How to add the Process id to a LOG4J log file?

Question

I currently have the below pattern layout in log4j. I want to add the Process id to the log file. How can I do it?

log4j.appender.A1.layout=org.apache.log4j.Pa         


        

Answer 1

You should use MDC to do it

In the config file :

log4j.appender.stdout.layout.ConversionPattern=%d{yyyy/MM/dd HH:mm:ss}  %-5p  (%c) %m%n %X{PID}

%X{PID} is used to match the context value PID

And then, in the code, before the logging begins :

log4j 1.x

RuntimeMXBean rt = ManagementFactory.getRuntimeMXBean();
String pid = rt.getName();
MDC.put("PID", pid);

log4j 2.x

RuntimeMXBean rt = ManagementFactory.getRuntimeMXBean();
String pid = rt.getName();
ThreadContext.put("PID", pid);