bharathv commented on a change in pull request #2643:
URL: https://github.com/apache/hbase/pull/2643#discussion_r524439773
##########
File path:
hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/ReplicationSourceManager.java
##########
@@ -1154,4 +1181,68 @@ int activeFailoverTaskCount() {
MetricsReplicationGlobalSourceSource getGlobalMetrics() {
return this.globalMetrics;
}
+
+ /**
+ * Add an hbase:meta Catalog replication source. Called on open of an
hbase:meta Region.
+ * Create it once only. If exists already, use the existing one.
+ * @see #removeCatalogReplicationSource(RegionInfo)
+ * @see #addSource(String) This is specialization on the addSource method.
+ */
+ public ReplicationSourceInterface addCatalogReplicationSource(RegionInfo
regionInfo)
+ throws IOException {
+ // Poor-man's putIfAbsent
+ synchronized (this.catalogReplicationSource) {
+ ReplicationSourceInterface rs = this.catalogReplicationSource.get();
+ return rs != null ? rs :
+
this.catalogReplicationSource.getAndSet(createCatalogReplicationSource(regionInfo));
+ }
+ }
+
+ /**
+ * Remove the hbase:meta Catalog replication source.
+ * Called when we close hbase:meta.
+ * @see #addCatalogReplicationSource(RegionInfo regionInfo)
+ */
+ public void removeCatalogReplicationSource(RegionInfo regionInfo) {
+ // Nothing to do. Leave any CatalogReplicationSource in place in case an
hbase:meta Region
+ // comes back to this server.
+ }
+
+ /**
+ * Create, initialize, and start the Catalog ReplicationSource.
+ * Presumes called one-time only (caller must ensure one-time only call).
+ * @see #addSource(String) This is a specialization of the addSource call.
+ */
+ private ReplicationSourceInterface createCatalogReplicationSource(RegionInfo
regionInfo)
+ throws IOException {
+ // Instantiate meta walProvider. Instantiated here or over in the
#warmupRegion call made by the
+ // Master on a 'move' operation. Need to do extra work if we did NOT
instantiate the provider.
+ WALProvider walProvider = this.walFactory.getMetaWALProvider();
+ boolean instantiate = walProvider == null;
+ if (instantiate) {
+ walProvider = this.walFactory.getMetaProvider();
+ }
+ CatalogReplicationSourcePeer peer = new
CatalogReplicationSourcePeer(this.conf,
+ this.clusterId.toString(), "meta_" +
ServerRegionReplicaUtil.REGION_REPLICA_REPLICATION_PEER);
+ final ReplicationSourceInterface crs = new CatalogReplicationSource();
+ crs.init(conf, fs, this, new NoopReplicationQueueStorage(), peer, server,
peer.getId(),
Review comment:
nit: This could use a comment as it might not be obvious to the reader
why ZK checkpointing is not needed, may be add a little detail as covered in
the design doc?
##########
File path:
hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/CatalogReplicationSource.java
##########
@@ -0,0 +1,43 @@
+/*
+ * 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.replication.regionserver;
+
+import java.util.Collections;
+import org.apache.hadoop.hbase.wal.AbstractFSWALProvider;
+import org.apache.yetus.audience.InterfaceAudience;
+
+/**
+ * ReplicationSource that reads catalog WAL files -- e.g. hbase:meta WAL files
-- and lets through
+ * all WALEdits from these WALs. This ReplicationSource is NOT created via
+ * {@link ReplicationSourceFactory}.
+ */
[email protected]
+class CatalogReplicationSource extends ReplicationSource {
+ CatalogReplicationSource() {
+ // Filters in hbase:meta WAL files and allows all edits, including 'meta'
edits (these are
+ // filtered out in the 'super' class default implementation).
+ super(p -> AbstractFSWALProvider.isMetaFile(p), Collections.emptyList());
+ }
+
+ @Override
+ public void logPositionAndCleanOldLogs(WALEntryBatch entryBatch) {
+ // Noop. This implementation does not persist state to backing storage nor
does it keep its
+ // WALs in a general map up in ReplicationSourceManager so just skip
calling through to the
+ // default implemenentation.
Review comment:
nit: perhaps add why this is not needed?
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
##########
@@ -0,0 +1,301 @@
+/**
+ * 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.commons.lang3.builder.ToStringStyle;
+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;
+import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
+/**
+ * <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, ToStringStyle.SHORT_PREFIX_STYLE)
+ .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;
+ private final static int UNINITIALIZED_NUM_OF_REPLICAS = -1;
+
+ 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 = UNINITIALIZED_NUM_OF_REPLICAS;
+ // 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 == UNINITIALIZED_NUM_OF_REPLICAS) {
+ 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) {
+ Preconditions.checkArgument(locateType == RegionLocateType.BEFORE ||
+ locateType == RegionLocateType.CURRENT,
+ "Expected type BEFORE or CURRENT but got: %s", 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.
