8189360: JvmtiExport::weak_oops_do is called for all JNIHandleBlock instances

[Per Liden]

Hi,

On 2017-10-16 17:40, Stefan Karlsson wrote:
> Hi all,
> 
> Please review this patch to move the call of the static 
> JvmtiExport::weak_oops_do out of the JNIHandleBlock::weak_oops_do member 
> function into the new WeakProcessor.
> 
> Today, this isn't causing any bugs because there's only one instance of 
> JNIHandleBlock, the _weak_global_handles. However, in prototypes with 
> more than one JNIHandleBlock, this results in multiple calls to 
> JvmtiExport::weak_oops_do.
> 
> http://cr.openjdk.java.net/~stefank/8189360/webrev.00/
> https://bugs.openjdk.java.net/browse/JDK-8189360

   30 void WeakProcessor::unlink_or_oops_do(BoolObjectClosure* is_alive, 
OopClosure* keep_alive, VoidClosure* complete) {
   31   JNIHandles::weak_oops_do(is_alive, keep_alive);
   32   if (complete != NULL) {
   33     complete->do_void();
   34   }
   35
   36   JvmtiExport::weak_oops_do(is_alive, keep_alive);
   37   if (complete != NULL) {
   38     complete->do_void();
   39   }
   40 }

Should you really be calling complete->do_void() twice here. It seems to 
me that doing it once, after both calls to weak_oops_do() would mimic 
what the old code did?

cheers,
Per

> 
> This patch builds upon the patch in:
> http://mail.openjdk.java.net/pipermail/hotspot-dev/2017-October/028684.html
> 
> Tested with JPRT.
> 
> Thanks,
> StefanK