DeviceAPIManager::Global(): does it follow singleton pattern?

Development
1

Hi all,

It looks like DeviceAPIManager::Global() is mis-implemented. For a singleton pattern, it may ought to be implemented as follows:

index d042cb406..772f18ebe 100644
--- a/src/runtime/c_runtime_api.cc
+++ b/src/runtime/c_runtime_api.cc
@@ -35,6 +35,7 @@
 #include <cstdlib>
 #include <sstream>
 #include <string>
+#include <mutex>

 #include "object_internal.h"
 #include "runtime_base.h"
@@ -105,7 +106,12 @@ class DeviceAPIManager {
   DeviceAPIManager() { std::fill(api_.begin(), api_.end(), nullptr); }
   // Global static variable.
   static DeviceAPIManager* Global() {
-    static DeviceAPIManager* inst = new DeviceAPIManager();
+    static std::mutex sinst_mutex;
+    static DeviceAPIManager* inst = nullptr;
+
+    std::lock_guard<std::mutex> lock(sinst_mutex);
+    if (!inst)
+      inst = new DeviceAPIManager();
     return inst;
   }
   // Get or initialize API.