huaxiangsun edited a comment on pull request #2645:
URL: https://github.com/apache/hbase/pull/2645#issuecomment-725527074
In ScannerCallableWithReplicas, there is more logic needed in Call(). This
is my patch in backport meta replica client.
{code}
`@@ -18,6 +18,8 @@
package org.apache.hadoop.hbase.client;
import static
org.apache.hadoop.hbase.client.RegionReplicaUtil.DEFAULT_REPLICA_ID;
import static
org.apache.hadoop.hbase.client.RegionReplicaUtil.isScanForSpecificReplicaRegion;
import
org.apache.hbase.thirdparty.com.google.common.annotations.VisibleForTesting;
import java.io.IOException;
@@ -45,10 +47,11 @@
/**
* This class has the logic for handling scanners for regions with and
without replicas.
* 1. A scan is attempted on the default (primary) region
* 2. The scanner sends all the RPCs to the default region until it is done,
or, there
* is a timeout on the default (a timeout of zero is disallowed).
* 3. If there is a timeout in (2) above, scanner(s) is opened on the
non-default replica(s)
* 1. A scan is attempted on the default (primary) region, or a specific
region.
* 2. The scanner sends all the RPCs to the default/specific region until it
is done, or, there
* is a timeout on the default/specific region (a timeout of zero is
disallowed).
* 3. If there is a timeout in (2) above, scanner(s) is opened on the
non-default replica(s) only
* for Consistency.TIMELINE without specific replica id specified.
* 4. The results from the first successful scanner are taken, and it is
stored which server
* returned the results.
* 5. The next RPCs are done on the above stored server until it is done or
there is a timeout,
@@ -160,7 +163,7 @@ public MoreResults moreResultsForScan() {
RegionLocations rl = null;
try {
rl = RpcRetryingCallerWithReadReplicas.getRegionLocations(true,
RegionReplicaUtil.DEFAULT_REPLICA_ID, cConnection, tableName,
DEFAULT_REPLICA_ID, cConnection, tableName,
currentScannerCallable.getRow());
} catch (RetriesExhaustedException | DoNotRetryIOException e) {
// We cannot get the primary replica region location, it is possible
that the region server
@@ -209,9 +212,10 @@ public MoreResults moreResultsForScan() {
LOG.debug("Scan with primary region returns " + e.getCause());
}
// If rl's size is 1 or scan's consitency is strong, it needs to throw
// out the exception from the primary replica
if ((regionReplication == 1) || (scan.getConsistency() ==
Consistency.STRONG)) {
// If rl's size is 1 or scan's consitency is strong, or scan is over
specific replica,
// it needs to throw out the exception from the primary replica
if ((regionReplication == 1) || (scan.getConsistency() ==
Consistency.STRONG) ||
isScanForSpecificReplicaRegion(scan)) {
// Rethrow the first exception
RpcRetryingCallerWithReadReplicas.throwEnrichedException(e, retries);
}
@@ -225,8 +229,9 @@ public MoreResults moreResultsForScan() {
// submit call for the all of the secondaries at once
int endIndex = regionReplication;
if (scan.getConsistency() == Consistency.STRONG) {
// When scan's consistency is strong, do not send to the secondaries
if ((scan.getConsistency() == Consistency.STRONG) ||
isScanForSpecificReplicaRegion(scan)){
// When scan's consistency is strong or scan is over specific replica
region,
// do not send to other replica regions.
endIndex = 1;
} else {
// TODO: this may be an overkill for large region replication
@@ -376,11 +381,13 @@ boolean isAnyRPCcancelled() {
this.callable = callable;
// For the Consistency.STRONG (default case), we reuse the caller
// to keep compatibility with what is done in the past
// For the Consistency.TIMELINE case, we can't reuse the caller
// For the Consistency.TIMELINE case, there are two cases. The first
case is that
// caller targets to a specific replica region, it can reuse the
caller.
// Otherwise, we can't reuse the caller
// since we could be making parallel RPCs (caller.callWithRetries is
synchronized
// and we can't invoke it multiple times at the same time)
this.caller = ScannerCallableWithReplicas.this.caller;
if (scan.getConsistency() == Consistency.TIMELINE) {
if (!isScanForSpecificReplicaRegion(scan)) {
this.caller =
RpcRetryingCallerFactory.instantiate(ScannerCallableWithReplicas.this.conf)
.<Result[]>newCaller();
}`
{code}
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