Jetty

NPE in SelectorManager

Details

  • Type: Bug Bug
  • Status: Resolved Resolved
  • Priority: Minor Minor
  • Resolution: Fixed
  • Affects Version/s: 6.1.3
  • Fix Version/s: 7.0.0pre2, 6.1.11
  • Component/s: NIO
  • Labels:
    None
  • Environment:
    JDK 1.6.0
  • Number of attachments :
    0

Description

We're getting this intermittent NullPointerExceptions in our unit tests when doing the org.mortbay.jetty.Server.stop():

[junit] java.lang.NullPointerException
[junit] at org.mortbay.io.nio.SelectorManager.doStop(SelectorManager.java:211)
[junit] at org.mortbay.component.AbstractLifeCycle.stop(AbstractLifeCycle.java:65)
[junit] at org.mortbay.jetty.nio.SelectChannelConnector.doStop(SelectChannelConnector.java:320)
[junit] at org.mortbay.component.AbstractLifeCycle.stop(AbstractLifeCycle.java:65)
[junit] at org.mortbay.jetty.Server.doStop(Server.java:267)
[junit] at org.mortbay.component.AbstractLifeCycle.stop(AbstractLifeCycle.java:65)

Could it be a chance of having a race in the doStop() when one thread has nullified the _selectSet and the other is accessing it?

    protected void doStop() throws Exception
    {
        for (int i=0;i<_selectSet.length;i++)
            _selectSet[i].stop();                  // <------ line #211 of SelectorManager.java
        super.doStop();
        _selectSet=null;
    }

Activity

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Greg Wilkins added a comment -

We had done some work after 6.1.3 to avoid dual calls to stop, but as there is no harm in some defensive programming, I have also restructured stop to avoid the NPE.

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Greg Wilkins added a comment - We had done some work after 6.1.3 to avoid dual calls to stop, but as there is no harm in some defensive programming, I have also restructured stop to avoid the NPE.
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Matthew Kwong added a comment -

Thank you so much!

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Matthew Kwong added a comment - Thank you so much!
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Ole Matzura added a comment -

Hi,

I'm still getting this, but now on the inner

sets[i].stop();

call.. I've modified the loop to be

for (int i=0;i<sets.length;i++)
if( sets[i] != null )
sets[i].stop();

which fixes the problem for me (using 6.1.8)

regards!

/Ole
eviware.com

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Ole Matzura added a comment - Hi, I'm still getting this, but now on the inner sets [i] .stop(); call.. I've modified the loop to be for (int i=0;i<sets.length;i++) if( sets [i] != null ) sets [i] .stop(); which fixes the problem for me (using 6.1.8) regards! /Ole eviware.com
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Greg Wilkins added a comment -

Up for grabs

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Greg Wilkins added a comment - Up for grabs
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Greg Wilkins added a comment -

Athena, Can you check if this is still an issue and if the proposed fix is valid.

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Greg Wilkins added a comment - Athena, Can you check if this is still an issue and if the proposed fix is valid.
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Greg Wilkins added a comment -

fixed

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Greg Wilkins added a comment - fixed

People

  • Assignee:
    Athena Yao
    Reporter:
    Matthew Kwong
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Dates

  • Created:
    Updated:
    Resolved: