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https://issues.apache.org/jira/browse/LOG4J2-3274?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17463902#comment-17463902
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Ralph Goers edited comment on LOG4J2-3274 at 12/22/21, 3:45 PM:
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You will have to show more of the stack trace than that. It is perfectly normal
for a thread to be blocked in writeBytes. It simply means some other thread is
writing to the file. Can you supply the full thread dump?
Also, line 156 in RollingFileAppender was changed from
{code:java}
isImmediateFlush()
{code}
to
{code:java}
!isBufferedIo || isImmediateFlush() {code}
which is correct. Are you looking somewhere else?
was (Author: [email protected]):
You will have to show more of the stack trace than that. It is perfectly normal
for a thread to be blocked in writeBytes. It simply means some other thread is
writing to the file. Can you supply the full thread dump?
Also, the line was changed from
{code:java}
isImmediateFlush()
{code}
to
{code:java}
!isBufferedIo || isImmediateFlush() {code}
which is correct.
> Log4j2 deadlock version 2.16
> ----------------------------
>
> Key: LOG4J2-3274
> URL: https://issues.apache.org/jira/browse/LOG4J2-3274
> Project: Log4j 2
> Issue Type: Bug
> Reporter: Faisal Khan Thayub Khan
> Priority: Major
>
> My application is a sprint boot application that uses log4j2 and runs in a
> Wildfly server. After the zero day attack, we upgraded to the latest log4j2
> version(2.16). But after the log4j upgrade, my application stops working once
> in a while. And when I looked at the threaddumps, I found that there is a
> deadlock created by log4j.
> When analysing this issue, I came through a possible defect in log4j code.
> Not sure if that can result in a deadlock.
> *Log4J possible bug* - As per the release notes, there was a fix to {*}Enable
> immediate flush on RollingFileAppender when buffered i/o is not enabled.
> (LOG4J2-3114){*}. But the code just does the opposite in
> {*}RollingFileAppenderBuilder{*}.
> It should have been {{{}if(!bufferedIo) \{ immediateFlush = true; }{{}}}}.
> And one of my appender explicitly sets bufferedIo value to true. I know that
> log4j does a bufferedio by default and it is not necessary to set this flag
> explicitly. But unfortunately the code that I am working on is a legacy code
> and the configuration was working fine before the upgrade.
> {{I have added my log4j configuration in here
> [https://stackoverflow.com/questions/70450611/log4j2-deadlock]}}
>
> *Extract from Thread dump:*
> "default task-128" #450 prio=5 os_prio=0 tid=0x00007f31f80cf800 nid=0x14c8
> waiting for monitor entry [0x00007f31a7d88000]
> java.lang.Thread.State: BLOCKED (on object monitor)
> at
> org.apache.logging.log4j.core.appender.OutputStreamManager.writeBytes(OutputStreamManager.java:352)
> - waiting to lock <0x00000000c0e70eb0> (a
> org.apache.logging.log4j.core.appender.OutputStreamManager)
> at
> org.apache.logging.log4j.core.layout.TextEncoderHelper.writeEncodedText(TextEncoderHelper.java:96)
> at
> org.apache.logging.log4j.core.layout.TextEncoderHelper.encodeText(TextEncoderHelper.java:65)
> at
> org.apache.logging.log4j.core.layout.StringBuilderEncoder.encode(StringBuilderEncoder.java:68)
> at
> org.apache.logging.log4j.core.layout.StringBuilderEncoder.encode(StringBuilderEncoder.java:32)
> at
> org.apache.logging.log4j.core.layout.PatternLayout.encode(PatternLayout.java:228)
> at
> org.apache.logging.log4j.core.layout.PatternLayout.encode(PatternLayout.java:60)
> at
> org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.directEncodeEvent(AbstractOutputStreamAppender.java:197)
> at
> org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.tryAppend(AbstractOutputStreamAppender.java:190)
> at
> org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.append(AbstractOutputStreamAppender.java:181)
> at
> org.apache.logging.log4j.core.config.AppenderControl.tryCallAppender(AppenderControl.java:161)
> at
> org.apache.logging.log4j.core.config.AppenderControl.callAppender0(AppenderControl.java:134)
> at
> org.apache.logging.log4j.core.config.AppenderControl.callAppenderPreventRecursion(AppenderControl.java:125)
> at
> org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:89)
> at
> org.apache.logging.log4j.core.config.LoggerConfig.callAppenders(LoggerConfig.java:542)
> at
> org.apache.logging.log4j.core.config.LoggerConfig.processLogEvent(LoggerConfig.java:500)
> at
> org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:483)
> at
> org.apache.logging.log4j.core.config.LoggerConfig.logParent(LoggerConfig.java:533)
> at
> org.apache.logging.log4j.core.config.LoggerConfig.processLogEvent(LoggerConfig.java:502)
> at
> org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:483)
> at
> org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:388)
> at
> org.apache.logging.log4j.core.config.AwaitCompletionReliabilityStrategy.log(AwaitCompletionReliabilityStrategy.java:63)
> at org.apache.logging.log4j.core.Logger.logMessage(Logger.java:153)
> at org.apache.logging.slf4j.Log4jLogger.log(Log4jLogger.java:376)
> at
> org.apache.commons.logging.impl.SLF4JLocationAwareLog.error(SLF4JLocationAwareLog.java:203)
> at
> org.springframework.boot.web.support.ErrorPageFilter.handleCommittedResponse(ErrorPageFilter.java:225)
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