[Mono-bugs] [Bug 652109] New: WebService consumes all CPU over time

bugzilla_noreply at novell.com bugzilla_noreply at novell.com
Mon Nov 8 12:19:45 EST 2010



           Summary: WebService consumes all CPU over time
    Classification: Mono
           Product: Mono: Runtime
           Version: 2.6.x
          Platform: x86
        OS/Version: Other
            Status: NEW
          Severity: Major
          Priority: P5 - None
         Component: misc
        AssignedTo: mono-bugs at lists.ximian.com
        ReportedBy: mgoodwin at noblesys.com
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---
           Blocker: ---

Created an attachment (id=399010)
 --> (http://bugzilla.novell.com/attachment.cgi?id=399010)
An strace pulled during the time of the error.

User-Agent:       Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64;
Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729;
OfficeLiveConnector.1.5; OfficeLivePatch.1.3; .NET4.0C)

The operating system is Centos 5.4 running Apache 2.2.3-43.e15.centos under
mono 2.6.4 (tarball Jul 20 2010).

After a period of 24-72 hours of running mod mono, the process will consume all
available cores on the system regardless of usage.  The average load is around
800 requests a second to a webservice.   During testing, the webservice was
simplified to contain a thread sleep of 50 millisconds and return an empty
generic list as follows:

public List<MyObj> GetValues()
    return new List<MyObj>();

Removing the Thread.Sleep appears to allow the service to run for a period of
over a week but eventually top will indicate mono consuming most, if not all,
cores on the system.

Note:  Recycling of mono is not configured for the site and there is no cron
job recycling apache/mono nightly.  

Hardware Information for test server:

CPU:  Intel(R) Xeon(R) CPU  X5680  @ 3.33GHz (24 core)
Memory:  16GB

<<Strace during failure attached>>

Reproducible: Always

Steps to Reproduce:
1. Simulate web service requests at a rate of 800/sec to the service as
described above.
2. Allow to run for a period 72 hours.

Actual Results:  
Top indicates cpu usage equal to 90 percent+ of the overall processing power.  

Expected Results:  
No unexplained increase in CPU.

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