追踪MySQL中长时间运行的事务

接上一篇，未提交的事务导致锁等待，锁住一段时间后又提交了（也可能是回滚），锁释放业务继续运行。那么我们如何知道产生锁的事务是在跑什么SQL？

今天讲的这个工具，就可以通过监听3306端口的数据，把每个事务的起始时间，SQL命令都打印出来，而且可以设置事务时长，比如事务时长超过10秒的。

参考链接：https://highdb.com/%E8%BF%BD%E8%B8%AAmysql%E4%B8%AD%E9%95%BF%E6%97%B6%E9%97%B4%E8%BF%90%E8%A1%8C%E7%9A%84%E4%BA%8B%E5%8A%A1/

github链接：https://github.com/yoshinorim/MySlowTranCapture,下载后解压

---

#安装

How to use:
* Install libpcap, libpcap-devel, boost, and boost-devel if not installed
* make
* make install
* Run myslowtrancapture

#运行

[root@xxxx MySlowTranCapture-master]# myslowtrancapture -f "tcp port 3306"
Monitoring any interface..
Filtering rule: tcp port
Logging transactions that take more than  milliseconds..
 ........开始等待符合条件的输出

#默认检测事务时长是4秒，我们构造一个显式事务，持续时间5秒，看看输出结果

#MYSQL SESSION
mysql> select * from t1;
+------+
| id   |
+------+
|     |
|     |
+------+
 rows in set (0.00 sec)

mysql> begin;delete from t1 where id=;select sleep();rollback;
Query OK,  rows affected (0.00 sec)

Query OK,  row affected (0.00 sec)

+----------+
| sleep() |
+----------+
|         |
+----------+
 row in set (5.00 sec)

Query OK,  rows affected (0.00 sec)

mysql> 

From 10.3.171.21:
// ::18.679918 ->
begin                         #事务开始
// ::18.679992 <-
GOT_OK
// ::18.679995 <-
GOT_OK
// ::18.680104 ->
delete from t1 where id=     #这里看到了事务SQL
// ::18.680336 <-
GOT_OK
// ::18.680342 <-
GOT_OK
// ::18.680477 ->
select sleep()
// ::23.680669 <-
GOT_RES
// ::23.680677 <-
GOT_RES
// ::23.680973 ->
rollback                      #事务回滚

#事务时长=11:25:23-11:25:18=5秒

除了rollback,commit之外，给当前session设置autocommit=0/1,也会提交当前事务-------这句话有问题，单独开事务测试并没有提交，在这里看日志又像是事务终止了，需要再调查下。

From 10.3.171.21:
// ::37.484762 ->
begin
// ::37.484806 <-
GOT_OK
// ::37.484808 <-
GOT_OK
// ::37.484958 ->
delete from test
// ::37.485061 <-
GOT_OK
// ::37.485063 <-
GOT_OK
// ::37.485167 ->
select sleep()
// ::57.485276 <-
GOT_RES
// ::57.485279 <-
GOT_RES
// ::57.485442 ->
TRAN_END BY set autocommit=     #set autocommit=

From 10.3.139.151:

产生上面输出的SQL是这样的：

mysql> begin;delete from test;select sleep();set autocommit=;
Query OK,  rows affected (0.00 sec)

Query OK,  rows affected (0.00 sec)

+------------+
| sleep() |
+------------+
|           |
+------------+
 row in set ( min 19.98 sec)

Query OK,  rows affected (0.00 sec)

mysql>