if the row is the stale location cache. If yes, the location
from
+ * catalog replica is stale, it will go to the primary region to look up
update-to-date location;
+ * otherwise, it will randomly pick up a replica region for lookup. When
clients receive
+ * RegionNotServedException from region servers, it will add these region
locations to the stale
+ * location cache. The stale cache will be cleaned up periodically by a
chore.</p>
+ *
+ * It follows a simple algorithm to choose a replica to go:
+ *
+ * <ol>
+ * <li>If there is no stale location entry for rows it looks up, it will
randomly
+ * pick a replica region to do lookup. </li>
+ * <li>If the location from the replica region is stale, client gets
RegionNotServedException
+ * from region server, in this case, it will create
StaleLocationCacheEntry in
+ * CatalogReplicaLoadBalanceReplicaSimpleSelector.</li>
+ * <li>When client tries to do location lookup, it checks StaleLocationCache
first for rows it
+ * tries to lookup, if entry exists, it will go with primary meta region
to do lookup;
+ * otherwise, it will follow step 1.</li>
+ * <li>A chore will periodically run to clean up cache entries in the
StaleLocationCache.</li>
+ * </ol>
+ */
+class CatalogReplicaLoadBalanceSimpleSelector implements
+ CatalogReplicaLoadBalanceSelector, Stoppable {
+ private static final Logger LOG =
+ LoggerFactory.getLogger(CatalogReplicaLoadBalanceSimpleSelector.class);
+ private final long STALE_CACHE_TIMEOUT_IN_MILLISECONDS = 3000; // 3 seconds
+ private final int STALE_CACHE_CLEAN_CHORE_INTERVAL_IN_MILLISECONDS = 1500;
// 1.5 seconds
+ private final int REFRESH_REPLICA_COUNT_CHORE_INTERVAL_IN_MILLISECONDS =
60000; // 1 minute
+
+ /**
+ * StaleLocationCacheEntry is the entry when a stale location is reported by
an client.
+ */
+ private static final class StaleLocationCacheEntry {
+ // timestamp in milliseconds
+ private final long timestamp;
+
+ private final byte[] endKey;
+
+ StaleLocationCacheEntry(final byte[] endKey) {
+ this.endKey = endKey;
+ timestamp = EnvironmentEdgeManager.currentTime();
+ }
+
+ public byte[] getEndKey() {
+ return this.endKey;
+ }
+
+ public long getTimestamp() {
+ return this.timestamp;
+ }
+
+ @Override
+ public String toString() {
+ return new ToStringBuilder(this)
+ .append("endKey", endKey)
+ .append("timestamp", timestamp)
+ .toString();
+ }
+ }
+
+ private final ConcurrentMap<TableName, ConcurrentNavigableMap<byte[],
StaleLocationCacheEntry>>
+ staleCache = new ConcurrentHashMap<>();
+ private volatile int numOfReplicas;
+ private final AsyncConnectionImpl conn;
+ private final TableName tableName;
+ private final IntSupplier getNumOfReplicas;
+ private volatile boolean isStopped = false;
+
+ CatalogReplicaLoadBalanceSimpleSelector(TableName tableName,
AsyncConnectionImpl conn,
+ IntSupplier getNumOfReplicas) {
+ this.conn = conn;
+ this.tableName = tableName;
+ this.getNumOfReplicas = getNumOfReplicas;
+
+ // This numOfReplicas is going to be lazy initialized.
+ this.numOfReplicas = -1;
+ // Start chores
+ this.conn.getChoreService().scheduleChore(getCacheCleanupChore(this));
+
this.conn.getChoreService().scheduleChore(getRefreshReplicaCountChore(this));
+ }
+
+ /**
+ * When a client runs into RegionNotServingException, it will call this
method to
+ * update Selector's internal state.
+ * @param loc the location which causes exception.
+ */
+ public void onError(HRegionLocation loc) {
+ ConcurrentNavigableMap<byte[], StaleLocationCacheEntry> tableCache =
+ computeIfAbsent(staleCache, loc.getRegion().getTable(),
+ () -> new ConcurrentSkipListMap<>(BYTES_COMPARATOR));
+ byte[] startKey = loc.getRegion().getStartKey();
+ tableCache.putIfAbsent(startKey,
+ new StaleLocationCacheEntry(loc.getRegion().getEndKey()));
+ LOG.debug("Add entry to stale cache for table {} with startKey {}, {}",
+ loc.getRegion().getTable(), startKey, loc.getRegion().getEndKey());
+ }
+
+ /**
+ * Select an random replica id. In case there is no replica region
configured, return
+ * the primary replica id.
+ * @return Replica id
+ */
+ private int getRandomReplicaId() {
+ int cachedNumOfReplicas = this.numOfReplicas;
+ if (cachedNumOfReplicas < 0) {
+ cachedNumOfReplicas = refreshCatalogReplicaCount();
+ this.numOfReplicas = cachedNumOfReplicas;
+ }
+ // In case of no replica configured, return the primary region id.
+ if (cachedNumOfReplicas <= 1) {
+ return RegionInfo.DEFAULT_REPLICA_ID;
+ }
+ return 1 + ThreadLocalRandom.current().nextInt(cachedNumOfReplicas - 1);
+ }
+
+ /**
+ * When it looks up a location, it will call this method to find a replica
region to go.
+ * For a normal case, > 99% of region locations from catalog/meta replica
will be up to date.
+ * In extreme cases such as region server crashes, it will depends on how
fast replication
+ * catches up.
+ *
+ * @param tablename table name it looks up
+ * @param row key it looks up.
+ * @param locateType locateType, Only BEFORE and CURRENT will be passed in.
+ * @return catalog replica id
+ */
+ public int select(final TableName tablename, final byte[] row,
+ final RegionLocateType locateType) {
+ ConcurrentNavigableMap<byte[], StaleLocationCacheEntry> tableCache =
staleCache.get(tablename);
+
+ // If there is no entry in StaleCache, select a random replica id.
+ if (tableCache == null) {
+ return getRandomReplicaId();
+ }
+
+ Map.Entry<byte[], StaleLocationCacheEntry> entry;
+ boolean isEmptyStopRow = isEmptyStopRow(row);
+ // Only BEFORE and CURRENT are passed in.
Review comment:
I agree it's redundant. I prefer to throw in the `default:` case because
it makes for an explicitly exhaustive switch statement, a feature from other
languages that I appreciate.
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