diff --git a/HISTORY b/HISTORY
index 77590d2..66015e4 100644
--- a/HISTORY
+++ b/HISTORY
@@ -1,11 +1,12 @@
 
-Version 1.70  2023-09-20
+Version 1.70  2023-09-25
   * get full mac address of infiniband NIC under Linux
   * struct fast_task_info add field conn for RDMA connection
   * server_id_func.[hc]: support communication type
   * connection_pool.[hc] support callbacks for RDMA 
   * nio thread data support busy_polling_callback
   * connection_pool.[hc] support thread local for performance
+  * struct fast_task_info support send and recv double buffers
 
 Version 1.69  2023-08-05
   * bugfixed: array_allocator_alloc MUST init the array
diff --git a/src/fast_task_queue.c b/src/fast_task_queue.c
index 1757cd2..a0550c3 100644
--- a/src/fast_task_queue.c
+++ b/src/fast_task_queue.c
@@ -25,656 +25,183 @@
 #include "fc_memory.h"
 #include "fast_task_queue.h"
 
-static struct fast_task_queue g_free_queue;
-
-struct mpool_node {
-	struct fast_task_info *blocks;
-	struct fast_task_info *last_block;   //last block
-	struct mpool_node *next;
-};
-
-struct mpool_chain {
-    struct mpool_node *head;
-    struct mpool_node *tail;
-};
-
-static struct mpool_chain g_mpool = {NULL, NULL};
-
-int task_queue_init(struct fast_task_queue *pQueue)
+static int task_alloc_init(struct fast_task_info *task,
+        struct fast_task_queue *queue)
 {
-	int result;
-
-	if ((result=init_pthread_lock(&(pQueue->lock))) != 0)
-	{
-		logError("file: "__FILE__", line: %d, " \
-			"init_pthread_lock fail, errno: %d, error info: %s", \
-			__LINE__, result, STRERROR(result));
-		return result;
-	}
-
-	pQueue->head = NULL;
-	pQueue->tail = NULL;
-
-	return 0;
-}
-
-static void free_mpool(struct mpool_node *mpool, char *end)
-{
-    char *pt;
-    for (pt=(char *)mpool->blocks; pt < end; pt += g_free_queue.block_size)
-    {
-        free(((struct fast_task_info *)pt)->data);
+    task->arg = (char *)task + ALIGNED_TASK_INFO_SIZE + queue->padding_size;
+    task->send.ptr = &task->send.holder;
+    task->send.ptr->size = queue->min_buff_size;
+    if (queue->malloc_whole_block) {
+        task->send.ptr->data = (char *)task->arg + queue->arg_size;
+    } else {
+        task->send.ptr->data = (char *)fc_malloc(task->send.ptr->size);
+        if (task->send.ptr->data == NULL) {
+            return ENOMEM;
+        }
     }
 
-    free(mpool->blocks);
-    free(mpool);
-}
-
-static struct mpool_node *malloc_mpool(const int total_alloc_size)
-{
-	struct fast_task_info *pTask;
-	char *p;
-	char *pCharEnd;
-	struct mpool_node *mpool;
-
-	mpool = (struct mpool_node *)fc_malloc(sizeof(struct mpool_node));
-	if (mpool == NULL)
-	{
-		return NULL;
-	}
-
-	mpool->next = NULL;
-	mpool->blocks = (struct fast_task_info *)fc_malloc(total_alloc_size);
-	if (mpool->blocks == NULL)
-	{
-		free(mpool);
-		return NULL;
-	}
-	memset(mpool->blocks, 0, total_alloc_size);
-
-	pCharEnd = ((char *)mpool->blocks) + total_alloc_size;
-	for (p=(char *)mpool->blocks; p<pCharEnd; p += g_free_queue.block_size)
-	{
-		pTask = (struct fast_task_info *)p;
-		pTask->size = g_free_queue.min_buff_size;
-
-		pTask->arg = p + ALIGNED_TASK_INFO_SIZE + g_free_queue.padding_size;
-		if (g_free_queue.malloc_whole_block)
-		{
-			pTask->data = (char *)pTask->arg + g_free_queue.arg_size;
-		}
-		else
-		{
-			pTask->data = (char *)fc_malloc(pTask->size);
-			if (pTask->data == NULL)
-			{
-                free_mpool(mpool, p);
-				return NULL;
-			}
-		}
-
-        if (g_free_queue.init_callback != NULL)
-        {
-            if (g_free_queue.init_callback(pTask) != 0)
-            {
-                free_mpool(mpool, p);
-                return NULL;
-            }
+    if (queue->double_buffers) {
+        task->recv.ptr = &task->recv.holder;
+        task->recv.ptr->size = queue->min_buff_size;
+        task->recv.ptr->data = (char *)fc_malloc(task->recv.ptr->size);
+        if (task->recv.ptr->data == NULL) {
+            return ENOMEM;
         }
-	}
+    } else {
+        task->recv.ptr = &task->send.holder;
+    }
 
