[8u] 8218558: NMT stack traces in output should show mt component for virtual memory allocations

[Andrew John Hughes]

On 22/08/2019 12:40, Zhengyu Gu wrote:
> Hi,
> 
> I would like to backport this patch to 8u.
> 
> It is the counterpart of JDK-8139673, that improves usability of NMT
> detail tracking, by associating every virtual memory allocation site
> with its memory type.
> 
> 11u patch does not apply cleanly, but conflicts are minors. There are a
> couple of conflicts with copyright years, also a new include file in 11u
> patch that already added in 8u, and indents.
> 
> Original bug: https://bugs.openjdk.java.net/browse/JDK-8218558
> Original code review thread:
> https://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2019-February/032428.html
> 
> 
> 8u Webrev:
> http://cr.openjdk.java.net/~zgu/JDK-8218558-8u/webrev.00/index.html
> 
> 
> Thanks,
> 
> -Zhengyu

There is another conflict you didn't mention, visible when comparing the
two patches:

@@ -160,15 +152,20 @@

  void MemDetailDiffReporter::diff_malloc_site(const MallocSite* early,
    const MallocSite* current)  const {
--  assert(early->flags() == current->flags(), "Must be the same memory
type");
-+  assert(early->flag() == current->flag(), "Must be the same memory
type");
-   diff_malloc_site(current->call_stack(), current->size(),
current->count(),
--    early->size(), early->count(), early->flags());
-+    early->size(), early->count(), early->flag());
+-  if (early->flags() != current->flags()) {
++  if (early->flag() != current->flag()) {
+     // If malloc site type changed, treat it as deallocation of old
type and
+     // allocation of new type.
+     old_malloc_site(early);
+     new_malloc_site(current);
+   } else {
+     diff_malloc_site(current->call_stack(), current->size(),
current->count(),
+-      early->size(), early->count(), early->flags());
++      early->size(), early->count(), early->flag());
+   }
  }

- void MemDetailDiffReporter::diff_malloc_site(const NativeCallStack*
stack, size_t current_size,

This is a sequencing issue. 8u already has '8200109: NMT:
diff_malloc_site assert(early->flags() == current->flags(), "Must be the
same memory type")', which was applied after 8218558. Once both patches
are applied to 8u, the function looks the same in both 8u & 13u.

Reviewed & approved.

Thanks,
-- 
Andrew :)

Senior Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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