Daniel Widdis created LOG4J2-880:
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Summary: 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"}}
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)
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