-	mpool->last_block = (struct fast_task_info *)
-        (pCharEnd - g_free_queue.block_size);
-	for (p=(char *)mpool->blocks; p<(char *)mpool->last_block;
-            p += g_free_queue.block_size)
-	{
-		pTask = (struct fast_task_info *)p;
-		pTask->next = (struct fast_task_info *)(p + g_free_queue.block_size);
-	}
-	mpool->last_block->next = NULL;
-
-	return mpool;
+    task->free_queue = queue;
+    if (queue->init_callback != NULL) {
+        return queue->init_callback(task);
+    }
+    return 0;
 }
 
-int free_queue_init_ex2(const int max_connections, const int init_connections,
+int free_queue_init_ex2(struct fast_task_queue *queue, const char *name,
+        const bool double_buffers, const int max_connections,
         const int alloc_task_once, const int min_buff_size,
         const int max_buff_size, const int padding_size,
         const int arg_size, TaskInitCallback init_callback)
 {
 #define MAX_DATA_SIZE  (256 * 1024 * 1024)
-	int64_t total_size;
-	struct mpool_node *mpool;
-	int alloc_size;
     int alloc_once;
-	int result;
-	int loop_count;
 	int aligned_min_size;
 	int aligned_max_size;
 	int aligned_padding_size;
 	int aligned_arg_size;
 	rlim_t max_data_size;
-
-	if ((result=init_pthread_lock(&(g_free_queue.lock))) != 0)
-	{
-		logError("file: "__FILE__", line: %d, "
-			"init_pthread_lock fail, errno: %d, error info: %s",
-			__LINE__, result, STRERROR(result));
-		return result;
-	}
+    char aname[64];
 
 	aligned_min_size = MEM_ALIGN(min_buff_size);
 	aligned_max_size = MEM_ALIGN(max_buff_size);
     aligned_padding_size = MEM_ALIGN(padding_size);
 	aligned_arg_size = MEM_ALIGN(arg_size);
-	g_free_queue.block_size = ALIGNED_TASK_INFO_SIZE +
+	queue->block_size = ALIGNED_TASK_INFO_SIZE +
         aligned_padding_size + aligned_arg_size;
-	alloc_size = g_free_queue.block_size * init_connections;
-	if (aligned_max_size > aligned_min_size)
-	{
-		total_size = alloc_size;
-		g_free_queue.malloc_whole_block = false;
+    if (alloc_task_once <= 0) {
+        alloc_once = FC_MIN(MAX_DATA_SIZE / queue->block_size, 256);
+        if (alloc_once == 0) {
+            alloc_once = 1;
+        }
+    } else {
+        alloc_once = alloc_task_once;
+    }
+
+	if (aligned_max_size > aligned_min_size) {
+		queue->malloc_whole_block = false;
 		max_data_size = 0;
-	}
-	else
-	{
-		struct rlimit rlimit_data;
+    } else {
+        struct rlimit rlimit_data;
 
-		if (getrlimit(RLIMIT_DATA, &rlimit_data) < 0)
-		{
-			logError("file: "__FILE__", line: %d, "
-				"call getrlimit fail, "
-				"errno: %d, error info: %s",
-				__LINE__, errno, STRERROR(errno));
-			return errno != 0 ? errno : EPERM;
-		}
-		if (rlimit_data.rlim_cur == RLIM_INFINITY)
-		{
-			max_data_size = MAX_DATA_SIZE;
-		}
-		else
-		{
-			max_data_size = rlimit_data.rlim_cur;
-			if (max_data_size > MAX_DATA_SIZE)
-			{
-				max_data_size = MAX_DATA_SIZE;
-			}
-		}
+        if (getrlimit(RLIMIT_DATA, &rlimit_data) < 0) {
+            logError("file: "__FILE__", line: %d, "
+                    "call getrlimit fail, "
+                    "errno: %d, error info: %s",
+                    __LINE__, errno, STRERROR(errno));
+            return errno != 0 ? errno : EPERM;
+        }
+        if (rlimit_data.rlim_cur == RLIM_INFINITY) {
+            max_data_size = MAX_DATA_SIZE;
+        } else {
+            max_data_size = rlimit_data.rlim_cur;
+            if (max_data_size > MAX_DATA_SIZE) {
+                max_data_size = MAX_DATA_SIZE;
+            }
+        }
 
