detect grpc fork support

src/Environment/Fork/ForkWorker.php

@@ -18,6 +18,26 @@
  */
 class ForkWorker extends SocketWorker
 {
+    /**
+     * @return bool
+     */
+    public static function isSupported(): bool
+    {
+        if (!extension_loaded("pcntl")) {
+            return false;
+        }
+
+        // GRPC only supports forks if explicitly enabled using the GRPC_ENABLE_FORK_SUPPORT environment variable
+        // see https://github.com/grpc/grpc/issues/13412
+        // If you don't use GRPC, but have the extension loaded, you can always define your workers manually
+        // or override the automatic worker selection using the TASKMASTER_WORKER environment variable
+        if (extension_loaded("grpc") && getenv("GRPC_ENABLE_FORK_SUPPORT") !== "1") {
+            return false;
+        }
+
+        return true;
+    }
+
     /**
      * @return WorkerInstanceInterface
      */

src/Environment/Process/ProcessWorker.php

@@ -16,6 +16,14 @@
  */
 class ProcessWorker extends SocketWorker
 {
+    /**
+     * @return bool
+     */
+    public static function isSupported(): bool
+    {
+        return function_exists("proc_open") && PHP_OS_FAMILY !== "Windows";
+    }
+
     /**
      * @return ProcessWorkerInstance
      */

src/Taskmaster.php

@@ -340,7 +340,6 @@ protected function getSelectableStreams(): array
      *
      * @param SocketInterface|null $socket
      * @return resource|null
-     * @noinspection PhpMixedReturnTypeCanBeReducedInspection
      */
     protected function getSelectableReadStreamFromSocket(?SocketInterface $socket): mixed
     {
@@ -463,9 +462,9 @@ public function autoDetectWorkers(int $count, bool $loadFromEnv = true, bool $al
         }
 
         if (!$worker) {
-            if (extension_loaded("pcntl")) {
+            if (ForkWorker::isSupported()) {
                 $worker = new ForkWorker();
-            } elseif (function_exists("proc_open") && PHP_OS_FAMILY !== "Windows") {
+            } elseif (ProcessWorker::isSupported()) {
                 $worker = new ProcessWorker();
             } else {
                 $worker = new SyncWorker();