[
https://issues.apache.org/jira/browse/LOG4J2-880?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14183907#comment-14183907
]
Daniel Widdis commented on LOG4J2-880:
--------------------------------------
Thanks for commenting, Laurent. After knocking my head against this for a few
days I've come to similar conclusions that this is not really a bug, but an
(unwanted) feature of using the non-redirected System.out. More to the point,
there's not really any reliable condition that one can test to figure out if
the BufferedOutputStream is blocked, so even if it were a bug, it's not really
fixable.
I am in agreement that the default behavior of the appender should be changed
to 'follow="true"' but I'll leave it to wiser, more experienced developers to
make that call.
> ConsoleAppender hangs when writing to System.out in a spawned JVM
> -----------------------------------------------------------------
>
> Key: LOG4J2-880
> URL: https://issues.apache.org/jira/browse/LOG4J2-880
> Project: Log4j 2
> Issue Type: Bug
> Affects Versions: 2.0.2
> Reporter: Daniel Widdis
>
> I am using Log4J2 in an application using Java Parallel Processing Framework
> (www.jppf.org). One of the features of JPPF is node provisioning, in which a
> node process can spawn additional JVMs. However, since the spawned JVMs do
> not have a "console" the only way to access System.out is by redirecting it
> to a file, which is done automatically.
> By default, the ConsoleAppender sets {{follow="false"}}. However, rather
> than exiting gracefully doing nothing, it locks an OutputStreamManger and
> never releases it. This causes the application to hang.
> The problem is easily worked around by setting {{follow="true"}} on the
> appender. However, I propose that the default behavior for {{follow="false"}}
> when System.out is unavailable (as in a spawned JVM) should simply return
> without doing anything, rather than locking resources.
> Relevant stack trace of the thread holding the lock is shown below. The
> {{writeBytes()}} method never returned. Other threads attempted to write but
> were blocked because of this lock.
> "pool-5-thread-6" prio=6 tid=0x000000000c0c2000 nid=0x2ce4 runnable
> [0x000000000d9ae000]
> java.lang.Thread.State: RUNNABLE
> at java.io.FileOutputStream.writeBytes(Native Method)
> at java.io.FileOutputStream.write(Unknown Source)
> at java.io.BufferedOutputStream.write(Unknown Source)
> - locked <0x00000000d0063960> (a java.io.BufferedOutputStream)
> at java.io.PrintStream.write(Unknown Source)
> - locked <0x00000000d0063940> (a java.io.PrintStream)
> at
> org.apache.logging.log4j.core.appender.OutputStreamManager.write(OutputStreamManager.java:122)
> - locked <0x00000000d00638e0> (a
> org.apache.logging.log4j.core.appender.OutputStreamManager)
> at
> org.apache.logging.log4j.core.appender.OutputStreamManager.write(OutputStreamManager.java:136)
> at
> org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.append(AbstractOutputStreamAppender.java:106)
> at
> org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:97)
> at
> org.apache.logging.log4j.core.config.LoggerConfig.callAppenders(LoggerConfig.java:428)
> at
> org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:407)
> at
> org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:410)
> at
> org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:365)
> at org.apache.logging.log4j.core.Logger.logMessage(Logger.java:112)
> at
> org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:1336)
> at
> org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:1325)
> at
> org.apache.logging.log4j.spi.AbstractLogger.warn(AbstractLogger.java:1738)
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
