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IV34348: GETLOADEDCLASSES() WITH SRT CAUSED CRASHES IN GC

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • Error Message: Unhandled exception
Type=Segmentation error vmState=0x00020002
J9Generic_Signal_Number=00000004 Signal_Number=0000000b
Error_Value=00000000 Signal_Code=00000001
Handler1=F6D38D09 Handler2=F6CF9257 InaccessibleAddress=0000000C
EDI=00000001 ESI=00000000 EAX=080708F0 EBX=F62FA200
ECX=D9E90390 EDX=08070880
EIP=F61FDF9E ES=002B DS=002B ESP=938D8FA0
EFlags=00010246 CS=0023 SS=002B EBP=938D90A8
Module=/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270s
r3-20121025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.s
o
Module_base_address=F614D000
Target=2_60_20121024_126071 (Linux 3.0.38-0.5-default)
CPU=x86 (4 logical CPUs) (0xf7926000 RAM)
.
Stack Trace: p> 20121102-14:39:22 <gdb> #0  0xf6c5e8fa in
j9dump_create () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-
i386-70/jre/lib/i386/default/libj9prt26.so
p> 20121102-14:39:22 <gdb> #1  0xf699ae4e in doSystemDump ()
from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-
i386-70/jre/lib/i386/default/libj9dmp26.so
p> 20121102-14:39:22 <gdb> #2  0xf6999627 in
protectedDumpFunction () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-
20121025_01/ibm-java-i386-70/jre/lib/i386/default/libj9dmp26.so
p> 20121102-14:39:22 <gdb> #3  0xf6c6e202 in j9sig_protect ()
from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-
i386-70/jre/lib/i386/default/libj9prt26.so
p> 20121102-14:39:22 <gdb> #4  0xf69995f8 in runDumpFunction ()
from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-
java-i386-70/jre/lib/i386/default/libj9dmp26.so
p> 20121102-14:39:22 <gdb> #5  0xf699e555 in runDumpAgent ()
from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-
i386-70/jre/lib/i386/default/libj9dmp26.so
p> 20121102-14:39:22 <gdb> #6  0xf69b1947 in triggerDumpAgents
() from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-
java-i386-70/jre/lib/i386/default/libj9dmp26.so
p> 20121102-14:39:22 <gdb> #7  0xf6cac197 in
generateDiagnosticFiles () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-
20121025_01/ibm-java-i386-70/jre/lib/i386/default/libj9vm26.so
p> 20121102-14:39:22 <gdb> #8  0xf6c6e202 in j9sig_protect ()
from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-
i386-70/jre/lib/i386/default/libj9prt26.so
p> 20121102-14:39:22 <gdb> #9  0xf6cac3ae in vmSignalHandler ()
from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-
java-i386-70/jre/lib/i386/default/libj9vm26.so
p> 20121102-14:39:22 <gdb> #10 0xf6caccc8 in
structuredSignalHandler () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-
20121025_01/ibm-java-i386-70/jre/lib/i386/default/libj9vm26.so
p> 20121102-14:39:22 <gdb> #11 0xf6cacd3b in
structuredSignalHandlerForJavaVM () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-
20121025_01/ibm-java-i386-70/jre/lib/i386/default/libj9vm26.so
p> 20121102-14:39:22 <gdb> #12 0xf6c6d425 in
masterSynchSignalHandler () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-
20121025_01/ibm-java-i386-70/jre/lib/i386/default/libj9prt26.so
p> 20121102-14:39:22 <gdb> #13 <signal handler called>
p> 20121102-14:39:22 <gdb> #14 0xf6171f9e in
MM_RealtimeMarkingScheme::incrementalConsumeQueue(MM_Environment
Realtime*, unsigned int) () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #15 0xf615e9ed in
MM_StaccatoGC::doTracing(MM_EnvironmentRealtime*) () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #16 0xf61753ad in
MM_RealtimeMarkingScheme::markLiveObjects(MM_EnvironmentRealtime
*) () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #17 0xf6171b9d in
MM_RealtimeMarkTask::run(MM_EnvironmentModron*) () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #18 0xf622749e in
MM_Dispatcher::run(MM_EnvironmentModron*, MM_Task*) () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #19 0xf61711b9 in
MM_RealtimeGC::incrementalCollect(MM_EnvironmentRealtime*) ()
from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #20 0xf617154b in
MM_RealtimeGC::internalGarbageCollect(MM_EnvironmentModron*,
MM_MemorySubSpace*,
MM_AllocateDescription*) () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-i386-
70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #21 0xf60e6705 in
MM_Collector::garbageCollect(MM_EnvironmentModron*,
MM_MemorySubSpace*, MM_AllocateDescription*,
unsigned int, MM_ObjectAllocationInterface*, MM_MemorySubSpace*,
MM_AllocationContext*) () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #22 0xf616a896 in
MM_MemorySubSpaceMetronome::collect(MM_EnvironmentModron*,
MM_GCCode) () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #23 0xf617c365 in
MM_Scheduler::masterEntryPoint(MM_EnvironmentModron*) () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #24 0xf623ea94 in
dispatcher_thread_proc2(J9PortLibrary*, void*) () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #25 0xf6c6e202 in j9sig_protect ()
from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-java-
i386-70/jre/lib/i386/default/libj9prt26.so
p> 20121102-14:39:22 <gdb> #26 0xf623e075 in
dispatcher_thread_proc () from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-
20121025_01/ibm-java-i386-70/jre/lib/i386/default/libj9gc26.so
p> 20121102-14:39:22 <gdb> #27 0xf77301e5 in thread_wrapper ()
from
/jtctest/sdk_installs_hc/ESPRESSO/PKG/pxi3270sr3/pxi3270sr3-2012
1025_01/ibm-
java-i386-70/jre/lib/i386/default/libj9thr26.so
p> 20121102-14:39:22 <gdb> #28 0xf770a809 in start_thread ()
from /lib/libpthread.so.0
p> 20121102-14:39:22 <gdb> #29 0xf764f1be in clone () from
/lib/libc.so.6
.
This problem has been discovered by attaching a new version of
Health Center to VM and requesting loaded classes stats

