IV16870: JAVA JIT - UNEXPECTED NULLPOINTEREXCEPTION

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APAR status

  • Closed as program error.

Error description

  • Error Message: NullPointerException
    .
    Stack Trace:
    While not specific to the following code, we have seen a number
    of cases where the problem involed the following classes on the
    stack when the exception occurred: .
    
    at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:290)
    at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:191)
    
    (additional stack-frames may appear before or after the above
    lines)
    
    The problem does not exist in Java5. In most cases this problem
    will result in a
    NullPointerException. This is due to the fact that most
    constructors which initialize the same variable twice will first
    initialize to NULL then change it in a super class constructor
    to something non-null.
    

Local fix

  • -Xjit:disableLookahead
    Note: Using this option will have a small effect on performance.
    

Problem summary

  • The JIT fails to set-up correct aliasing information when
    inlining a constructor (<init>) method where the constructor
    calls a super class constructor and both constructors set the
    same class variable using different classes. i.e. B extends A, A
    has a field called 'var' but B does not define it's own 'var'.
    Therefore A.var and B.var both refer to the same variable. In
    this case there is the potential for the JIT to propagate the
    first initialization of A.var into later uses of A.var despite
    the fact that the variable is set to a new value using B.var
    before the use of A.var.
    

Problem conclusion

  • This defect will be fixed in:
    6.0.1 SR1
    6.0.0 SR10
    .
    The JIT was modified to prevent this problem from occurring.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV16870

  • Reported component name

    JIT

  • Reported component ID

    620700124

  • Reported release

    260

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-03-10

  • Closed date

    2012-03-10

  • Last modified date

    2012-05-25

  • 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

  • R600 PSY

       UP



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Document information


More support for:

Runtimes for Java Technology
Just In Time (JIT) Compiler

Software version:

260

Reference #:

IV16870

Modified date:

2012-05-25

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