我正在使用Google Cloud SQL（5.5）并经常发生“等待表格元数据锁定”。
我阅读了this page和this post，并查看了general_log。
以下是general_log的摘录。
:
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Close stmt',''),
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Prepare','SELECT * FROM .....'),
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Execute','SELECT * FROM .....'),
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Close stmt',''),
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Prepare','SELECT * FROM .....),
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Execute','SELECT * FROM .....'),
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Close stmt',''),
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Prepare','SELECT * FROM .....'),
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Execute','SELECT * FROM .....'),
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Close stmt',''),
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Prepare','SELECT * FROM .....'),
('2015-06-03 07:15:25','root[root] @ localhost []',1081,1791318620,'Execute','SELECT * FROM .....'),
('2015-06-03 07:17:11','[root] @ localhost []',2,1791318620,'Connect','root@localhost on mydb'),
('2015-06-03 07:17:11','[root] @ localhost []',3,1791318620,'Connect','root@localhost on mydb'),
('2015-06-03 07:17:32','root[root] @ localhost []',2,1791318620,'Query','set autocommit=1'),
('2015-06-03 07:17:32','root[root] @ localhost []',3,1791318620,'Query','set autocommit=1'),
('2015-06-03 07:17:32','root[root] @ localhost []',1,1791318620,'Query','set autocommit=1'),
('2015-06-03 07:17:32','root[root] @ localhost []',3,1791318620,'Query','SET sql_mode=\'STRICT_TRANS_TABLES\''),
('2015-06-03 07:17:32','root[root] @ localhost []',2,1791318620,'Query','SET sql_mode=\'STRICT_TRANS_TABLES\''),
('2015-06-03 07:17:32','root[root] @ localhost []',1,1791318620,'Query','SET sql_mode=\'STRICT_TRANS_TABLES\''),
('2015-06-03 07:17:32','root[root] @ localhost []',3,1791318620,'Query','commit'),
('2015-06-03 07:17:32','root[root] @ localhost []',2,1791318620,'Query','commit'),
('2015-06-03 07:17:32','root[root] @ localhost []',1,1791318620,'Query','commit'),
('2015-06-03 07:17:32','root[root] @ localhost []',3,1791318620,'Query','SET NAMES utf8mb4'),
('2015-06-03 07:17:32','root[root] @ localhost []',2,1791318620,'Query','SET NAMES utf8mb4'),
('2015-06-03 07:17:32','root[root] @ localhost []',1,1791318620,'Query','SET NAMES utf8mb4'),
('2015-06-03 07:17:32','[root] @ localhost []',4,1791318620,'Connect','root@localhost on mydb'),
('2015-06-03 07:17:32','[root] @ localhost []',5,1791318620,'Connect','root@localhost on mydb'),
('2015-06-03 07:17:33','root[root] @ localhost []',5,1791318620,'Query','set autocommit=1'),
('2015-06-03 07:17:33','root[root] @ localhost []',4,1791318620,'Query','set autocommit=1'),
('2015-06-03 07:17:33','root[root] @ localhost []',5,1791318620,'Query','SET sql_mode=\'STRICT_TRANS_TABLES\''),
('2015-06-03 07:17:33','root[root] @ localhost []',4,1791318620,'Query','SET sql_mode=\'STRICT_TRANS_TABLES\''),
('2015-06-03 07:17:33','root[root] @ localhost []',5,1791318620,'Query','commit'),
('2015-06-03 07:17:33','root[root] @ localhost []',4,1791318620,'Query','commit'),
('2015-06-03 07:17:33','root[root] @ localhost []',5,1791318620,'Query','SET NAMES utf8mb4'),
:
从07:15:25到07:17:11没有日志但我的应用程序发出查询并且没有问题。
围绕general_log恢复（07:17或07:18），我的应用程序停滞不前，show processlist显示“等待表元数据锁定。”
我知道DDL导致“等待表元数据锁定。”，但我确信我没有执行任何DDL。
我的猜测是丢失了general_log导致“等待表元数据锁定。”，但我不确定为什么会发生日志丢失。
我猜对了吗？如果是这样，为什么会发生损失？ 或者还有其他原因吗？
[更新]
show processlist如下所示。
+----+------+-----------------+------+---------+------+---------------------------------+-------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------------+------+---------+------+---------------------------------+-------------------+
| 1 | root | localhost | mydb | Execute | 335 | Waiting for table metadata lock | SELECT * FROM ... |
| 2 | root | localhost | mydb | Execute | 358 | Waiting for table metadata lock | SELECT * FROM ... |
| 4 | root | localhost | mydb | Prepare | 359 | Opening table | NULL |
| 6 | root | localhost | mydb | Prepare | 347 | Waiting for table metadata lock | NULL |
| 7 | root | localhost | mydb | Execute | 346 | Waiting for table metadata lock | SELECT * FROM ... |
| 8 | root | localhost | mydb | Execute | 335 | Waiting for table metadata lock | SELECT ... |
| 9 | root | localhost | mydb | Execute | 320 | Waiting for table metadata lock | SELECT ... |
| 11 | root | localhost | mydb | Execute | 299 | Waiting for table metadata lock | SELECT * FROM ... |
| 12 | root | localhost | mydb | Prepare | 299 | Waiting for table metadata lock | NULL |
| 13 | root | localhost | mydb | Execute | 279 | Waiting for table metadata lock | SELECT * FROM ... |
| 14 | root | localhost | mydb | Execute | 269 | Waiting for table metadata lock | SELECT * FROM ... |
| 16 | root | localhost | mydb | Sleep | 240 | | NULL |
| 17 | root | localhost | mydb | Execute | 209 | Waiting for table metadata lock | SELECT * FROM ... |
| 19 | root | localhost | mydb | Execute | 203 | Waiting for table metadata lock | SELECT ... |
| 21 | root | localhost | mydb | Execute | 200 | Waiting for table metadata lock | SELECT * FROM ... |