Maven (mvn) build hanging

I recently had a problem with a maven build hanging when doing a ‘mvn install’.

I found some pointers in this post, and posting here in a modified form: http://forum.spring.io/forum/spring-projects/roo/121725-what-diagnostic-action-to-take-when-maven-hangs

1. In the hanging shell, hit CTRL-Z – this will suspend the program and give you a pid. An alternative way to get the pid is to do a “ps -ef” and search for you mvn command e.g. “clean install”
2. type bg [ENTER] – this will send the program to the background
3. Do a kill -3 of the process – it will dump a large amount of text – make sure your command line terminal history window is long enough to capture it all – will be several thousand lines of text
(alternative to #3 – you can try jstack with the pid, it is a Java stack trace generator)
4. You can see what threads are waiting on other threads from there (maybe, sometimes it’s a tight CPU loop)

Tags: Maven, mvn