Remove more pointer chasing in tight loops

jbossas · Sep 26, 2024 · 4ab166b · 4ab166b
1 parent 7099668
commit 4ab166b
Showing 1 changed file with 9 additions and 7 deletions.
diff --git a/src/main/java/org/jboss/threads/EnhancedQueueExecutor.java b/src/main/java/org/jboss/threads/EnhancedQueueExecutor.java
@@ -916,18 +916,19 @@ public void shutdown() {
     public List<Runnable> shutdownNow() {
         shutdown(true);
         final ArrayList<Runnable> list = new ArrayList<>();
-        TaskNode head = getHead();
+        TaskNode[] unsharedTaskNodes = this.unsharedTaskNodes;
+        TaskNode head = getHead(unsharedTaskNodes);
         QNode headNext;
         for (;;) {
             headNext = head.getNext();
             if (headNext == head) {
                 // a racing consumer has already consumed it (and moved head)
-                head = getHead();
+                head = getHead(unsharedTaskNodes);
                 continue;
             }
             if (headNext instanceof TaskNode) {
                 TaskNode taskNode = (TaskNode) headNext;
-                if (compareAndSetHead(head, taskNode)) {
+                if (compareAndSetHead(unsharedTaskNodes, head, taskNode)) {
                     // save from GC nepotism
                     head.setNextOrdered(head);
                     if (getQueueLimited()) decreaseQueueSize();
@@ -1596,14 +1597,15 @@ public void run() {
 
     private void runThreadBody() {
         final LongAdder spinMisses = this.spinMisses;
+        TaskNode[] unsharedTaskNodes = this.unsharedTaskNodes;
         // Eagerly allocate a PoolThreadNode for the next time it's needed
         PoolThreadNode nextPoolThreadNode = new PoolThreadNode(currentThread());
         // main loop
         processingQueue: for (;;) {
             TaskNode head;
             QNode headNext;
             for (;;) {
-                head = getHead();
+                head = getHead(unsharedTaskNodes);
                 headNext = head.getNext();
                 // headNext == head can happen if another consumer has already consumed head:
                 // retry with a fresh head
@@ -1686,7 +1688,7 @@ private void runThreadBody() {
                             nextPoolThreadNode.setNextRelaxed(null);
                         }
                     } else if (headNext instanceof TaskNode taskNode) {
-                        if (compareAndSetHead(head, taskNode)) {
+                        if (compareAndSetHead(unsharedTaskNodes, head, taskNode)) {
                             // save from GC Nepotism: generational GCs don't like
                             // cross-generational references, so better to "clean-up" head::next
                             // to save dragging head::next into the old generation.
@@ -2020,7 +2022,7 @@ boolean compareAndSetTail(final EnhancedQueueExecutor.TaskNode expect, final Enh
         return getTail() == expect && unsafe.compareAndSwapObject(unsharedTaskNodes, RuntimeFields.tailOffset, expect, update);
     }
 
-    TaskNode getHead() {
+    TaskNode getHead(final TaskNode[] unsharedTaskNodes) {
         return (TaskNode) unsafe.getObjectVolatile(unsharedTaskNodes, RuntimeFields.headOffset);
     }
 
@@ -2029,7 +2031,7 @@ TaskNode setHeadPlain(TaskNode head) {
         return head;
     }
 
-    boolean compareAndSetHead(final EnhancedQueueExecutor.TaskNode expect, final EnhancedQueueExecutor.TaskNode update) {
+    boolean compareAndSetHead(final TaskNode[] unsharedTaskNodes, final TaskNode expect, final TaskNode update) {
         return unsafe.compareAndSwapObject(unsharedTaskNodes, RuntimeFields.headOffset, expect, update);
     }