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  1. Cocoon
  2. COCOON-1261

Too Many File handles open



    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Incomplete
    • Affects Version/s: 2.1.4
    • Fix Version/s: None
    • Component/s: * Cocoon Core
    • Labels:
    • Environment:
      Operating System: Linux
      Platform: Other
    • Bugzilla Id:


      We have a cocoon instance running in production serving an application. When
      search engines or a large number of users hit the site we see the number of open
      file handles rising. Most of the time this is Ok, however sometimes the whole
      JVM crashes with a Too many file handles open exceptiom. The only reason I have
      marked this as critical, it that when the JVM goes down, all the users start
      complaining, and this is a production system.

      The Operations guys are saying there is a potential Denial Of Service problem as
      a result

      We have done some investigation with a very simple pipeline, that generates from
      an xml file, and transforms (xslt) doing a document() XPath lookup into annother
      file, then serialises the result. We would have expected to see 1 file handle
      per file, per thead, ie 2 per thread. We ran the load test with 50 threads and
      no delays.

      1. Using lsof on the Jvm process group for Tomcat we see between 2000 and 4000
      filehandles open to the files referenced in the pipeline.
      2. The number open appears to follow garbage collection cycles, ie drops when
      garbage collection is performed.
      3. When the load is taken off, the total soon returns to 0.

      1. It looks like the file handles are not being released (at the OS level) until
      garbage collection takes place.
      2. If this is true is there any way of ensuring earlier release ?

      Things we dont want to do (partially because we dont have to do them with the
      other non Cocoon applications in production)

      1. Vastly increase the File Handle limits on the machine.
      2. Reduce the size of the JVM heap to ensure there can never be too many File
      objects in existance. (currently ~ 1.5GB)
      3. perform agressive garbage collection.

      Is this an issue for cocoon ? Or is it a wider problem with Java, GC and OS
      resources on heavilly loaded systems ?




            • Assignee:
              ieb@tfd.co.uk Ian Boston
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              • Created: