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From "Jingguo Yao (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-7055) Update of commons logging libraries causes EventCounter to count logging events incorrectly
Date Sun, 27 Mar 2011 04:43:05 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-7055?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13011724#comment-13011724
] 

Jingguo Yao commented on HADOOP-7055:
-------------------------------------

When EventCounter appender is triggered, it only updates its counts field. So equals overhead
is not negligible compared to the actual logging which is counts field updating in this case.

But if we think that the overhead incurred by equals is negligible on the overall performance,
we can use equals.

> Update of commons logging libraries causes EventCounter to count logging events incorrectly
> -------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-7055
>                 URL: https://issues.apache.org/jira/browse/HADOOP-7055
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: metrics
>    Affects Versions: 0.21.0, 0.21.1, 0.22.0, 0.23.0
>            Reporter: Jingguo Yao
>            Assignee: Jingguo Yao
>   Original Estimate: 0.5h
>  Remaining Estimate: 0.5h
>
> Hadoop 0.20.2 uses commons logging 1.0.4. EventCounter works correctly with this version
of commons logging. Hadoop 0.21.0 uses commons logging 1.1.1 which causes EventCounter to
count logging events incorrectly. I have verified it with Hadoop 0.21.0. After start-up of
hadoop, I checked jvmmetrics.log after several minutes. In every metrics record, "logError=0,
logFatal=0, logInfo=3, logWarn=0" was shown. The following text is an example.
> jvm.metrics: hostName=jingguolin, processName=DataNode, sessionId=, gcCount=3, gcTimeMillis=31,
logError=0, logFatal=0, logInfo=3, logWarn=0, maxMemoryM=888.9375, memHeapCommittedM=38.0625,
memHeapUsedM=3.6539612, memNonHeapCommittedM=18.25, memNonHeapUsedM=11.335686, threadsBlocked=0,
threadsNew=0, threadsRunnable=8, threadsTerminated=0, threadsTimedWaiting=6, threadsWaiting=6
> Then I stopped hadoop and replaced commons logging 1.1.1 with 1.0.4. After the re-start
of hadoop, a lot of logging events showed up in jvmmetrics.log.
> I have checked the source code of Log4JLogger for both 1.0.4 (http://svn.apache.org/viewvc/commons/proper/logging/tags/LOGGING_1_0_4/src/java/org/apache/commons/logging/impl/Log4JLogger.java?view=markup)
and 1.1.1 (http://svn.apache.org/viewvc/commons/proper/logging/tags/commons-logging-1.1.1/src/java/org/apache/commons/logging/impl/Log4JLogger.java?view=markup).
For 1.0.4, Level instances such as Level.INFO are used to construct LoggingEvent. But for
1.1.1, Priority instances such as Priority.INFO are used to construct LoggingEvent. So 1.1.1
version's event.getLevel() always returns Priority instances. EventCounter append method's
"==" check always fails between a Level instance and a Priority instance. For "logInfo=3"
metrics records produced by commons logging 1.1.1., I think that these 3 logging events are
produced by log4j code directly instead of through commons logging API. The following code
is EventCounter's append method.
>     public void append(LoggingEvent event) {
>         Level level = event.getLevel();
>         if (level == Level.INFO) {
>             counts.incr(INFO);
>         }
>         else if (level == Level.WARN) {
>             counts.incr(WARN);
>         }
>         else if (level == Level.ERROR) {
>             counts.incr(ERROR);
>         }
>         else if (level == Level.FATAL) {
>             counts.incr(FATAL);
>         }
>     }

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