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https://issues.apache.org/jira/browse/HDFS-14196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16742368#comment-16742368
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Surendra Singh Lilhore commented on HDFS-14196:
-----------------------------------------------
Thanks [[email protected]].
{{bufferCount}} increment only in insert() method and immediately check the
{{bufferCount}}. If it reached to buffer max size(500) then it will be changed
to 0. {{ArrayIndexOutOfBoundsException}} came for 500 index. So it is not
possible two thread can change the value.
{code:java}
synchronized public void insert(long v) {
buffer[bufferCount] = v;
bufferCount++;
count++;
if (bufferCount == buffer.length) {
insertBatch();
compress();
}
}{code}
I though may be because of thread caching same value is not visible for all the
thread for {{bufferCount}}. {{volatile}} can solve this problem.
Correct me if I am wrong :)
> ArrayIndexOutOfBoundsException in JN metrics makes JN out of sync
> -----------------------------------------------------------------
>
> Key: HDFS-14196
> URL: https://issues.apache.org/jira/browse/HDFS-14196
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Ranith Sardar
> Assignee: Ranith Sardar
> Priority: Major
> Attachments: HDFS-14196.001.patch
>
>
> {{2018-11-26 21:55:39,100 | WARN | IPC Server handler 4 on 25012 | IPC Server
> handler 4 on 25012, call
> org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocol.journal from
> 192.100.2.4:41622 Call#785140293 Retry#0 | Server.java:2334
> java.lang.ArrayIndexOutOfBoundsException: 500 at
> org.apache.hadoop.metrics2.util.SampleQuantiles.insert(SampleQuantiles.java:114)
> at
> org.apache.hadoop.metrics2.lib.MutableQuantiles.add(MutableQuantiles.java:130)
> at
> org.apache.hadoop.hdfs.qjournal.server.JournalMetrics.addSync(JournalMetrics.java:120)
> at org.apache.hadoop.hdfs.qjournal.server.Journal.journal(Journal.java:400)
> at
> org.apache.hadoop.hdfs.qjournal.server.JournalNodeRpcServer.journal(JournalNodeRpcServer.java:153)
> at
> org.apache.hadoop.hdfs.qjournal.protocolPB.QJournalProtocolServerSideTranslatorPB.journal(QJournalProtocolServerSideTranslatorPB.java:158)
> at
> org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos$QJournalProtocolService$2.callBlockingMethod(QJournalProtocolProtos.java:2542}}
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