Allan Yang created HBASE-16238:
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Summary: It's useless to catch SESSIONEXPIRED exception and retry
in RecoverableZooKeeper
Key: HBASE-16238
URL: https://issues.apache.org/jira/browse/HBASE-16238
Project: HBase
Issue Type: Bug
Components: Zookeeper
Reporter: Allan Yang
Priority: Minor
After HBASE-5549, SESSIONEXPIRED exception was caught and retried with other
zookeeper exceptions like ConnectionLoss. But it is useless to retry when a
session expired happens, since the retry will never be successful. Though there
is a config called "zookeeper.recovery.retry" to control retry times, in our
cases, we set this config to a very big number like "99999". When a session
expired happens, the regionserver should kill itself, but because of the
retrying, threads of regionserver stuck at trying to reconnect to zookeeper,
and never properly shut down.
{code}
public Stat exists(String path, boolean watch)
throws KeeperException, InterruptedException {
TraceScope traceScope = null;
try {
traceScope = Trace.startSpan("RecoverableZookeeper.exists");
RetryCounter retryCounter = retryCounterFactory.create();
while (true) {
try {
return checkZk().exists(path, watch);
} catch (KeeperException e) {
switch (e.code()) {
case CONNECTIONLOSS:
case SESSIONEXPIRED: //we shouldn't catch this
case OPERATIONTIMEOUT:
retryOrThrow(retryCounter, e, "exists");
break;
default:
throw e;
}
}
retryCounter.sleepUntilNextRetry();
}
} finally {
if (traceScope != null) traceScope.close();
}
}
{code}
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