-		if (max_data_size >= (int64_t)(g_free_queue.block_size +
-                    aligned_min_size) * (int64_t)init_connections)
-		{
-			total_size = alloc_size + (int64_t)aligned_min_size *
-					init_connections;
-			g_free_queue.malloc_whole_block = true;
-			g_free_queue.block_size += aligned_min_size;
-		}
-		else
-		{
-			total_size = alloc_size;
-			g_free_queue.malloc_whole_block = false;
-			max_data_size = 0;
-		}
-	}
-
-	g_free_queue.max_connections = max_connections;
-	g_free_queue.alloc_connections = init_connections;
-    if (alloc_task_once <= 0)
-    {
-        g_free_queue.alloc_task_once = 256;
-		alloc_once = MAX_DATA_SIZE / g_free_queue.block_size;
-        if (g_free_queue.alloc_task_once > alloc_once)
+        if (max_data_size >= (int64_t)(queue->block_size +
+                    aligned_min_size) * (int64_t)alloc_once)
         {
-            g_free_queue.alloc_task_once = alloc_once > 0 ? alloc_once : 1;
+            queue->malloc_whole_block = true;
+            queue->block_size += aligned_min_size;
+        } else {
+            queue->malloc_whole_block = false;
+            max_data_size = 0;
         }
     }
-    else
-    {
-        g_free_queue.alloc_task_once = alloc_task_once;
-    }
-	g_free_queue.min_buff_size = aligned_min_size;
-	g_free_queue.max_buff_size = aligned_max_size;
-	g_free_queue.padding_size = aligned_padding_size;
-	g_free_queue.arg_size = aligned_arg_size;
-	g_free_queue.init_callback = init_callback;
 
-	logDebug("file: "__FILE__", line: %d, "
-		"max_connections: %d, init_connections: %d, alloc_task_once: %d, "
+    queue->double_buffers = double_buffers;
+	queue->min_buff_size = aligned_min_size;
+	queue->max_buff_size = aligned_max_size;
+	queue->padding_size = aligned_padding_size;
+	queue->arg_size = aligned_arg_size;
+	queue->init_callback = init_callback;
+
+    /*
+	logInfo("file: "__FILE__", line: %d, [%s] double_buffers: %d, "
+		"max_connections: %d, alloc_once: %d, malloc_whole_block: %d, "
         "min_buff_size: %d, max_buff_size: %d, block_size: %d, "
-        "padding_size: %d, arg_size: %d, max_data_size: %"PRId64", "
-        "total_size: %"PRId64, __LINE__, max_connections, init_connections,
-        g_free_queue.alloc_task_once, aligned_min_size, aligned_max_size,
-        g_free_queue.block_size, aligned_padding_size, aligned_arg_size,
-        (int64_t)max_data_size, total_size);
+        "padding_size: %d, arg_size: %d, max_data_size: %"PRId64,
+        __LINE__, name, double_buffers, max_connections, alloc_once,
+        queue->malloc_whole_block, aligned_min_size, aligned_max_size,
+        queue->block_size, aligned_padding_size, aligned_arg_size,
+        (int64_t)max_data_size);
+        */
 
-	if ((!g_free_queue.malloc_whole_block) || (total_size <= max_data_size))
-	{
-		loop_count = 1;
-		mpool = malloc_mpool(total_size);
-		if (mpool == NULL)
-		{
-			return errno != 0 ? errno : ENOMEM;
-		}
-		g_mpool.head = mpool;
-		g_mpool.tail = mpool;
-	}
-	else
-	{
-		int remain_count;
-		int alloc_count;
-		int current_alloc_size;
-
-		loop_count = 0;
-		remain_count = init_connections;
-		alloc_once = max_data_size / g_free_queue.block_size;
-		while (remain_count > 0)
-		{
-			alloc_count = (remain_count > alloc_once) ?
-					alloc_once : remain_count;
-			current_alloc_size = g_free_queue.block_size * alloc_count;
-			mpool = malloc_mpool(current_alloc_size);
-			if (mpool == NULL)
-			{
-				free_queue_destroy();
-				return errno != 0 ? errno : ENOMEM;
-			}
-
-			if (g_mpool.tail == NULL)
-			{
-				g_mpool.head = mpool;
-			}
-			else
-			{
-				g_mpool.tail->next = mpool;
-				g_mpool.tail->last_block->next = mpool->blocks;  //link previous mpool to current
-			}
-            g_mpool.tail = mpool;
-
-			remain_count -= alloc_count;
-			loop_count++;
-		}
-
-		logDebug("file: "__FILE__", line: %d, " \
-			"alloc_once: %d", __LINE__, alloc_once);
-	}
-
-	logDebug("file: "__FILE__", line: %d, " \
-		"malloc task info as whole: %d, malloc loop count: %d", \
-		__LINE__, g_free_queue.malloc_whole_block, loop_count);
-
-	if (g_mpool.head != NULL)
-	{
-		g_free_queue.head = g_mpool.head->blocks;
-		g_free_queue.tail = g_mpool.tail->last_block;
-	}
-
-	return 0;
+    snprintf(aname, sizeof(aname), "%s-task", name);
+	return fast_mblock_init_ex1(&queue->allocator, aname,
+            queue->block_size, alloc_once, max_connections,
+            (fast_mblock_object_init_func)task_alloc_init,
+            queue, true);
 }
 
