In our quick build server today we are seeing an odd set of circumstances, this has occurred 3 times in the last 12 hours:
1. Jobs currently in progress stop progressing - Jobs collecting metrics stick in that state, jobs checking for build condition stick there, and job running steps stick there
2. All newly triggered jobs stay queued with Waiting_Process

The only thing that seems to resolve the issue is a Quickbuild service restart which interrupts our production job runs

Can you have a look at the logs and thread dumps we have and see if you can pinpoint what is going on?