diff --git a/lib_acl_cpp/include/acl_cpp/connpool/connect_monitor.hpp b/lib_acl_cpp/include/acl_cpp/connpool/connect_monitor.hpp
index b6ad6f42d..89ff27178 100644
--- a/lib_acl_cpp/include/acl_cpp/connpool/connect_monitor.hpp
+++ b/lib_acl_cpp/include/acl_cpp/connpool/connect_monitor.hpp
@@ -63,7 +63,6 @@ public:
 	 * @param on {bool} 是否自动关闭过期的空闲连接
 	 * @param kick_dead {bool} 是否检查所有连接的存活状态并关闭异常连接，当该参数
 	 *  为 true 时，connect_client 的子类必须重载 alive() 虚方法，返回连接是否存活
-	 * @param conns_min {size_t} > 0 表示尽量维持每个连接池中的最小活跃连接数
 	 * @param step {bool} 每次检测连接池个数
 	 * @return {connect_monitor&}
 	 */
diff --git a/lib_acl_cpp/include/acl_cpp/connpool/connect_pool.hpp b/lib_acl_cpp/include/acl_cpp/connpool/connect_pool.hpp
index 3a904dc9f..73972fc2b 100644
--- a/lib_acl_cpp/include/acl_cpp/connpool/connect_pool.hpp
+++ b/lib_acl_cpp/include/acl_cpp/connpool/connect_pool.hpp
@@ -101,19 +101,41 @@ public:
 	void put(connect_client* conn, bool keep = true);
 
 	/**
-	 * 检查连接池中空闲的连接，将过期的连接释放掉
-	 * @param kick_dead {bool} 是否自动检测死连接并关闭之
+	 * 检查连接池中空闲的连接，释放过期连接（过期时间使用 set_idle_ttl() 设置的值）
 	 * @param exclusive {bool} 内部是否需要加锁
-	 * @return {size_t} 被释放的空闲连接个数
+	 * @param kick_dead {bool} 是否自动检测死连接并关闭之
+	 * @return {size_t} 返回被释放空闲连接个数
 	 */
-	size_t check_idle(bool kick_dead, bool exclusive);
+	size_t check_idle(bool kick_dead, bool exclusive = true);
 
 	/**
-	 * 检测连接状态，并关闭断开连接
+	 * 检查连接池中空闲的连接，释放过期连接
+	 * @param ttl {time_t} 该值 >= 0 时，过期时间大于此值的连接将被关闭
 	 * @param exclusive {bool} 内部是否需要加锁
+	 * @param kick_dead {bool} 是否自动检测死连接并关闭之
+	 * @return {size_t} 返回被释放空闲连接个数
+	 */
+	size_t check_idle(time_t ttl, bool kick_dead, bool exclusive = true);
+
+	/**
+	 * 检查连接池中空闲的连接，释放过期连接
+	 * @param ttl {time_t} 该值 >= 0 时，过期时间大于此值的连接将被关闭
+	 * @param exclusive {bool} 内部是否需要加锁
+	 * @return {size_t} 返回被释放空闲连接个数
+	 */
+	size_t check_idle(time_t ttl, bool exclusive = true);
+
+	/**
+	 * 检测连接状态，并关闭断开连接，内部自动加锁保护
+	 * @param count {size_t} 检测的连接个数，缺省值为 0 表示检测所有连接
 	 * @return {size_t} 被关闭的连接个数
 	 */
-	size_t check_dead(bool exclusive = true);
+	size_t check_dead(size_t count = 0);
+
+	/**
+	 * 尽量保持由 set_conns_min() 设置的最小连接数
+	 */
+	void keep_conns();
 
