On Mar 9, 2010, at 7:13 PM, Paul Hoadley wrote:
Hi Kieran,
On 10/03/2010, at 1:32 PM, Kieran Kelleher wrote:
Use jstack to see the stack traces of the deadlocked request threads.
I've never used jstack before, so I'm fairly unfamiliar with what
it's telling me. I'll paste the full output at the end, but I don't
think it found anything useful.
Also Wonder has a SessionDeadlock detection feature that is useful
to trap session deadlocks, report them and fix them. I have found
that to be the most useful way to find bugs that cause sesion
deadlocks.
Do you recall where in Wonder I can find that?
I think it is set by properties, IIRC.
-- jstack output --
Thread 7218: (state = BLOCKED)
- java.lang.Object.wait(long) @bci=0 (Compiled frame; information
may be imprecise)
Error occurred during stack walking:
java.lang.NullPointerException
at sun.jvm.hotspot.runtime.Frame.addressOfStackSlot(Frame.java:224)
at
sun
.jvm
.hotspot.runtime.x86.X86Frame.senderForCompiledFrame(X86Frame.java:
342)
at sun.jvm.hotspot.runtime.x86.X86Frame.sender(X86Frame.java:283)
at sun.jvm.hotspot.runtime.Frame.sender(Frame.java:194)
at sun.jvm.hotspot.runtime.Frame.realSender(Frame.java:199)
at sun.jvm.hotspot.runtime.VFrame.sender(VFrame.java:119)
at
sun.jvm.hotspot.runtime.CompiledVFrame.sender(CompiledVFrame.java:168)
at sun.jvm.hotspot.runtime.VFrame.javaSender(VFrame.java:146)
at sun.jvm.hotspot.tools.StackTrace.run(StackTrace.java:76)
at sun.jvm.hotspot.tools.StackTrace.run(StackTrace.java:45)
at sun.jvm.hotspot.tools.JStack.run(JStack.java:60)
at sun.jvm.hotspot.tools.Tool.start(Tool.java:221)
at sun.jvm.hotspot.tools.JStack.main(JStack.java:86)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun
.reflect
.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun
.reflect
.DelegatingMethodAccessorImpl
.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at sun.tools.jstack.JStack.runJStackTool(JStack.java:118)
at sun.tools.jstack.JStack.main(JStack.java:84)
Those threads look odd. Did you do an optimized build without debug
info? That is the only explanation that comes to mind. Either these
are hiding the actual stack trace, or the problem is an exception
thrown from sleep() or terminate().
Chuck
--
Chuck Hill Senior Consultant / VP Development
Practical WebObjects - for developers who want to increase their
overall knowledge of WebObjects or who are trying to solve specific
problems.
http://www.global-village.net/products/practical_webobjects
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