[LOG4NET-510] FileAppender.InterProcessLock.AcquireLock blocks everything

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 1.2.13
• Component/s: Appenders
• Environment: Windows 2012
• Flags: Important
• Assignee: Unassigned
• Reporter: StevenXi
• Created: 14/Apr/16 08:23
• Updated: 14/Sep/20 06:41
• Resolved: 14/Sep/20 06:41

Description

There's a chance InterProcessLock.AcquireLock hangs, and lots of Appender.AppenderSkeleton.DoAppend threads queued.

It happens to our service every 2 days, all happen after mid-night. So after a new log file created, few new line in the file added. But not always happens.

As there're hundreds of Appender.AppenderSkeleton.DoAppend threads queued, it blocks everywhere in the service that uses log4net.

log4net is supposed to be 'failure-free' or at least fails quietly, not block the whole application.

config uses
<lockingModel type="log4net.Appender.FileAppender+InterProcessLock" />

So far it has hanged for few (8+) hours already.

The attached screen shot was taken by remote debug from a server after 8+ hours of hanging.

Issue Links

• is related to: LOG4NET-367 RollingFileAppender-NG: rewrite the RollingFileAppender
• relates to: LOG4NET-252 RollingFileAppender stops logging intermittently when it tries to roll over the log file
• relates to: LOG4NET-552 Add new locking model to the FileAppender that works fine when multiple processes log and roll the same file