[
https://issues.apache.org/jira/browse/HADOOP-9916?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Luke Lu updated HADOOP-9916:
----------------------------
Resolution: Fixed
Fix Version/s: 2.1.1-beta
Hadoop Flags: Reviewed
Status: Resolved (was: Patch Available)
Committed to trunk, branch-2, 2.1-beta. Thanks Binglin for the patch!
> Race condition in ipc.Client causes TestIPC timeout
> ---------------------------------------------------
>
> Key: HADOOP-9916
> URL: https://issues.apache.org/jira/browse/HADOOP-9916
> Project: Hadoop Common
> Issue Type: Bug
> Reporter: Binglin Chang
> Assignee: Binglin Chang
> Priority: Minor
> Fix For: 2.1.1-beta
>
> Attachments: HADOOP-9916.v1.patch
>
>
> TestIPC timeouts occasionally, for example:
> [https://issues.apache.org/jira/browse/HDFS-5130?focusedCommentId=13749870&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13749870]
> [https://issues.apache.org/jira/browse/HADOOP-9915?focusedCommentId=13753302&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13753302]
> Look into the code, there is race condition in oah.ipc.Client, the race
> condition happen between RPC call thread and connection read response thread:
> {code}
> if (status == RpcStatusProto.SUCCESS) {
> Writable value = ReflectionUtils.newInstance(valueClass, conf);
> value.readFields(in); // read value
> call.setRpcResponse(value);
> calls.remove(callId);
> {code}
> Read Thread:
> Connection.receiveRpcResponse-> call.setRpcResponse(value) -> notify Call
> Thread
> Call Thread:
> Client.call -> Connection.addCall(retry with the same callId) -> notify read
> thread
> Read Thread:
> calls.remove(callId) # intend to remove old call, but removes newly added
> call...
> Connection.waitForWork end up wait maxIdleTime and close the connection. The
> call never get response and dead.
> The problem doesn't show because previously callId is unique, we never
> accidentally remove newly added calls, but when retry added this race
> condition became possible.
> To solve this, we can simply change order, remove the call first, then notify
> call thread.
> Note there are many places need this order change(normal case, error case,
> cleanup case)
> And there are some minor issues in TestIPC:
> 1. there are two method with same name:
> void testSerial()
> void testSerial(int handlerCount, boolean handlerSleep, ...)
> the second is not a test case(so should not use testXXX prefix), but
> somehow it causes testSerial(first one) run two times, see test report:
> {code}
> <testcase time="26.896" classname="org.apache.hadoop.ipc.TestIPC"
> name="testSerial"/>
> <testcase time="25.426" classname="org.apache.hadoop.ipc.TestIPC"
> name="testSerial"/>
> {code}
> 2. timeout annotation should be added, so next time related log is available.
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