waitQueue.compare_exchange_strong in the true loop can be weak

AZero13 · AZero13 · commit 331ecfbeff42 · 2023-12-27T10:54:03.000-05:00
weak is more suitable for this while loop than strong.
diff --git a/stdlib/public/Concurrency/TaskGroup.cpp b/stdlib/public/Concurrency/TaskGroup.cpp
@@ -1947,7 +1947,7 @@ void TaskGroupBase::waitAll(SwiftError* bodyError, AsyncTask *waitingTask,
       waitingTask->flagAsSuspendedOnTaskGroup(asAbstract(this));
     }
     // Put the waiting task at the beginning of the wait queue.
-    if (waitQueue.compare_exchange_strong(
+    if (waitQueue.compare_exchange_weak(
         waitHead, waitingTask,
         /*success*/ std::memory_order_release,
         /*failure*/ std::memory_order_acquire)) {

Original file line number	Diff line number	Diff line change
`@@ -1947,7 +1947,7 @@ void TaskGroupBase::waitAll(SwiftError* bodyError, AsyncTask *waitingTask,`
`1947`	`1947`	`waitingTask->flagAsSuspendedOnTaskGroup(asAbstract(this));`
`1948`	`1948`	`}`
`1949`	`1949`	`// Put the waiting task at the beginning of the wait queue.`
`1950`		`- if (waitQueue.compare_exchange_strong(`
	`1950`	`+ if (waitQueue.compare_exchange_weak(`
`1951`	`1951`	`waitHead, waitingTask,`
`1952`	`1952`	`/success/ std::memory_order_release,`
`1953`	`1953`	`/failure/ std::memory_order_acquire)) {`