fix

taichi/program/program.h

@@ -6,6 +6,7 @@
 #include <optional>
 #include <atomic>
 #include <stack>
+#include <shared_mutex>
 
 #define TI_RUNTIME_HOST
 #include "taichi/aot/module_builder.h"
@@ -125,9 +126,12 @@ class TI_DLL_EXPORT Program {
 
   CompileConfig &this_thread_config() {
     auto thread_id = std::this_thread::get_id();
+    std::shared_lock<std::shared_mutex> sharedLock(compile_config_mut);
     if (!configs.count(thread_id)) {
-      std::lock_guard<std::mutex> _(compile_config_mut);
+      sharedLock.unlock();
+      std::unique_lock<std::shared_mutex> uniqueLock(compile_config_mut);
       configs[thread_id] = configs[main_thread_id_];
+      return configs[thread_id];
     }
     return configs[thread_id];
   }
@@ -397,7 +401,7 @@ class TI_DLL_EXPORT Program {
   std::vector<std::unique_ptr<Ndarray>> ndarrays_;
   std::vector<std::unique_ptr<Texture>> textures_;
 
-  std::mutex compile_config_mut;
+  std::shared_mutex compile_config_mut;
 };
 
 }  // namespace taichi::lang