title: Get stacktrace from stuck python process that does not accept signals
body: <p>I have to run a legacy Zope2 website and have some grievance with it. The biggest issue is that, occasionally, it just locks up, running at 100% CPU load and not answering to requests anymore. While the problem isn't reproducible on a regular basis, one page containing 3 dynamic graphs triggers it sometimes, so I suspect some kind of race condition that leads to an endless loop or a stuck busywait.</p>
  
  <p>The problem is, I have not yet found a way to debug this thing. There's nothing in the Zope logs and nothing in the system logs. I tried the suggestions from <a href="https://stackoverflow.com/questions/132058/getting-stack-trace-from-a-running-python-application">this question</a> to get a stacktrace, but the only signal that has any effect is <code>SIGKILL</code>.</p>
  
  <p>Is there another possibility to find out where exactly the process is when it gets stuck?</p>