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Date: Fri, 27 Jun 2008 08:00:45 -0700 (PDT)
From: "Steve Loughran (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Created: (HADOOP-3654) Log4J logging of stack trace may
 deadlock JRockit in TestFileSystem
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Log4J logging of stack trace may deadlock JRockit in TestFileSystem
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                 Key: HADOOP-3654
                 URL: https://issues.apache.org/jira/browse/HADOOP-3654
             Project: Hadoop Core
          Issue Type: Bug
          Components: conf
    Affects Versions: 0.19.0
         Environment: Ubuntu 8.04 x86_64 4-way running java version "1.6.0_02"
Java(TM) SE Runtime Environment (build 1.6.0_02-b05)
BEA JRockit(R) (build R27.4.0-90-89592-1.6.0_02-20070928-1715-linux-x86_64, compiled mode)

Linux 2.6.22-15-generic #1 SMP Tue Jun 10 08:52:15 UTC 2008 x86_64 GNU/Linux

            Reporter: Steve Loughran
            Priority: Minor


This is being added as a bugrep so that other people can find it, and the workaround

1. On my machine TestFileSystem will hang, even overnight -even though the build was set with a timeout. 
2. halting the build left a JVM running; it was not being killed.
3. Under the IDE, the main thread appears hung in the native library call to get a stack trace, somewhere inside Log4J
4. the IDE could not halt the build, and could not be shut down cleanly either

The fix for this problem was to edit conf/log4j.properties and switch to a log4J log pattern that did not print the line of the code

log4j.appender.console.layout.ConversionPattern=%-4r %-5p %c %x - %m%n

Given that working out a stack trace can be an expensive call, and that it can apparently hang some JVMs, perhaps it should not be the default.

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