+ if (locateType == RegionLocateType.BEFORE) {
+ entry = isEmptyStopRow ? tableCache.lastEntry() :
tableCache.lowerEntry(row);
+ } else {
+ entry = tableCache.floorEntry(row);
+ }
+
+ // It is not in the stale cache, return a random replica id.
+ if (entry == null) {
+ return getRandomReplicaId();
+ }
+
+ // The entry here is a possible match for the location. Check if the entry
times out first as
+ // long comparing is faster than comparing byte arrays(in most cases). It
could remove
+ // stale entries faster. If the possible match entry does not time out, it
will check if
+ // the entry is a match for the row passed in and select the replica id
accordingly.
+ if ((EnvironmentEdgeManager.currentTime() -
entry.getValue().getTimestamp()) >=
+ STALE_CACHE_TIMEOUT_IN_MILLISECONDS) {
+ LOG.debug("Entry for table {} with startKey {}, {} times out",
tablename, entry.getKey(),
+ entry);
+ tableCache.remove(entry.getKey());
+ return getRandomReplicaId();
+ }
+
+ byte[] endKey = entry.getValue().getEndKey();
+
+ // The following logic is borrowed from AsyncNonMetaRegionLocator.
+ if (isEmptyStopRow(endKey)) {
+ LOG.debug("Lookup {} goes to primary region", row);
+ return RegionInfo.DEFAULT_REPLICA_ID;
+ }
+
+ if (locateType == RegionLocateType.BEFORE) {
+ if (!isEmptyStopRow && Bytes.compareTo(endKey, row) >= 0) {
+ LOG.debug("Lookup {} goes to primary meta", row);
+ return RegionInfo.DEFAULT_REPLICA_ID;
+ }
+ } else {
+ if (Bytes.compareTo(row, endKey) < 0) {
+ LOG.debug("Lookup {} goes to primary meta", row);
+ return RegionInfo.DEFAULT_REPLICA_ID;
+ }
+ }
+
+ // Not in stale cache, return a random replica id.
+ return getRandomReplicaId();
+ }
+
+ // This class implements the Stoppable interface as chores needs a Stopable
object, there is
+ // no-op on this Stoppable object currently.
+ @Override
+ public void stop(String why) {
+ isStopped = true;
+ }
+
+ @Override
+ public boolean isStopped() {
+ return isStopped;
+ }
+
+ private void cleanupReplicaReplicaStaleCache() {
+ long curTimeInMills = EnvironmentEdgeManager.currentTime();
+ for (ConcurrentNavigableMap<byte[], StaleLocationCacheEntry> tableCache :
staleCache.values()) {
+ Iterator<Map.Entry<byte[], StaleLocationCacheEntry>> it =
+ tableCache.entrySet().iterator();
+ while (it.hasNext()) {
+ Map.Entry<byte[], StaleLocationCacheEntry> entry = it.next();
+ if (curTimeInMills - entry.getValue().getTimestamp() >=
+ STALE_CACHE_TIMEOUT_IN_MILLISECONDS) {
+ LOG.debug("clean entry {}, {} from stale cache", entry.getKey(),
entry.getValue());
+ it.remove();
+ }
+ }
+ }
+ }
+
+ private int refreshCatalogReplicaCount() {
+ int newNumOfReplicas = this.getNumOfReplicas.getAsInt();
+ LOG.debug("Refreshed replica count {}", newNumOfReplicas);
+ if (newNumOfReplicas == 1) {
+ LOG.warn("Table {}'s region replica count is 1, maybe a misconfiguration
or failure to "
+ + "fetch the replica count", tableName);
+ }
+ int cachedNumOfReplicas = this.numOfReplicas;
+
+ // If the returned number of replicas is 1, it is mostly caused by failure
to fetch the
+ // replica count. Do not update the numOfReplicas in this case.
+ if ((cachedNumOfReplicas == UNINITIALIZED_NUM_OF_REPLICAS) ||
+ ((cachedNumOfReplicas != newNumOfReplicas) && (newNumOfReplicas != 1))) {
Review comment:
Perhaps return -1 for error case? If there is a legit use case that
reduces the replica count to 1 (now or in future), this logic is incorrect?
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaMode.java
##########
@@ -0,0 +1,64 @@
+/**
Review comment:
nit: /** usage is inconsistent across patches. Switch to /* everywhere?
##########
File path:
hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
##########
@@ -0,0 +1,301 @@
+/**
+ * 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.commons.lang3.builder.ToStringStyle;
+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;
+import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
+/**
+ * <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
Review comment:
nit: NotServingRegionException
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