-void free_queue_destroy()
+void free_queue_destroy(struct fast_task_queue *queue)
 {
-	struct mpool_node *mpool;
-	struct mpool_node *mp;
-
-	if (g_mpool.head == NULL)
-	{
-		return;
-	}
-
-	if (!g_free_queue.malloc_whole_block)
-	{
-		char *p;
-		char *pCharEnd;
-		struct fast_task_info *pTask;
-
-        mpool = g_mpool.head;
-        while (mpool != NULL)
-        {
-            pCharEnd = (char *)mpool->last_block + g_free_queue.block_size;
-            for (p=(char *)mpool->blocks; p<pCharEnd; p += g_free_queue.block_size)
-            {
-                pTask = (struct fast_task_info *)p;
-                if (pTask->data != NULL)
-                {
-                    free(pTask->data);
-                    pTask->data = NULL;
-                }
-            }
-            mpool = mpool->next;
-        }
-	}
-
-	mpool = g_mpool.head;
-	while (mpool != NULL)
-	{
-		mp = mpool;
-		mpool = mpool->next;
-
-		free(mp->blocks);
-		free(mp);
-	}
-	g_mpool.head = g_mpool.tail = NULL;
-
-	pthread_mutex_destroy(&(g_free_queue.lock));
+    fast_mblock_destroy(&queue->allocator);
 }
 
-static int free_queue_realloc()
-{
-	struct mpool_node *mpool;
-	struct fast_task_info *head;
-	struct fast_task_info *tail;
-	int remain_count;
-	int alloc_count;
-	int current_alloc_size;
-
-    head = tail = NULL;
-	remain_count = g_free_queue.max_connections -
-        g_free_queue.alloc_connections;
-    alloc_count = (remain_count > g_free_queue.alloc_task_once) ?
-        g_free_queue.alloc_task_once : remain_count;
-    if (alloc_count > 0)
-	{
-		current_alloc_size = g_free_queue.block_size * alloc_count;
-		mpool = malloc_mpool(current_alloc_size);
-		if (mpool == NULL)
-		{
-            return ENOMEM;
-		}
-
-		if (g_mpool.tail == NULL)
-		{
-			g_mpool.head = mpool;
-		}
-		else
-		{
-			g_mpool.tail->next = mpool;
-		}
-        g_mpool.tail = mpool;
-
-        head = mpool->blocks;
-        tail = mpool->last_block;
-
-		remain_count -= alloc_count;
-	}
-    else {
-        return ENOSPC;
-    }
-
-    if (g_free_queue.head == NULL)
-    {
-        g_free_queue.head = head;
-    }
-    if (g_free_queue.tail != NULL)
-    {
-        g_free_queue.tail->next = head;
-    }
-    g_free_queue.tail = tail;
-
-    g_free_queue.alloc_connections += alloc_count;
-
-	logDebug("file: "__FILE__", line: %d, "
-		"alloc_connections: %d, realloc %d elements", __LINE__,
-        g_free_queue.alloc_connections, alloc_count);
-
-    return 0;
-}
-
-struct fast_task_info *free_queue_pop()
-{
-    struct fast_task_info *pTask;
-    int i;
-
-	if ((pTask=task_queue_pop(&g_free_queue)) != NULL)
-    {
-        return pTask;
-    }
-
-    if (g_free_queue.alloc_connections >= g_free_queue.max_connections)
-    {
-        return NULL;
-    }
-
-    for (i=0; i<10; i++)
-    {
-        pthread_mutex_lock(&g_free_queue.lock);
-        if (g_free_queue.alloc_connections >= g_free_queue.max_connections)
-        {
-            if (g_free_queue.head == NULL)
-            {
-                pthread_mutex_unlock(&g_free_queue.lock);
-                return NULL;
-            }
-        }
-        else
-        {
-            if (g_free_queue.head == NULL && free_queue_realloc() != 0)
-            {
-                pthread_mutex_unlock(&g_free_queue.lock);
-                return NULL;
-            }
-        }
-        pthread_mutex_unlock(&g_free_queue.lock);
-
-        if ((pTask=task_queue_pop(&g_free_queue)) != NULL)
-        {
-            return pTask;
-        }
-    }
-
-    return NULL;
-}
-
-static int _realloc_buffer(struct fast_task_info *pTask, const int new_size,
-        const bool copy_data)
+static int _realloc_buffer(struct fast_net_buffer *buffer,
+        const int new_size, const bool copy_data)
 {
 	char *new_buff;
 
     new_buff = (char *)fc_malloc(new_size);
-    if (new_buff == NULL)
-    {
+    if (new_buff == NULL) {
         return ENOMEM;
     }
-    else
-    {
-        if (copy_data && pTask->offset > 0) {
-            memcpy(new_buff, pTask->data, pTask->offset);
-        }
-        free(pTask->data);
-        pTask->size = new_size;
-        pTask->data = new_buff;
-        return 0;
+
+    if (copy_data && buffer->offset > 0) {
+        memcpy(new_buff, buffer->data, buffer->offset);
     }
+    free(buffer->data);
+    buffer->size = new_size;
+    buffer->data = new_buff;
+    return 0;
 }
 
