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IV19959: NON-ATOMIC VARIABLE-LENGTH ARRAYCOPIES

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APAR status

  • Closed as program error.

Error description

  • Error Message: N/A
.
Stack Trace: N/A
.

Local fix

  • This issue can be avoided using the -Xjit:disableArraycopyOpts
option. This option may cause a noticeable performance
degradation.

Problem summary

  • The inlined sequence for variable-length non-byte arraycopies
generated by the Java JIT Compiler includes a single-byte MVC
(move character) instruction to handle residual (<256 bytes)
elements.  As a result of this single byte copy, a partially
copied element value may be visible to other threads
concurrently examining that array.
This issue only impacts JDKs on Linux on Z and zOS.

Problem conclusion

  • This defect will be fixed in:
7.0.0 SR1
6.0.1 SR2
.
The JVM has been updated to remove the single-byte MVC
instruction and generate an atomic sequence for all reference
arraycopies.

Temporary fix

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    IV19959
    • 

  • Reported component name
    JIT
    • 

  • Reported component ID
    620700124
    • 

  • Reported release
    260
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt
    • 

  • Submitted date
    2012-04-20
    • 

  • Closed date
    2012-04-20
    • 

  • Last modified date
    2012-04-20
    • 





    

  • 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
    JIT
    • 

  • Fixed component ID
    620700124
    • 



Applicable component levels


    

  • R260  PSY
       UP
    • 








      
              
                            

              

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Document Information


            

            


                        

            Modified date:
            

            20 April 2012
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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