title: Jenkins crashes randomly with no warning
body: <p>I'm running Jenkins as a service on a Ubuntu server and it has been recently crashing.  My server has 512 MB of RAM with 256 MB allocated to Jenkins.  I checked the logs, but no traces of crashing have been recorded in there, so I suspect that Jenkins terminates immediately in each crash.  </p>
  
  <p>I recently tested the uptime of Jenkins, and it crashes between 2 to 15 minutes of being online.  I also tested the memory used, and Jenkins uses 120 MB of RAM to 160 MB of RAM.  Is there a way to fix this?</p>
  
  <p>Edit: I'm using Oracle JDK 7.</p>