-int free_queue_push(struct fast_task_info *pTask)
+void free_queue_push(struct fast_task_info *task)
 {
-	int result;
+    *(task->client_ip) = '\0';
+    task->send.ptr->length = 0;
+    task->send.ptr->offset = 0;
+    task->req_count = 0;
+    if (task->send.ptr->size > task->free_queue->min_buff_size) {//need thrink
+        _realloc_buffer(task->send.ptr, task->free_queue->min_buff_size, false);
+    }
 
-	*(pTask->client_ip) = '\0';
-	pTask->length = 0;
-	pTask->offset = 0;
-	pTask->req_count = 0;
+    if (task->free_queue->double_buffers) {
+        task->recv.ptr->length = 0;
+        task->recv.ptr->offset = 0;
+        if (task->recv.ptr->size > task->free_queue->min_buff_size) {
+            _realloc_buffer(task->recv.ptr, task->free_queue->
+                    min_buff_size, false);
+        }
+    }
 
-	if (pTask->size > g_free_queue.min_buff_size) //need thrink
-	{
-        _realloc_buffer(pTask, g_free_queue.min_buff_size, false);
-	}
-
-	if ((result=pthread_mutex_lock(&g_free_queue.lock)) != 0)
-	{
-		logError("file: "__FILE__", line: %d, " \
-			"call pthread_mutex_lock fail, " \
-			"errno: %d, error info: %s", \
-			__LINE__, result, STRERROR(result));
-	}
-
-	pTask->next = g_free_queue.head;
-	g_free_queue.head = pTask;
-	if (g_free_queue.tail == NULL)
-	{
-		g_free_queue.tail = pTask;
-	}
-
-	if ((result=pthread_mutex_unlock(&g_free_queue.lock)) != 0)
-	{
-		logError("file: "__FILE__", line: %d, " \
-			"call pthread_mutex_unlock fail, " \
-			"errno: %d, error info: %s", \
-			__LINE__, result, STRERROR(result));
-	}
-
-	return result;
+    fast_mblock_free_object(&task->free_queue->allocator, task);
 }
 
-int free_queue_count()
-{
-	return task_queue_count(&g_free_queue);
-}
-
-int free_queue_alloc_connections()
-{
-    return g_free_queue.alloc_connections;
-}
-
-int free_queue_set_buffer_size(struct fast_task_info *pTask,
-        const int expect_size)
-{
-    return task_queue_set_buffer_size(&g_free_queue, pTask, expect_size);
-}
-
-int free_queue_realloc_buffer(struct fast_task_info *pTask,
-        const int expect_size)
-{
-    return task_queue_realloc_buffer(&g_free_queue, pTask, expect_size);
-}
-
-int free_queue_set_max_buffer_size(struct fast_task_info *pTask)
-{
-    return task_queue_set_buffer_size(&g_free_queue, pTask,
-            g_free_queue.max_buff_size);
-}
-
-int free_queue_realloc_max_buffer(struct fast_task_info *pTask)
-{
-    return task_queue_realloc_buffer(&g_free_queue, pTask,
-            g_free_queue.max_buff_size);
-}
-int task_queue_push(struct fast_task_queue *pQueue, \
-		struct fast_task_info *pTask)
-{
-	int result;
-
-	if ((result=pthread_mutex_lock(&(pQueue->lock))) != 0)
-	{
-		logError("file: "__FILE__", line: %d, " \
-			"call pthread_mutex_lock fail, " \
-			"errno: %d, error info: %s", \
-			__LINE__, result, STRERROR(result));
-		return result;
-	}
-
-	pTask->next = NULL;
-	if (pQueue->tail == NULL)
-	{
-		pQueue->head = pTask;
-	}
-	else
-	{
-		pQueue->tail->next = pTask;
-	}
-	pQueue->tail = pTask;
-
-	if ((result=pthread_mutex_unlock(&(pQueue->lock))) != 0)
-	{
-		logError("file: "__FILE__", line: %d, " \
-			"call pthread_mutex_unlock fail, " \
-			"errno: %d, error info: %s", \
-			__LINE__, result, STRERROR(result));
-	}
-
-	return 0;
-}
-
-struct fast_task_info *task_queue_pop(struct fast_task_queue *pQueue)
-{
-	struct fast_task_info *pTask;
-	int result;
-
-	if ((result=pthread_mutex_lock(&(pQueue->lock))) != 0)
-	{
-		logError("file: "__FILE__", line: %d, " \
-			"call pthread_mutex_lock fail, " \
-			"errno: %d, error info: %s", \
-			__LINE__, result, STRERROR(result));
-		return NULL;
-	}
-
-	pTask = pQueue->head;
-	if (pTask != NULL)
-	{
-		pQueue->head = pTask->next;
-		if (pQueue->head == NULL)
-		{
-			pQueue->tail = NULL;
-		}
-	}
-
-	if ((result=pthread_mutex_unlock(&(pQueue->lock))) != 0)
-	{
-		logError("file: "__FILE__", line: %d, " \
-			"call pthread_mutex_unlock fail, " \
-			"errno: %d, error info: %s", \
-			__LINE__, result, STRERROR(result));
-	}
-
-	return pTask;
-}
-
-int task_queue_count(struct fast_task_queue *pQueue)
-{
-	struct fast_task_info *pTask;
-	int count;
-	int result;
-
-	if ((result=pthread_mutex_lock(&(pQueue->lock))) != 0)
-	{
-		logError("file: "__FILE__", line: %d, " \
-			"call pthread_mutex_lock fail, " \
-			"errno: %d, error info: %s", \
-			__LINE__, result, STRERROR(result));
-		return 0;
-	}
-
-	count = 0;
-	pTask = pQueue->head;
-	while (pTask != NULL)
-	{
-		pTask = pTask->next;
-		count++;
-	}
-
-	if ((result=pthread_mutex_unlock(&(pQueue->lock))) != 0)
-	{
-		logError("file: "__FILE__", line: %d, " \
-			"call pthread_mutex_unlock fail, " \
-			"errno: %d, error info: %s", \
-			__LINE__, result, STRERROR(result));
-	}
-
-	return count;
-}
-
-int task_queue_get_new_buffer_size(const int min_buff_size,
+int free_queue_get_new_buffer_size(const int min_buff_size,
         const int max_buff_size, const int expect_size, int *new_size)
 {
-    if (min_buff_size == max_buff_size)
-    {
+    if (min_buff_size == max_buff_size) {
         logError("file: "__FILE__", line: %d, "
                 "can't change buffer size because NOT supported", __LINE__);
         return EOPNOTSUPP;
     }
 
