[Log4cplus-devel] [log4cplus:bugs] #333 AsyncAppender leads to loss logs, when server terminated normally.

[Václav H. <wi...@us...>]

- **status**: open --> closed
- **Comment**:

I think this is now fully fixed.



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** [bugs:#333] AsyncAppender leads to loss logs, when server terminated normally.**

**Status:** closed
**Group:** v1.2.0
**Labels:** v1.2.0 Appender 
**Created:** Fri Aug 19, 2016 01:43 AM UTC by Justin Sage
**Last Updated:** Sun Aug 21, 2016 12:51 PM UTC
**Owner:** Václav Haisman


A bug in Asynchronous Log:
We are using AsyncAppender to record our log on CentOS-6.3, and we found a fatal bug. when our server terminated normally, we lost a lot of log. It's because that when AsyncAppender call its close function, it doesn't call the other Appenders' close function. As a result, their file stream isn't close explicitly and a lot of logs aren't flushed to disk.

Our log configure is as follow:

~~~{.properties}
log4cplus.logger.global = INFO, AA
log4cplus.appender.AA=log4cplus::AsyncAppender
log4cplus.appender.AA.QueueLimit=10000
log4cplus.appender.AA.Appender=log4cplus::DailyRollingFileAppender
log4cplus.appender.AA.Appender.Schedule=HOURLY
log4cplus.appender.AA.Appender.Threshold = INFO
log4cplus.appender.AA.Appender.DatePattern=%Y-%m-%d-%H
log4cplus.appender.AA.Appender.File=./logger_test.log
log4cplus.appender.AA.Appender.ImmediateFlush=false
log4cplus.appender.AA.Appender.MaxFileSize=1000MB  
log4cplus.appender.AA.Appender.MaxBackupIndex=100
log4cplus.appender.AA.Appender.Append=true
log4cplus.appender.AA.Appender.layout=log4cplus::PatternLayout  
log4cplus.appender.AA.Appender.layout.ConversionPattern=%D{%Y-%m-%d %H:%M:%S,%Q} [%t] %-5p %m%n
~~~

We tried to set `log4cplus.appender.AA.Appender.ImmediateFlush=true`, and it works. But it's bad for I/O performence of system.

We have a better solution, and it works well. Just call `removeAllAppenders()` function at the end of `AsyncAppender::close()`. It will ensure all logs are flushed to the disk when server terminates.

~~~{.cpp}
void
AsyncAppender::close ()
{
    unsigned ret = queue->signal_exit ();
    if (ret & (thread::Queue::ERROR_BIT | thread::Queue::ERROR_AFTER))
        getErrorHandler ()->error (
            LOG4CPLUS_TEXT ("Error in AsyncAppender::close"));
    queue_thread->join ();
    
    removeAllAppenders();
}
~~~



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