fix cache key in concat oneDNN kernel (#31820)

* fix cache key in concat oneDNN kernel

* key simplified

paddle/fluid/operators/mkldnn/concat_mkldnn_op.cc

@@ -71,6 +71,15 @@ static const std::vector<const Tensor*> ReduceMultiInput(
   return reduced;
 }
 
+static const std::vector<int> GetDimsForKey(
+    const std::vector<const Tensor*>& inputs) {
+  auto dims_key = paddle::framework::vectorize<int>(inputs[0]->dims());
+  for (auto it = std::next(inputs.begin()); it != inputs.end(); ++it) {
+    dims_key.push_back((*it)->dims()[0]);
+  }
+  return dims_key;
+}
+
 template <typename T>
 class ConcatPrimitiveFactory {
  public:
@@ -134,6 +143,8 @@ template <typename T>
 class ConcatMKLDNNOpKernel : public paddle::framework::OpKernel<T> {
  public:
   void Compute(const paddle::framework::ExecutionContext& ctx) const override {
+    // If any of the multiple inputs of concat has an input size of 0, the
+    // actual size of the multi_input will change
     auto multi_input = ReduceMultiInput(ctx.MultiInput<Tensor>("X"));
     EnforceLayouts(multi_input);
     Tensor* output = ctx.Output<Tensor>("Out");
@@ -156,12 +167,9 @@ class ConcatMKLDNNOpKernel : public paddle::framework::OpKernel<T> {
         paddle::framework::ToMKLDNNDataType(multi_input[0]->type());
 
     ConcatPrimitiveFactory<T> prim_creator;
-    // If one of the multiple inputs of concat has an input size of 0, the
-    // actual size of the multi_input will change
-    std::string key = platform::CreateKey(
-        dev_ctx, paddle::framework::vectorize<int>(multi_input[0]->dims()),
-        multi_input.size(), ctx.OutputName("Out"), dt,
-        platform::ThreadIDasStr());
+    std::string key =
+        platform::CreateKey(dev_ctx, GetDimsForKey(multi_input),
+                            multi_input.size(), ctx.OutputName("Out"), dt);
     key = platform::ExtendKeyWithThreadInfoIfNeeded(dev_ctx, key);
 
     const std::string key_prim = key + "@concat_p";