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changeset 187:14ea8c5a07c9

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Bug 3225: JVM may hang when deadlock detector and safepoint are conflicted Reviewed-by: ykubota https://github.com/HeapStats/heapstats/pull/48
author Yasumasa Suenaga <yasuenag@gmail.com>
date Wed, 09 Nov 2016 21:15:19 +0900
parents 9798887d2ade
children 44059a9aa639
files ChangeLog agent/src/heapstats-engines/deadlockFinder.cpp
diffstat 2 files changed, 15 insertions(+), 2 deletions(-) [+]
line wrap: on
line diff
--- a/ChangeLog	Tue Nov 08 22:34:43 2016 +0900
+++ b/ChangeLog	Wed Nov 09 21:15:19 2016 +0900
@@ -1,3 +1,7 @@
+2016-11-09  Yasumasa Suenaga <yasuenag@gmail.com>
+
+	* Bug 3225: JVM may hang when deadlock detector and safepoint are conflicted
+
 2016-11-08  Yasumasa Suenaga <yasuenag@gmail.com>
 
 	* Bug 3223: Cannot set empty value to signal setting
--- a/agent/src/heapstats-engines/deadlockFinder.cpp	Tue Nov 08 22:34:43 2016 +0900
+++ b/agent/src/heapstats-engines/deadlockFinder.cpp	Wed Nov 09 21:15:19 2016 +0900
@@ -358,6 +358,17 @@
   }
 
   if (*status == THREAD_IN_VM) {
+    /*
+     * Reset "_thread_state".
+     *
+     * CAUTION!!
+     *   According to the comment of Monitor::lock_without_safepoint_check() in
+     *   hotspot/src/share/vm/runtime/mutex.cpp:
+     *     If this is called with thread state set to be in VM, the safepoint
+     *     synchronization code will deadlock!
+     */
+    *status = original_status;
+
     bool needLock = !vmFunc->MonitorOwnedBySelf(thread_lock);
 
     /*
@@ -373,8 +384,6 @@
       }
     }
 
-    /* Reset "_thread_state". */
-    *status = original_status;
     /* Reset "_safepoint_state". */
     vmFunc->ThreadSafepointStateDestroy(thisThreadPtr);
     vmFunc->ThreadSafepointStateCreate(thisThreadPtr);