 	/**
 	 * 设置连接池的存活状态
@@ -232,13 +254,7 @@ protected:
 	std::list<connect_client*> pool_;	// 连接池集合
 
 	size_t kick_idle_conns(time_t ttl);	// 关闭过期的连接
-
-	/**
-	 * 保持最小活跃连接数
-	 * @param min {size_t} 该值 > 0 表示希望连接池中最小的活跃连接数
-	 * @return {size_t} 返回实际的连接数
-	 */
-	size_t keep_conns(size_t min);
+	connect_client* peek_back();		// 从尾部 Peek 连接
 };
 
 class ACL_CPP_API connect_guard : public noncopyable {
diff --git a/lib_acl_cpp/src/connpool/connect_pool.cpp b/lib_acl_cpp/src/connpool/connect_pool.cpp
index cc869d7bc..39e2c4094 100644
--- a/lib_acl_cpp/src/connpool/connect_pool.cpp
+++ b/lib_acl_cpp/src/connpool/connect_pool.cpp
@@ -324,13 +324,23 @@ void connect_pool::set_alive(bool yes /* true | false */)
 	lock_.unlock();
 }
 
-size_t connect_pool::check_idle(bool kick_dead, bool exclusive)
+size_t connect_pool::check_idle(time_t ttl, bool exclusive /* true */)
+{
+	return check_idle(ttl, false, exclusive);
+}
+
+size_t connect_pool::check_idle(bool kick_dead, bool exclusive /* true */)
+{
+	return check_idle(idle_ttl_, kick_dead, exclusive);
+}
+
+size_t connect_pool::check_idle(time_t ttl, bool kick_dead, bool exclusive)
 {
 	if (exclusive) {
 		lock_.lock();
 	}
 
-	if (pool_.empty()) {
+	if (pool_.empty() && min_ == 0) {
 		if (exclusive) {
 			lock_.unlock();
 		}
@@ -339,7 +349,7 @@ size_t connect_pool::check_idle(bool kick_dead, bool exclusive)
 
 	size_t n = 0;
 
-	if (idle_ttl_ == 0) {
+	if (ttl == 0) {
 		std::list<connect_client*>::iterator it = pool_.begin();
 		for (; it != pool_.end(); ++it) {
 			delete *it;
@@ -355,22 +365,24 @@ size_t connect_pool::check_idle(bool kick_dead, bool exclusive)
 		return n;
 	}
 
-	if (idle_ttl_ > 0) {
-		n += kick_idle_conns(idle_ttl_);
+	if (ttl > 0) {
+		n += kick_idle_conns(ttl);
 	}
 
-	if (kick_dead) {
-		n += check_dead(false);
-	}
-
-	if (min_ > 0) {
-		keep_conns(min_);
-	}
+	size_t count = count_;
 
 	if (exclusive) {
 		lock_.unlock();
 	}
 
+	if (kick_dead) {
+		n += check_dead(count);
+	}
+
+	if (min_ > 0) {
+		keep_conns();
+	}
+
 	return n;
 }
 
@@ -414,62 +426,85 @@ size_t connect_pool::kick_idle_conns(time_t ttl)
 	return n;
 }
 
-size_t connect_pool::check_dead(bool exclusive /* true */)
+size_t connect_pool::check_dead(size_t count /* 0 */)
 {
-	if (exclusive) {
+	if (count == 0) {
 		lock_.lock();
+		count = count_;
+		lock_.unlock();
 	}
 
 	size_t n = 0;
-	std::list<connect_client*>::iterator it;
+	for (size_t i = 0; i < count; i++) {
+		connect_client* conn = peek_back();
+		if (conn == NULL) {
+			break;
+		}
 
-	// Check all the dead connections and close them.
-	for (it = pool_.begin(); it != pool_.end();) {
-		if ((*it)->alive()) {
-			++it;
+		if (conn->alive()) {
+			put(conn);
 			continue;
 		}
 
-		if ((*it)->get_pool() == this) {
-			count_--;
+		if (conn->get_pool() == this) {
+			lock_.lock();
+			--count_;
+			lock_.unlock();
 		}
-
-		delete *it;
-		it = pool_.erase(it);
+		delete conn;
 		n++;
 	}
 
