I have the warnings plugin configured to scan the console log with "GNU compiler 4 (gcc)" only.
Most of the times my builds stay stuck when the plugin is scanning the console log. The last message that I see in the console log is:

[WARNINGS] GNU compiler 4 (gcc) : Found 4 warnings.

The build is running on a slave, this jobs have a shared workspace with lots of files (svn checkout is done in the workspace and it's a huge project).

There seems to be a deadlock during scanning of the workspace files. The jstack is in attachment.