!11577 Use ThreadPool in ParallelFor

From: @wuxuejian
Reviewed-by: @kisnwang,@guoqi1024,@c_34
Signed-off-by: @c_34

mindspore/ccsrc/backend/kernel_compiler/cpu/cpu_kernel.cc

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 #include "backend/kernel_compiler/cpu/cpu_kernel.h"
+#include "common/thread_pool.h"
 
 namespace mindspore {
 namespace kernel {
@@ -81,21 +82,22 @@ void CPUKernelUtils::GetElementNumEveryDim(const std::vector<size_t> &shape, std
 }
 
 void CPUKernelUtils::ParallelFor(const CTask &task, size_t count) {
-  auto max_thread_num = std::thread::hardware_concurrency();
+  auto max_thread_num = common::ThreadPool::GetInstance().GetSyncRunThreadNum();
   const float block_size = 128.0;
   size_t thread_num = count < block_size * max_thread_num ? std::ceil(count / block_size) : max_thread_num;
-  std::vector<std::thread> threads;
-  threads.reserve(thread_num);
+  std::vector<common::Task> tasks;
   size_t start = 0;
   size_t once_compute_size = (count + thread_num - 1) / thread_num;
   while (start < count) {
     size_t end = (start + once_compute_size) > count ? count : (start + once_compute_size);
-    threads.emplace_back(std::thread(task, start, end));
+    auto block = [&, start, end]() {
+      task(start, end);
+      return common::SUCCESS;
+    };
+    tasks.emplace_back(block);
     start += once_compute_size;
   }
-  for (size_t i = 0; i < threads.size(); ++i) {
-    threads[i].join();
-  }
+  common::ThreadPool::GetInstance().SyncRun(tasks);
 }
 
 std::vector<size_t> CPUKernelUtils::FlatShapeByAxis(const std::vector<size_t> &shape, int axis) {