[SYCL] Relax the mutex lock duration during piQueueFinish

sycl/plugins/level_zero/pi_level_zero.cpp

@@ -3155,19 +3155,28 @@ pi_result piQueueFinish(pi_queue Queue) {
   // Wait until command lists attached to the command queue are executed.
   PI_ASSERT(Queue, PI_INVALID_QUEUE);
 
-  // Lock automatically releases when this goes out of scope.
-  std::lock_guard<std::mutex> lock(Queue->PiQueueMutex);
+  std::vector<ze_command_queue_handle_t> ZeQueues;
+  {
+    // Lock automatically releases when this goes out of scope.
+    std::lock_guard<std::mutex> lock(Queue->PiQueueMutex);
 
-  // execute any command list that may still be open.
-  if (auto Res = Queue->executeAllOpenCommandLists())
-    return Res;
+    // execute any command list that may still be open.
+    if (auto Res = Queue->executeAllOpenCommandLists())
+      return Res;
 
-  ZE_CALL(zeHostSynchronize, (Queue->ZeComputeCommandQueue));
-  for (uint32_t i = 0; i < Queue->ZeCopyCommandQueues.size(); ++i) {
-    if (Queue->ZeCopyCommandQueues[i])
-      ZE_CALL(zeHostSynchronize, (Queue->ZeCopyCommandQueues[i]));
+    ZeQueues = Queue->ZeCopyCommandQueues;
+    ZeQueues.push_back(Queue->ZeComputeCommandQueue);
   }
 
+  // Don't hold a lock to the queue's mutex while waiting.
+  // This allows continue working with the queue from other threads.
+  for (auto ZeQueue : ZeQueues) {
+    if (ZeQueue)
+      ZE_CALL(zeHostSynchronize, (ZeQueue));
+  }
+
+  // Lock automatically releases when this goes out of scope.
+  std::lock_guard<std::mutex> lock(Queue->PiQueueMutex);
   // Prevent unneeded already finished events to show up in the wait list.
   Queue->LastCommandEvent = nullptr;