IBM Support

IV83044: JIT INCORRECTLY PRIORITIZES CERTAIN CODEPATHS

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APAR status

  • Closed as program error.

Error description

  • Error Message: Report of Performance Degradation between IBM
Java 8 SR1 and SR2
.
Stack Trace: N/A
.

Local fix

  • N/A

Problem summary

  • The JIT optimizer is guided by execution frequency information
calculated from runtime profiling information. In some
circumstances the JIT can misinterpret profiling information
leading to certain codepaths looking artificially more important
than they should. This can lead to changes in optimization
decisions that cause a performance regression.

Problem conclusion

  • The frequency computation logic has been improved to ensure
computed frequencies more closely match execution behaviour
which helps the JIT to make better optimization decisions.
.
This APAR will be fixed in the following Java Releases:
   8    SR3       (8.0.3.0)
.
Contact your IBM Product's Service Team for these Service
Refreshes and Fix Packs.
For those running stand-alone, information about the available
Service Refreshes and Fix Packs can be found at:
           https://www.ibm.com/developerworks/java/jdk/

Temporary fix

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    IV83044
    • 

  • Reported component name
    JIT
    • 

  • Reported component ID
    620700124
    • 

  • Reported release
    130
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt / Xsystem
    • 

  • Submitted date
    2016-03-24
    • 

  • Closed date
    2016-03-24
    • 

  • Last modified date
    2016-03-24
    • 





    

  • 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


    

  • R130  PSY
       UP
    • 








      
              
                            

              

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Document Information


            

            


                        

            Modified date:
            

            24 March 2016
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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