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Amend HADOOP-8212 (Improve ActiveStandbyElector's behavior when session expires) 

Amendment patch incorporates following feedback from Bikas Saha:
- adds a new functional test for session expiration while in the standby state
- adds a safety check in the StatCallback for session expiration
- improves some comments


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-3042@1307128 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Todd Lipcon 2012-03-29 21:49:37 +00:00
parent a9471b97c1
commit 04416861eb
2 changed files with 51 additions and 1 deletions
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7
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ha/ActiveStandbyElector.java
View File

@ -470,13 +470,18 @@ public class ActiveStandbyElector implements StatCallback, StringCallback {
}
errorMessage = errorMessage
+ ". Not retrying further znode monitoring connection errors.";
} else if (isSessionExpired(code)) {
// This isn't fatal - the client Watcher will re-join the election
LOG.warn("Lock monitoring failed because session was lost");
return;
}
fatalError(errorMessage);
}
/**
* interface implementation of Zookeeper watch events (connection and node)
* interface implementation of Zookeeper watch events (connection and node),
* proxied by {@link WatcherWithClientRef}.
*/
synchronized void processWatchEvent(ZooKeeper zk, WatchedEvent event) {
Event.EventType eventType = event.getType();

45
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ha/TestActiveStandbyElectorRealZK.java
View File

@ -26,6 +26,7 @@ import java.util.UUID;
import org.apache.commons.logging.impl.Log4JLogger;
import org.apache.hadoop.ha.ActiveStandbyElector.ActiveStandbyElectorCallback;
import org.apache.hadoop.ha.ActiveStandbyElector.State;
import org.apache.log4j.Level;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.server.ZooKeeperServer;
@ -196,4 +197,48 @@ public class TestActiveStandbyElectorRealZK extends ClientBase {
checkFatalsAndReset();
}
@Test(timeout=15000)
public void testHandleSessionExpirationOfStandby() throws Exception {
// Let elector 0 be active
electors[0].ensureParentZNode();
electors[0].joinElection(appDatas[0]);
ZooKeeperServer zks = getServer(serverFactory);
ActiveStandbyElectorTestUtil.waitForActiveLockData(null,
zks, PARENT_DIR, appDatas[0]);
Mockito.verify(cbs[0], Mockito.timeout(1000)).becomeActive();
checkFatalsAndReset();
// Let elector 1 be standby
electors[1].joinElection(appDatas[1]);
ActiveStandbyElectorTestUtil.waitForElectorState(null, electors[1],
State.STANDBY);
LOG.info("========================== Expiring standby's session");
zks.closeSession(electors[1].getZKSessionIdForTests());
// Should enter neutral mode when disconnected
Mockito.verify(cbs[1], Mockito.timeout(1000)).enterNeutralMode();
// Should re-join the election and go back to STANDBY
ActiveStandbyElectorTestUtil.waitForElectorState(null, electors[1],
State.STANDBY);
checkFatalsAndReset();
LOG.info("========================== Quitting election");
electors[1].quitElection(false);
// Double check that we don't accidentally re-join the election
// by quitting elector 0 and ensuring elector 1 doesn't become active
electors[0].quitElection(false);
// due to receiving the "expired" event.
Thread.sleep(1000);
Mockito.verify(cbs[1], Mockito.never()).becomeActive();
ActiveStandbyElectorTestUtil.waitForActiveLockData(null,
zks, PARENT_DIR, null);
checkFatalsAndReset();
}
}