-    if (expect_size > max_buff_size)
-    {
+    if (expect_size > max_buff_size) {
         logError("file: "__FILE__", line: %d, "
                 "can't change buffer size because expect buffer size: %d "
                 "exceeds max buffer size: %d", __LINE__, expect_size,
@@ -683,14 +210,11 @@ int task_queue_get_new_buffer_size(const int min_buff_size,
     }
 
     *new_size = min_buff_size;
-    if (expect_size > min_buff_size)
-    {
-        while (*new_size < expect_size)
-        {
+    if (expect_size > min_buff_size) {
+        while (*new_size < expect_size) {
             *new_size *= 2;
         }
-        if (*new_size > max_buff_size)
-        {
+        if (*new_size > max_buff_size) {
             *new_size = max_buff_size;
         }
     }
@@ -698,41 +222,43 @@ int task_queue_get_new_buffer_size(const int min_buff_size,
     return 0;
 }
 
-#define  _get_new_buffer_size(pQueue, expect_size, new_size) \
-    task_queue_get_new_buffer_size(pQueue->min_buff_size, \
-            pQueue->max_buff_size, expect_size, new_size)
+#define  _get_new_buffer_size(queue, expect_size, new_size) \
+    free_queue_get_new_buffer_size(queue->min_buff_size, \
+            queue->max_buff_size, expect_size, new_size)
 
-int task_queue_set_buffer_size(struct fast_task_queue *pQueue,
-        struct fast_task_info *pTask, const int expect_size)
+int free_queue_set_buffer_size(struct fast_task_info *task,
+        struct fast_net_buffer *buffer, const int expect_size)
 {
     int result;
     int new_size;
 
-    if ((result=_get_new_buffer_size(pQueue, expect_size, &new_size)) != 0) {
+    if ((result=_get_new_buffer_size(task->free_queue,
+                    expect_size, &new_size)) != 0)
+    {
         return result;
     }
-    if (pTask->size == new_size)  //do NOT need change buffer size
-    {
+    if (buffer->size == new_size) { //do NOT need change buffer size
         return 0;
     }
 
-    return _realloc_buffer(pTask, new_size, false);
+    return _realloc_buffer(buffer, new_size, false);
 }
 
-int task_queue_realloc_buffer(struct fast_task_queue *pQueue,
-        struct fast_task_info *pTask, const int expect_size)
+int free_queue_realloc_buffer(struct fast_task_info *task,
+        struct fast_net_buffer *buffer, const int expect_size)
 {
     int result;
     int new_size;
 
-    if (pTask->size >= expect_size)  //do NOT need change buffer size
-    {
+    if (buffer->size >= expect_size) {  //do NOT need change buffer size
         return 0;
     }
 
-    if ((result=_get_new_buffer_size(pQueue, expect_size, &new_size)) != 0) {
+    if ((result=_get_new_buffer_size(task->free_queue,
+                    expect_size, &new_size)) != 0)
+    {
         return result;
     }
 
