IV53806: JVM HANGS WHEN ONE THREAD READS THE CLASS ATTRIBUTES ANOTHER THREAD MODIFIES THE DEFINITION OF THE CLASS

APAR status

• Closed as program error.

Error description

• Error Message: The JVM process hangs while one of the
  application thread busy executing within getter methods like
  Class.getDeclaredFields.
  .
  Stack Trace: Java stack of the application thread:
  java/lang/Class.getDeclaredFieldsImpl(Native Method)
  java/lang/Class.getDeclaredFields(Class.java:607)
  ...
  and corresponding native stack of the thread:
  romFieldsNextDo()
  getJNIFieldID()
  createInstanceFieldObject()
  java_lang_Class_getDeclaredFieldsImpl()
  ...
  .
  

Local fix

• This problem can be worked around by disabling any profilers
  like wily which have the capability to perform runtime
  modification of class definition(using JVMTI interfaces
  RetransformClasses and RedefineClasses).
  

Problem summary

• The problem is caused when the JVM executes reflect getter
  method on a class and at the same time another thread modifies
  the definition of the class using the JVMTI
  interfaces(RetransformClasses and RedefineClasses)
  

Problem conclusion

• This APAR will be fixed in the following Java Releases:
     6 R1 SR8       (6.1.8.0)
     7    SR7       (7.0.7.0)
     7 R1 SR1       (7.1.1.0)
     6    SR16      (6.0.16.0)
  .
  The JVM has been modified to handle the special condition
  between the JVMTI interfaces and the getter methods execution.
  

Temporary fix

Comments

APAR Information

• 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

• R270 PSY

     UP

• R600 PSY

     UP