[15] RFR(XS): 8244946: fatal error: memory leak: allocating without ResourceMark with -XX:+Verbose -Xlog:methodhandles

[Daniel D. Daugherty]

On 5/13/20 11:10 AM, Christian Hagedorn wrote:
> Hi
>
> Please review the following patch:
> https://bugs.openjdk.java.net/browse/JDK-8244946
> http://cr.openjdk.java.net/~chagedorn/8244946/webrev.00/

src/hotspot/cpu/x86/methodHandles_x86.cpp
     I was looking at your expanded scope and I happened to see:

         L525:       PRESERVE_EXCEPTION_MARK; // may not be needed by 
safer and unexpensive here

     Not your bug, but the comment has two typos:

         s/by safer/but safer/
         s/unexpensive/inexpensive/

     So your expanded scope now extends the PRESERVE_EXCEPTION_MARK over
     this block:

         L571:       if (has_mh && oopDesc::is_oop(mh)) {
         L572:         mh->print();
         L573:         if (java_lang_invoke_MethodHandle::is_instance(mh)) {
         L574:           if 
(java_lang_invoke_MethodHandle::form_offset_in_bytes() != 0) {
         L575: java_lang_invoke_MethodHandle::form(mh)->print();
         L576:           }
         L577:         }
         L578:       }

     I don't see anything worrisome about extending the
     PRESERVE_EXCEPTION_MARK, but I'm not really an invoke/MethodHandle
     expert here. :-)

src/hotspot/share/oops/klass.cpp
     No comments.

test/hotspot/jtreg/runtime/logging/TestMethodHandlesVerbose.java
     Thanks for including a test.


Thumbs up.

Dan


>
> This simply fixes a missing ResourceMark required to call 
> Klass::oop_print_on().
>
> The reason for the missing ResourceMark in oop_print_on() is stated in 
> the RFR [1] for JDK-8222893 [2] which removed the ResourceMark due to 
> a bug:
>
> "print functions with outputStream should not have a ResourceMark 
> because you could call it with a LogStream or stream that was 
> allocated outside the resource mark. The caller needs the ResourceMark."
>
> There are other places like Klass::print_on(outputStream*) where this 
> is still the case. Should we file an RFE to clean these up?
>
> Thank you!
>
> Best regards,
> Christian
>
>
> [1] 
> https://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2019-May/034095.html
> [2] https://bugs.openjdk.java.net/browse/JDK-8222893