-    return _realloc_buffer(pTask, new_size, true);
+    return _realloc_buffer(buffer, new_size, true);
 }
diff --git a/src/fast_task_queue.h b/src/fast_task_queue.h
index 1f58f62..b5ef4f8 100644
--- a/src/fast_task_queue.h
+++ b/src/fast_task_queue.h
@@ -23,9 +23,10 @@
 #include <string.h>
 #include <pthread.h>
 #include "common_define.h"
+#include "fc_list.h"
 #include "ioevent.h"
 #include "fast_timer.h"
-#include "fc_list.h"
+#include "fast_mblock.h"
 
 #define FC_NOTIFY_READ_FD(tdata)  (tdata)->pipe_fds[0]
 #define FC_NOTIFY_WRITE_FD(tdata) (tdata)->pipe_fds[1]
@@ -36,9 +37,9 @@ struct nio_thread_data;
 struct fast_task_info;
 
 typedef int (*ThreadLoopCallback) (struct nio_thread_data *pThreadData);
-typedef int (*TaskFinishCallback) (struct fast_task_info *pTask);
-typedef void (*TaskCleanUpCallback) (struct fast_task_info *pTask);
-typedef int (*TaskInitCallback)(struct fast_task_info *pTask);
+typedef int (*TaskFinishCallback) (struct fast_task_info *task);
+typedef void (*TaskCleanUpCallback) (struct fast_task_info *task);
+typedef int (*TaskInitCallback)(struct fast_task_info *task);
 
 typedef void (*IOEventCallback) (int sock, short event, void *arg);
 typedef int (*TaskContinueCallback)(struct fast_task_info *task);
@@ -83,6 +84,21 @@ struct ioevent_notify_entry
     struct nio_thread_data *thread_data;
 };
 
+struct fast_net_buffer
+{
+    int size;      //alloc size
+    int length;    //data length
+    int offset;    //current offset
+    char *data;    //buffer for write or read
+};
+
+struct fast_net_buffer_wrapper
+{
+    struct fast_net_buffer holder;
+    struct fast_net_buffer *ptr;
+};
+
+struct fast_task_queue;
 struct fast_task_info
 {
     IOEventEntry event;  //must first
@@ -91,7 +107,6 @@ struct fast_task_info
         char client_ip[IP_ADDRESS_SIZE];
     };
     void *arg;        //extra argument pointer
-    char *data;       //buffer for write or read
     char *recv_body;  //for extra (dynamic) recv buffer
 
     struct {
@@ -99,9 +114,9 @@ struct fast_task_info
         int count;
     } iovec_array; //for writev
 
-    int size;      //alloc size
-    int length;    //data length
-    int offset;    //current offset
+    struct fast_net_buffer_wrapper send;  //send buffer
+    struct fast_net_buffer_wrapper recv;  //recv buffer
+
     uint16_t port; //peer port
     struct {
         uint8_t current;
@@ -125,23 +140,20 @@ struct fast_task_info
     struct sf_network_handler *handler; //network handler for libserverframe nio
     struct fast_task_info *next;        //for free queue and deleted list
     struct fast_task_info *notify_next; //for nio notify queue
+    struct fast_task_queue *free_queue; //task allocator
     char conn[0];    //for RDMA connection
 };
 
 struct fast_task_queue
 {
-	struct fast_task_info *head;
-	struct fast_task_info *tail;
-	pthread_mutex_t lock;
-	int max_connections;
-	int alloc_connections;
-	int alloc_task_once;
-	int min_buff_size;
-	int max_buff_size;
+    int min_buff_size;
+    int max_buff_size;
     int padding_size;   //for last field: conn[0]
-	int arg_size;       //for arg pointer
-	int block_size;
-	bool malloc_whole_block;
+    int arg_size;       //for arg pointer
+    int block_size;
+    bool malloc_whole_block;
+    bool double_buffers;  //if send buffer and recv buffer are independent
+    struct fast_mblock_man allocator;
     TaskInitCallback init_callback;
 };
 
@@ -149,57 +161,119 @@ struct fast_task_queue
 extern "C" {
 #endif
 
-int free_queue_init_ex2(const int max_connections, const int init_connections,
+int free_queue_init_ex2(struct fast_task_queue *queue, const char *name,
+        const bool double_buffers, const int max_connections,
         const int alloc_task_once, const int min_buff_size,
         const int max_buff_size, const int padding_size,
         const int arg_size, TaskInitCallback init_callback);
 
-static inline int free_queue_init_ex(const int max_connections,
-        const int init_connections, const int alloc_task_once,
-        const int min_buff_size, const int max_buff_size, const int arg_size)
+static inline int free_queue_init_ex(struct fast_task_queue *queue,
+        const char *name, const bool double_buffers,
+        const int max_connections, const int alloc_task_once,
+        const int min_buff_size, const int max_buff_size,
+        const int arg_size)
 {
     const int padding_size = 0;
-    return free_queue_init_ex2(max_connections, init_connections,
-            alloc_task_once, min_buff_size, max_buff_size,
-            padding_size, arg_size, NULL);
+    return free_queue_init_ex2(queue, name, double_buffers, max_connections,
+            alloc_task_once, min_buff_size, max_buff_size, padding_size,
+            arg_size, NULL);
 }
 
