[Cherry-pick] inference modification for custom operator (#31283) (#31300)

Author: Shixiaowei02

paddle/fluid/framework/custom_operator.cc

@@ -667,10 +667,6 @@ void RegisterOperatorWithMetaInfo(
 void RegisterOperatorWithMetaInfoMap(
     const paddle::OpMetaInfoMap& op_meta_info_map) {
   auto& meta_info_map = op_meta_info_map.GetMap();
-
-  PADDLE_ENFORCE_EQ(meta_info_map.empty(), false,
-                    platform::errors::PreconditionNotMet(
-                        "No custom operator that needs to be registered."));
   VLOG(1) << "Custom Operator: size of op meta info map - "
           << meta_info_map.size();
   // pair: {op_type, OpMetaInfo}

paddle/fluid/inference/api/analysis_predictor.cc

@@ -21,6 +21,7 @@
 #include <string>
 #include <utility>
 #include <vector>
+#include "paddle/fluid/extension/include/ext_op_meta_info.h"
 #include "paddle/fluid/framework/feed_fetch_method.h"
 #include "paddle/fluid/framework/feed_fetch_type.h"
 #include "paddle/fluid/framework/ir/fuse_pass_base.h"
@@ -612,6 +613,12 @@ std::unique_ptr<PaddlePredictor> CreatePaddlePredictor<
       platform::errors::InvalidArgument(
           "Note: Each config can only be used for one predictor."));
 
+  // Register custom operators compiled by the user.
+  // This function can only be executed once per process.
+  static std::once_flag custom_operators_registered;
+  std::call_once(custom_operators_registered,
+                 []() { paddle::RegisterAllCustomOperator(); });
+
   if (config.use_gpu()) {
     static std::once_flag gflags_initialized;
     static bool process_level_allocator_enabled;