8317960: [17u] Excessive CPU usage on AbstractQueuedSynchronized.isEn…

…queued Reviewed-by: phh
openjdk · Nov 29, 2023 · 14e6812 · 14e6812 · openjdk-notifier · Nov 29, 2023
1 parent 78cc634
commit 14e6812
Show file tree

Hide file tree

Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedLongSynchronizer.java b/src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedLongSynchronizer.java
@@ -1156,7 +1156,9 @@ private long enableWait(ConditionNode node) {
          */
         private boolean canReacquire(ConditionNode node) {
             // check links, not status to avoid enqueue race
-            return node != null && node.prev != null && isEnqueued(node);
+            Node p; // traverse unless known to be bidirectionally linked
+            return node != null && (p = node.prev) != null &&
+                (p.next == node || isEnqueued(node));
         }
 
         /**

diff --git a/src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedSynchronizer.java b/src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedSynchronizer.java
@@ -1524,7 +1524,9 @@ private int enableWait(ConditionNode node) {
          */
         private boolean canReacquire(ConditionNode node) {
             // check links, not status to avoid enqueue race
-            return node != null && node.prev != null && isEnqueued(node);
+            Node p; // traverse unless known to be bidirectionally linked
+            return node != null && (p = node.prev) != null &&
+                (p.next == node || isEnqueued(node));
         }
 
         /**