JDK-8043224 : -Xcheck:jni improvements to exception checking and excessive local refs
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: runtime
  • Affected Version: 9
  • Priority: P4
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2014-05-15
  • Updated: 2017-12-10
  • Resolved: 2014-06-11
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JDK 8 JDK 9
8u60Fixed 9 b22Fixed
Related Reports
Duplicate :  
JDK-6723450 - -verbose:jni or -Xcheck:jni do not report excessive local reference usage.
Relates :  
JDK-8164086 - Checked JNI pending exception check should be cleared when returning to Java frame
Relates :  
JDK-8160614 - Some of the checked JNI improvements are excessively verbose
Relates :  
JDK-8193222 - EnsureLocalCapacity() should maintain capacity requests through multiple calls
Relates :  
JDK-8046668 - Excessive checked JNI warnings from Java startup
Description
Summary of enhancements to checked JNI after a number mail discussions and related bugs:

1) Checked JNI to enforce calling "ExceptionOccurred()" or "ExceptionOccurred()" after using "Call*Method()" functions, before using further JNI functions. Warn if exception check not carried out before calling a method that does not allow pending exceptions. Subtle difference to the current "there is a pending exception" check, does the programmer actual call one of the check functions.

2) If a JNI method implicitly grew the local ref capacity beyond what was planned for, warn the user. This of course excludes PushLocalFrame or EnsureLocalCapacity.