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From "Pavel Kuznetsov (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (IGNITE-9447) Benchmarks hangs intemittently due to distributed race condition.
Date Fri, 05 Oct 2018 10:57:00 GMT

    [ https://issues.apache.org/jira/browse/IGNITE-9447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16639657#comment-16639657
] 

Pavel Kuznetsov commented on IGNITE-9447:
-----------------------------------------

[~vozerov] Could you please take a look at the patch?

> Benchmarks hangs intemittently due to distributed race condition.
> -----------------------------------------------------------------
>
>                 Key: IGNITE-9447
>                 URL: https://issues.apache.org/jira/browse/IGNITE-9447
>             Project: Ignite
>          Issue Type: Bug
>          Components: sql
>            Reporter: Pavel Kuznetsov
>            Assignee: Pavel Kuznetsov
>            Priority: Minor
>
> If we run more than one yardstick driver, benchmark hangs intermittently.
> We've got yardstick's base driver class org.apache.ignite.yardstick.IgniteAbstractBenchmark
it has logic to wait all the nodes in the cluster.
> {noformat}
> final CountDownLatch nodesStartedLatch = new CountDownLatch(1);
>         ignite().events().localListen(new IgnitePredicate<Event>() {
>             @Override public boolean apply(Event gridEvt) {
>                 if (nodesStarted())
>                     nodesStartedLatch.countDown();
>                 return true;
>             }
>         }, EVT_NODE_JOINED);
>         if (!nodesStarted()) {
>             println(cfg, "Waiting for " + (args.nodes() - 1) + " nodes to start...");
>             nodesStartedLatch.await();
>         }
> {noformat}
> This code is executed on every driver node.
> If we want to close local ignite instance just after cluster is ready (containing expected
number of nodes), sometimes we'll have dead lock:
> 1) cluster contains N-1 nodes, all nodes are waiting for the Nth node.
> 2) Nth node is connected, cluster receives message, waitForNodes code of Nth node is
not executed.
> 3) N-1 nodes got this message and stop waiting.
> 4) N-1 thinks that cluster is ready and call ignite.close() on their local instances
> 5) Nth node starts waiting for cluster to contain number of nodes, but N-1 of them closed
their instances
> 6) Nth node is waiting infinitely. 
> We can avoid this problem if we use distributed CountDownLatch



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