Does CollectedHeap::print_on() need Heap_lock?

[Yasumasa Suenaga]

Hi all,

I have a question about Heap_lock in Universe::print_*().

Universe::print_heap_at_SIGBREAK() gets Heap_lock.
However, HeapInfoDCmd::execute() and Universe::print_on() do not get Heap_lock.

Should we get Heap_lock when we print heap information?
I guess that we should get this lock for consistency.

--------------------
diff -r 87215e99d945 src/share/vm/memory/universe.cpp
--- a/src/share/vm/memory/universe.cpp  Wed Apr 06 23:42:52 2016 +0000
+++ b/src/share/vm/memory/universe.cpp  Tue Apr 12 22:23:17 2016 +0900
@@ -1069,6 +1069,7 @@
 }

 void Universe::print_on(outputStream* st) {
+  MutexLocker hl(Heap_lock);
   st->print_cr("Heap");
   heap()->print_on(st);
 }
diff -r 87215e99d945 src/share/vm/services/diagnosticCommand.cpp
--- a/src/share/vm/services/diagnosticCommand.cpp       Wed Apr 06 23:42:52 2016 +0000
+++ b/src/share/vm/services/diagnosticCommand.cpp       Tue Apr 12 22:23:17 2016 +0900
@@ -413,6 +413,7 @@
 }

 void HeapInfoDCmd::execute(DCmdSource source, TRAPS) {
+  MutexLocker hl(Heap_lock);
   Universe::heap()->print_on(output());
 }

--------------------

If it is correct, I file it to JBS and send review request.


Thanks,

Yasumasa