[LOG4J2-1172] ThreadLocal leak [AsyncLogger$Info] on Tomcat when using AsyncLoggerContextSelector

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4, 2.4.1, 2.5
• Fix Version/s: 2.5
• Component/s: Configurators, Web/Servlet
• Assignee: Remko Popma
• Reporter: Remko Popma
• Created: 23/Oct/15 16:56
• Updated: 11/Nov/15 11:47
• Resolved: 11/Nov/15 11:47

Description

Tomcat warns at SEVERE level about a ThreadLocal leak (AsyncLogger$Info).

Steps to reproduce:

• Make all loggers async by using the AsyncLoggerContextSelector
• Place the log4j jar files in the web app's WEB-INF/lib folder, and the configuration file in the class path or in a location configured in the web.xml
• Start the web app, trigger some logging, then stop the web app.

Tomcat will warn

SEVERE: The web application [webapp] created a ThreadLocal with key of type [org.apache.logging.log4j.core.async.AsyncLogger$Info$1] (value [org.apache.logging.log4j.core.async.AsyncLogger$Info$1@136a1c9]) and a value of type [org.apache.logging.log4j.core.async.AsyncLogger.Info] (value [org.apache.logging.log4j.core.async.AsyncLogger$Info@597fb9]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.

Issue Links

• is part of: LOG4J2-323 ThreadLocal-leak on tomcat shutdown when using async logging
• relates to: LOG4J2-493 Problem with AsyncLogger when web app is deployed/undeployed multiple times