Local fix

  • This issue might intermittently occur because of using
GetLoadedClasses() JNI call for VM running with
-Xgcpolicy:metronome (Soft Real Time) so it can be worked out by
using any other GC policy. If SRT is must to be used try to
avoid any functionality might call GetLoadedClasses() (run with
attached JVMTI agent for example)

Problem summary

  • In SRT (only) if JNI GetLoadedClasses() is called at the middle
of GC Cycle it might return classes which are technically alive
at the moment but about to die (to be unloaded) at the end of
this GC Cycle. Such classes might be added to the JNI Tables
(JNI Local References for instance) and be a reason for crash in
GC after classes unloading.

Problem conclusion

  • This defect will be fixed in:
6.0.1 SR5
7.0.0 SR4
.
The solution is to prevent classes listed in GetLoadedClasses()
output to be unloaded.

Temporary fix

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    IV34348
    • 

  • Reported component name
    J9 COMMON CODE
    • 

  • Reported component ID
    620700127
    • 

  • Reported release
    260
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt
    • 

  • Submitted date
    2013-01-08
    • 

  • Closed date
    2013-01-08
    • 

  • Last modified date
    2013-01-08
    • 





    

  • APAR is sysrouted FROM one or more of the following:
    

    • 

  • APAR is sysrouted TO one or more of the following:
    

    • 



Fix information


    

  • Fixed component name
    J9 COMMON CODE
    • 

  • Fixed component ID
    620700127
    • 



Applicable component levels


    

  • R260  PSY
       UP
    • 








      
              
                            

              

              [{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSNVBF","label":"Runtimes for Java Technology"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"6.1","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]
              

                          

          
 
        

      

    

      

        

          

            
Document Information


            

            


                        

            Modified date:
            

            21 February 2022
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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