diff --git a/src/sled/system/thread_pool.cc b/src/sled/system/thread_pool.cc
index 3c54427..e77612a 100644
--- a/src/sled/system/thread_pool.cc
+++ b/src/sled/system/thread_pool.cc
@@ -13,7 +13,7 @@ ThreadPool::ThreadPool(int num_threads) : delayed_thread_(sled::Thread::Create()
     auto state = std::make_shared<State>();
     for (int i = 0; i < num_threads; i++) {
         threads_.emplace_back(std::thread([state] {
-            state->idle++;
+            state->idle.fetch_add(1, std::memory_order_relaxed);
             while (state->is_running) {
                 std::function<void()> task;
                 sled::Location loc = SLED_FROM_HERE;
@@ -26,10 +26,16 @@ ThreadPool::ThreadPool(int num_threads) : delayed_thread_(sled::Thread::Create()
                         loc  = state->task_queue.front().second;
                         state->task_queue.pop();
                     }
+                    // FIXME: can't exit if task add self, must check <is_running>
+                    if (!state->is_running) {
+                        state->idle.fetch_sub(1, std::memory_order_relaxed);
+                        break;
+                    }
+
                     if (!state->task_queue.empty()) { state->cv.NotifyOne(); }
                 }
                 if (task) {
-                    state->idle--;
+                    state->idle.fetch_sub(1, std::memory_order_release);
                     try {
                         task();
                     } catch (const std::exception &e) {
@@ -37,7 +43,7 @@ ThreadPool::ThreadPool(int num_threads) : delayed_thread_(sled::Thread::Create()
                     } catch (...) {
                         LOGE(kTag, "ThreadPool::ThreadPool() task unknown exception, from={}", loc.ToString());
                     }
-                    state->idle++;
+                    state->idle.fetch_add(1, std::memory_order_relaxed);
                 }
             }
         }));