[SYCL] Lock mutex only for critical region in interop-level-zero-thread.cpp (intel#1418)

Author: raaiq1

SYCL/Plugin/interop-level-zero-thread.cpp

@@ -110,15 +110,19 @@ ze_event_handle_t getEvent() {
 }
 
 void worker() {
-  std::unique_lock<std::mutex> lk(mt);
-
   while (true) {
-    cv.wait(lk, []() { return ops.size() > 0 || stop_worker; });
-    if (stop_worker)
-      return;
-    auto op = ops.front();
-    ops.pop_front();
 
+    operation op;
+    {
+
+      std::unique_lock<std::mutex> lk(mt);
+      cv.wait(lk, []() { return ops.size() > 0 || stop_worker; });
+      if (stop_worker)
+        return;
+
+      op = ops.front();
+      ops.pop_front();
+    }
     for (auto dep : op.deps) {
       // Wait for dependencies to complete
       while (dep.get_info<sycl::info::event::command_execution_status>() !=