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https://issues.apache.org/jira/browse/LOG4J2-3447?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Piotr Karwasz resolved LOG4J2-3447.
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Resolution: Fixed
[~PoojaTheCoder],
Can you check the latest {{2.17.3-SNAPSHOT}} snapshot and close the issue if it
fixes your problem?
> Log4j 1.x 2.17.2 bridge - Synchronization issue in multithreading (Losing
> huge data in multithreading)
> ------------------------------------------------------------------------------------------------------
>
> Key: LOG4J2-3447
> URL: https://issues.apache.org/jira/browse/LOG4J2-3447
> Project: Log4j 2
> Issue Type: Bug
> Components: Log4j 1.2 bridge
> Affects Versions: 2.17.2
> Reporter: Pooja Pandey
> Assignee: Piotr Karwasz
> Priority: Major
> Fix For: 2.17.3
>
> Attachments: JavaLoggingMultiThTest.txt
>
>
> In our application we have migrated from log4j1.x to log4j1.x 2.17.2 bridge.
> With Log4j1.x there was no issue with multithreading but with log4j 1.x
> bridge we have noticed that in multithreading environment there is a huge
> data loss while logging, however single thread works fine. I see that in
> Category.java which Logger extends; many methods are not synchronized any
> more in log4j1.x bridge however which were synchronized in case of log4j1.x.
> I suspect this could be root causes of this multithreading problem.
> So as per my understanding synchronized class Category.java in the log4j1.x
> has become unsynchronized in log4j1.x 2.17.2 bridge. I am not sure if I am
> missing something.
> We wanted to know how to achieve successful multithreading logging using
> log4j 1.x 2.17.2 bridge.
> For reference, few methods which were synchronized earlier in log4j1.x but
> not anymore in log4j1.x bridge.
> # public void addAppender(final Appender appender)
> # public Appender getAppender(final String name)
> # public void removeAppender(final Appender appender)
> # public void removeAllAppenders()
> # In log4j 1.x bridge following method is used for logging which doesn't
> look like synchronized. -> void maybeLog(final String fqcn, final
> org.apache.logging.log4j.Level level, final Object message, final Throwable
> throwable); However in log4j1.x following method was used which looks like
> synchronized. -> void forcedLog(String fqcn, Priority level, Object message,
> Throwable t) -> void callAppenders(LoggingEvent event), where method void
> callAppenders(LoggingEvent event) looks snychronized.
>
> I am attaching sample test program as well which I have used to test
> multithreading logging in my application. (Please Note that in this test
> program, class CustomLogger is a dummy class, which you would need to replace
> with your logger). We are using Custom Rolling Appender in our application
> and following is the content of log4j properties file.
> [^JavaLoggingMultiThTest.txt]
> #Custom Rolling Appender
> log4j.appender.R=test.CustomMultiProcessRollingAppender
> log4j.appender.R.File=${user.home}/log4j-multithreading-test.log
> log4j.appender.R.RollOverOnStartup=true
> log4j.appender.R.RollOverOnSize=false
> log4j.appender.R.RollOverMaxFileSize=100MB
> log4j.appender.R.RollOverMaxBackupIndex=10
> log4j.appender.R.RollOverOnPeriodic=false
> log4j.appender.R.RollOverPeriodicStartDate=
> log4j.appender.R.RollOverPeriodicFrequency=1
> log4j.appender.R.layout=org.apache.log4j.PatternLayout
> log4j.appender.R.layout.ConversionPattern=%d %-8M [%t] - %m%n
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