[LOG4J2-702] LoggerConfig#waitForCompletion is not thread safe

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 2.0-rc2
• Fix Version/s: 2.4
• Component/s: Core
• Assignee: Unassigned
• Reporter: Sean Bridges
• Created: 07/Jul/14 04:31
• Updated: 13/Oct/15 04:35
• Resolved: 13/Oct/15 04:35

Description

This is in trunk, svn commit 1608156

LoggerConfig#waitForCompletion uses an AtomicInteger counter to try to detect if there are any calls currently executing the log(Event) method, but it does not do so in a thread safe manner. Consider two threads A and B, where Thread A is calling clearAppenders(), and Thread B is calling log(Event),

Thread A  loggerConfig.clearAppenders()
Thread A  loggerConfig.waitForCompletion()
Thread A  counter.get() //returns 0
Thread A  //loggerConfig.waitForCompletion() returns

Thread B  loggerConfig.log(Event)
Thread B  counter.increment()

Thread A  proceeds assuming no log calls are onging, but thread B is in the log method

I'm not sure what the requirements are, but if the requirement is to not lose logging events, I think you need some sort of synchronization outside of the LoggerConfig object.

Issue Links

• relates to: LOG4J2-1121 LoggerConfig performance improvement: remove waitForCompletion and associated fields