fix: race condition revealed by tests (#1403)

* Resolves a race condition

* Removes unused code.

* trigger build

* Removes accidental files.

---------

Co-authored-by: Alliballibaba <alliballibaba@gmail.com>

Author: AlliBalliBaba

scaling.go

@@ -74,18 +74,6 @@ func addRegularThread() (*phpThread, error) {
 	return thread, nil
 }
 
-func removeRegularThread() error {
-	regularThreadMu.RLock()
-	if len(regularThreads) <= 1 {
-		regularThreadMu.RUnlock()
-		return CannotRemoveLastThreadError
-	}
-	thread := regularThreads[len(regularThreads)-1]
-	regularThreadMu.RUnlock()
-	thread.shutdown()
-	return nil
-}
-
 func addWorkerThread(worker *worker) (*phpThread, error) {
 	thread := getInactivePHPThread()
 	if thread == nil {
@@ -96,19 +84,6 @@ func addWorkerThread(worker *worker) (*phpThread, error) {
 	return thread, nil
 }
 
-func removeWorkerThread(worker *worker) error {
-	worker.threadMutex.RLock()
-	if len(worker.threads) <= 1 {
-		worker.threadMutex.RUnlock()
-		return CannotRemoveLastThreadError
-	}
-	thread := worker.threads[len(worker.threads)-1]
-	worker.threadMutex.RUnlock()
-	thread.shutdown()
-
-	return nil
-}
-
 // scaleWorkerThread adds a worker PHP thread automatically
 func scaleWorkerThread(worker *worker) {
 	scalingMu.Lock()

threadworker.go

@@ -150,8 +150,10 @@ func (handler *workerThread) waitForWorkerRequest() bool {
 		c.Write(zap.String("worker", handler.worker.fileName))
 	}
 
-	if handler.state.compareAndSwap(stateTransitionComplete, stateReady) {
+	// worker threads are 'ready' only after they first reach frankenphp_handle_request()
+	if handler.state.is(stateTransitionComplete) {
 		metrics.ReadyWorker(handler.worker.fileName)
+		handler.state.set(stateReady)
 	}
 
 	handler.state.markAsWaiting(true)