diff --git a/.gitignore b/.gitignore
index 8b9f551..70795cb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -48,9 +48,11 @@ src/tests/test_pthread_lock
 src/tests/test_split_string
 src/tests/test_uniq_skiplist
 src/tests/test_server_id_func
+src/tests/test_pipe
 
 # other
 *.swp
+*.swo
 php-fastcommon/.deps
 php-fastcommon/.libs/
 
diff --git a/HISTORY b/HISTORY
index 5b37c9b..29bfed8 100644
--- a/HISTORY
+++ b/HISTORY
@@ -1,5 +1,5 @@
 
-Version 1.44  2020-03-08
+Version 1.44  2020-03-09
   * add test file src/tests/test_pthread_lock.c
   * add uniq_skiplist.[hc]
   * add function split_string_ex
@@ -17,6 +17,7 @@ Version 1.44  2020-03-08
   * char_converter.[hc]: add function fast_char_unescape
   * struct fast_task_info add ctx pointer for libserverframe nio
   * struct thread_data add waiting_queue for Linux eventfd notify
+  * struct fast_task_info add canceled field for complicated thread model
 
 Version 1.43  2019-12-25
   * replace function call system to getExecResult,
diff --git a/src/fast_task_queue.h b/src/fast_task_queue.h
index d98e33f..469be34 100644
--- a/src/fast_task_queue.h
+++ b/src/fast_task_queue.h
@@ -44,7 +44,7 @@ struct nio_thread_data
 	struct ioevent_puller ev_puller;
 	struct fast_timer timer;
 	int pipe_fds[2];   //for notify
-	struct fast_task_info *deleted_list;
+	struct fast_task_info *deleted_list;   //tasks for cleanup
 	ThreadLoopCallback thread_loop_callback;
 	void *arg;   //extra argument pointer
     struct {
@@ -64,6 +64,7 @@ struct fast_task_info
 	int length; //data length
 	int offset; //current offset
     char nio_stage;  //stage for network IO
+    bool canceled;   //if task canceled
 	int64_t req_count; //request count
 	TaskFinishCallback finish_callback;
 	struct nio_thread_data *thread_data;
diff --git a/src/ioevent_loop.c b/src/ioevent_loop.c
index bb0ce40..1081c0c 100644
--- a/src/ioevent_loop.c
+++ b/src/ioevent_loop.c
@@ -77,16 +77,6 @@ static void deal_timeouts(FastTimerEntry *head)
 	}
 }
 
-void iovent_add_to_deleted_list(struct fast_task_info *pTask)
-{
-    if (pTask->thread_data == NULL) {
-        return;
-    }
-
-    pTask->next = pTask->thread_data->deleted_list;
-    pTask->thread_data->deleted_list = pTask;
-}
-
 int ioevent_loop(struct nio_thread_data *pThreadData,
 	IOEventCallback recv_notify_callback, TaskCleanUpCallback
 	clean_up_callback, volatile bool *continue_flag)
@@ -94,7 +84,7 @@ int ioevent_loop(struct nio_thread_data *pThreadData,
 	int result;
 	IOEventEntry ev_notify;
 	FastTimerEntry head;
-	struct fast_task_info *pTask;
+	struct fast_task_info *task;
 	time_t last_check_time;
 	int count;
 
@@ -142,13 +132,13 @@ int ioevent_loop(struct nio_thread_data *pThreadData,
 			count = 0;
 			while (pThreadData->deleted_list != NULL)
 			{
-				pTask = pThreadData->deleted_list;
-				pThreadData->deleted_list = pTask->next;
+				task = pThreadData->deleted_list;
+				pThreadData->deleted_list = task->next;
 
-				clean_up_callback(pTask);
+				clean_up_callback(task);
 				count++;
 			}
-			logDebug("cleanup task count: %d", count);
+			//logInfo("cleanup task count: %d", count);
 		}
 
 		if (g_current_time - last_check_time > 0)
@@ -170,16 +160,16 @@ int ioevent_loop(struct nio_thread_data *pThreadData,
 	return 0;
 }
 
-int ioevent_set(struct fast_task_info *pTask, struct nio_thread_data *pThread,
+int ioevent_set(struct fast_task_info *task, struct nio_thread_data *pThread,
 	int sock, short event, IOEventCallback callback, const int timeout)
 {
 	int result;
 
-	pTask->thread_data = pThread;
-	pTask->event.fd = sock;
-	pTask->event.callback = callback;
+	task->thread_data = pThread;
+	task->event.fd = sock;
+	task->event.callback = callback;
 	if (ioevent_attach(&pThread->ev_puller,
-		sock, event, pTask) < 0)
+		sock, event, task) < 0)
 	{
 		result = errno != 0 ? errno : ENOENT;
 		logError("file: "__FILE__", line: %d, " \
@@ -189,9 +179,9 @@ int ioevent_set(struct fast_task_info *pTask, struct nio_thread_data *pThread,
 		return result;
 	}
 
-	pTask->event.timer.data = pTask;
-	pTask->event.timer.expires = g_current_time + timeout;
-	result = fast_timer_add(&pThread->timer, &pTask->event.timer);
+	task->event.timer.data = task;
+	task->event.timer.expires = g_current_time + timeout;
+	result = fast_timer_add(&pThread->timer, &task->event.timer);
 	if (result != 0)
 	{
 		logError("file: "__FILE__", line: %d, " \
diff --git a/src/ioevent_loop.h b/src/ioevent_loop.h
index d875eec..0eefbc5 100644
--- a/src/ioevent_loop.h
+++ b/src/ioevent_loop.h
@@ -17,7 +17,23 @@ int ioevent_remove(IOEventPoller *ioevent, void *data);
 int ioevent_set(struct fast_task_info *pTask, struct nio_thread_data *pThread,
 	int sock, short event, IOEventCallback callback, const int timeout);
 
-void iovent_add_to_deleted_list(struct fast_task_info *pTask);
+static inline void iovent_add_to_deleted_list(struct fast_task_info *task)
+{
+    if (task->thread_data == NULL)
+    {
+        return;
+    }
+
+    if (task->canceled) {
+        logError("file: "__FILE__", line: %d, "
+                "task %p already canceled", __LINE__, task);
+        return;
+    }
+
+    task->canceled = true;
+    task->next = task->thread_data->deleted_list;
+    task->thread_data->deleted_list = task;
+}
 
 #ifdef __cplusplus
 }