How to clear asynchronous loggers in Log4J2 (with break)
I am using Log4J2 "Generate all logs asynchronous" by setting:
-DLog4jContextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector.
https://logging.apache.org/log4j/2.x/manual/async.html
I am processing a lot of logs and then stopping them before exiting:
org.apache.logging.log4j.core.Logger coreLogger = (org.apache.logging.log4j.core.Logger) logger;
org.apache.logging.log4j.core.LoggerContext context = (org.apache.logging.log4j.core.LoggerContext) coreLogger.getContext();
Map<String, Appender> appenders = context.getConfiguration().getAppenders();
for (Appender appender : appenders.values()) {
appender.stop();
}
By doing this, I hope it cleans up the asynchronous applications and writes the remaining logs to disk before exiting the program.
But here's what happens:
2015-05-19 14:09:58,540 ERROR Attempted to append to non-started appender myFileAppender
Exception in thread "AsyncLogger-1" java.lang.RuntimeException: org.apache.logging.log4j.core.appender.AppenderLoggingException: Attempted to append to non-started appender myFileAppender
at com.lmax.disruptor.FatalExceptionHandler.handleEventException(FatalExceptionHandler.java:45)
at com.lmax.disruptor.BatchEventProcessor.run(BatchEventProcessor.java:147)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.logging.log4j.core.appender.AppenderLoggingException: Attempted to append to non-started appender myFileAppender
at org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:89)
at org.apache.logging.log4j.core.config.LoggerConfig.callAppenders(LoggerConfig.java:430)
at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:409)
at org.apache.logging.log4j.core.Logger$PrivateConfig.logEvent(Logger.java:288)
at org.apache.logging.log4j.core.async.AsyncLogger.actualAsyncLog(AsyncLogger.java:305)
at org.apache.logging.log4j.core.async.RingBufferLogEvent.execute(RingBufferLogEvent.java:100)
at org.apache.logging.log4j.core.async.RingBufferLogEventHandler.onEvent(RingBufferLogEventHandler.java:43)
at org.apache.logging.log4j.core.async.RingBufferLogEventHandler.onEvent(RingBufferLogEventHandler.java:28)
at com.lmax.disruptor.BatchEventProcessor.run(BatchEventProcessor.java:128)
... 3 more
So the shutdown doesn't seem like it really flushes and the logger fails.
My conf:
<Configuration>
<Appenders>
<RollingFile name="myFileAppender" fileName="/tmp/test.log" ignoreExceptions="false" immediateFlush="false">
<PatternLayout><Pattern>%m%n</Pattern></PatternLayout>
<Policies>
<TimeBasedTriggeringPolicy />
</Policies>
</RollingFile>
<Console name="STDOUT">
<PatternLayout pattern="%C{1.} %m %level MDC%X%n"/>
</Console>
</Appenders>
<Loggers>
<Logger name="myLogger" level="info" additivity="false">
<AppenderRef ref="myFileAppender" />
</Logger>
<Root level="fatal">
<AppenderRef ref="STDOUT"/>
</Root>
</Loggers>
</Configuration>
How can I reset / sync log4j2?
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Log4j2 has a disconnect hook (for non-web applications) that takes care of the background thread to handle any events still in the queue. Therefore, it is best not to stop applications when they are still in use. Let log4j2 take care of the cleanup.
To stop the async log completely, you can call org.apache.logging.log4j.core.async.AsyncLogger.stop()
. This is blocked until all messages have been cleared. Remember:
- This only works if the "Creating all logins induction" setting:
-DLog4jContextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector
. - Are you sure you want to measure this? Disk I / O will dominate your measurements. If you want to enable I / O, it is easier to disable asynchronous logging and measure synchronous logging (including I / O). Most people are interested in the effect of registration on their application, so they only measure the duration of the logger calls and do not include the background thread in their measurements.
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