-	if (exclusive) {
-		lock_.unlock();
-	}
 	return n;
 }
 
-size_t connect_pool::keep_conns(size_t min)
+connect_client* connect_pool::peek_back()
 {
-	if (min > 0 && min > count_) {
-		min -= count_;
+	lock_.lock();
+	std::list<connect_client*>::reverse_iterator rit = pool_.rbegin();
+	if (rit == pool_.rend()) {
+		lock_.unlock();
+		return NULL;
+	}
+
+	std::list<connect_client*>::iterator it = --rit.base();
+	connect_client* conn = *it;
+	pool_.erase(it);
+	lock_.unlock();
+	return conn;
+}
+
+void connect_pool::keep_conns()
+{
+	lock_.lock();
+	size_t min;
+	if (min_ > 0 && min_ > count_) {
+		min = min_ - count_;
 	} else {
 		min = 0;
 	}
+	lock_.unlock();
 
 	for (size_t i = 0; i < min; i++) {
 		connect_client* conn = create_connect();
 		if (conn == NULL) {
+			logger_error("Create connection error");
 			break;
 		}
+
 		if (!conn->open()) {
-			logger_error("Open connection error, conn=%p", conn);
+			logger_error("Open error: %s", last_serror());
 			delete conn;
 			break;
 		}
 
+		lock_.lock();
 		count_++;
+		lock_.unlock();
 
 		conn->set_pool(this);
 		put(conn, true);
 	}
-	return count_;
 }
 
 } // namespace acl
diff --git a/lib_acl_cpp/src/connpool/tcp_ipc.cpp b/lib_acl_cpp/src/connpool/tcp_ipc.cpp
index cbfa279ac..6750772f2 100644
--- a/lib_acl_cpp/src/connpool/tcp_ipc.cpp
+++ b/lib_acl_cpp/src/connpool/tcp_ipc.cpp
@@ -10,7 +10,7 @@
 
 namespace acl {
 
-tcp_ipc::tcp_ipc(void)
+tcp_ipc::tcp_ipc()
 : max_(0)
 , ttl_(60)
 , conn_timeout_(10)
diff --git a/unit_test/net/test_net.c b/unit_test/net/test_net.c
index ddc909adf..7ae8dd78c 100644
--- a/unit_test/net/test_net.c
+++ b/unit_test/net/test_net.c
@@ -8,7 +8,7 @@
 #include "test_net.h"
 #include "test_nettab.h"
 
-void test_net_register()
+void test_net_register(void)
 {
 	aut_register(__test_fn_tab);
 }
diff --git a/unit_test/stdlib/test_avl.c b/unit_test/stdlib/test_avl.c
index c71a474a6..0e9686f1e 100644
--- a/unit_test/stdlib/test_avl.c
+++ b/unit_test/stdlib/test_avl.c
@@ -53,7 +53,7 @@ int test_avl_create(AUT_LINE *test_line acl_unused, void *arg acl_unused)
 int test_avl_add_bat(AUT_LINE *test_line acl_unused, void *arg acl_unused)
 {
 	MY_TYPE *pm, m;
-	int   i, n = 0;
+	int   i;
 
 	for (i = 0; i < 100; i++) {
 		snprintf(m.name, sizeof(m.name), "%d", i);
@@ -69,7 +69,6 @@ int test_avl_add_bat(AUT_LINE *test_line acl_unused, void *arg acl_unused)
 		snprintf(pm->value, sizeof(pm->value), "value(%d)", i);
 		acl_avl_add(__avl_tree, pm);
 		printf(">>add one, key(%s), value(%s)\r\n", pm->name, pm->value);
-		n++;
 	} 
 
 	return (0);
diff --git a/unit_test/stdlib/test_stdlib.c b/unit_test/stdlib/test_stdlib.c
index 127844aa8..c28061fcf 100644
--- a/unit_test/stdlib/test_stdlib.c
+++ b/unit_test/stdlib/test_stdlib.c
@@ -9,7 +9,7 @@
 
 #include "test_stdtab.h"
 
-void test_stdlib_register()
+void test_stdlib_register(void)
 {
 	aut_register(__test_fn_tab);
 }
diff --git a/unit_test/unit_test/unit_test.c b/unit_test/unit_test/unit_test.c
index 64a477d1e..bbee9dc1e 100644
--- a/unit_test/unit_test/unit_test.c
+++ b/unit_test/unit_test/unit_test.c
@@ -3,7 +3,7 @@
 #include "unit_test.h"
 #include "unit_test_tab.h"
 
-void test_unit_register()
+void test_unit_register(void)
 {
 	aut_register(__test_fn_tab);
 }