-static inline int free_queue_init(const int max_connections,
-        const int min_buff_size, const int max_buff_size, const int arg_size)
+void free_queue_destroy(struct fast_task_queue *queue);
+
+static inline struct fast_task_info *free_queue_pop(
+        struct fast_task_queue *queue)
 {
-    const int padding_size = 0;
-    return free_queue_init_ex2(max_connections, max_connections, 0,
-            min_buff_size, max_buff_size, padding_size, arg_size, NULL);
+    return fast_mblock_alloc_object(&queue->allocator);
 }
 
-void free_queue_destroy();
+void free_queue_push(struct fast_task_info *task);
 
-int free_queue_push(struct fast_task_info *pTask);
-struct fast_task_info *free_queue_pop();
-int free_queue_count();
-int free_queue_alloc_connections();
-int free_queue_set_buffer_size(struct fast_task_info *pTask,
-        const int expect_size);
-int free_queue_realloc_buffer(struct fast_task_info *pTask,
-        const int expect_size);
+static inline int free_queue_count(struct fast_task_queue *queue)
+{
+    return queue->allocator.info.element_total_count -
+        queue->allocator.info.element_used_count;
+}
 
-int free_queue_set_max_buffer_size(struct fast_task_info *pTask);
+static inline int free_queue_alloc_connections(struct fast_task_queue *queue)
+{
+    return queue->allocator.info.element_total_count;
+}
 
-int free_queue_realloc_max_buffer(struct fast_task_info *pTask);
-
-int task_queue_init(struct fast_task_queue *pQueue);
-int task_queue_push(struct fast_task_queue *pQueue, \
-		struct fast_task_info *pTask);
-struct fast_task_info *task_queue_pop(struct fast_task_queue *pQueue);
-int task_queue_count(struct fast_task_queue *pQueue);
-int task_queue_set_buffer_size(struct fast_task_queue *pQueue,
-        struct fast_task_info *pTask, const int expect_size);
-int task_queue_realloc_buffer(struct fast_task_queue *pQueue,
-        struct fast_task_info *pTask, const int expect_size);
-
-int task_queue_get_new_buffer_size(const int min_buff_size,
+int free_queue_get_new_buffer_size(const int min_buff_size,
         const int max_buff_size, const int expect_size, int *new_size);
 
+int free_queue_set_buffer_size(struct fast_task_info *task,
+        struct fast_net_buffer *buffer, const int expect_size);
+
+static inline int free_queue_set_max_buffer_size(
+        struct fast_task_info *task,
+        struct fast_net_buffer *buffer)
+{
+    return free_queue_set_buffer_size(task, buffer,
+            task->free_queue->max_buff_size);
+}
+
+int free_queue_realloc_buffer(struct fast_task_info *task,
+        struct fast_net_buffer *buffer, const int expect_size);
+
+static inline int free_queue_realloc_max_buffer(
+        struct fast_task_info *task,
+        struct fast_net_buffer *buffer)
+{
+    return free_queue_realloc_buffer(task, buffer,
+            task->free_queue->max_buff_size);
+}
+
+/* send and recv buffer operations */
+static inline int free_queue_set_send_buffer_size(
+        struct fast_task_info *task, const int expect_size)
+{
+    return free_queue_set_buffer_size(task, task->send.ptr, expect_size);
+}
+
+static inline int free_queue_set_recv_buffer_size(
+        struct fast_task_info *task, const int expect_size)
+{
+    return free_queue_set_buffer_size(task, task->recv.ptr, expect_size);
+}
+
+static inline int free_queue_set_send_max_buffer_size(
+        struct fast_task_info *task)
+{
+    return free_queue_set_max_buffer_size(task, task->send.ptr);
+}
+
+static inline int free_queue_set_recv_max_buffer_size(
+        struct fast_task_info *task)
+{
+    return free_queue_set_max_buffer_size(task, task->recv.ptr);
+}
+
+static inline int free_queue_realloc_send_buffer(
+        struct fast_task_info *task, const int expect_size)
+{
+    return free_queue_realloc_buffer(task, task->send.ptr, expect_size);
+}
+
+static inline int free_queue_realloc_recv_buffer(
+        struct fast_task_info *task, const int expect_size)
+{
+    return free_queue_realloc_buffer(task, task->recv.ptr, expect_size);
+}
+
+static inline int free_queue_realloc_send_max_buffer(
+        struct fast_task_info *task)
+{
+    return free_queue_realloc_max_buffer(task, task->send.ptr);
+}
+
+static inline int free_queue_realloc_recv_max_buffer(
+        struct fast_task_info *task)
+{
+    return free_queue_realloc_max_buffer(task, task->recv.ptr);
+}
+
 #ifdef __cplusplus
 }
 #endif