我正在尝试学习如何在 MySQL 5.6 中使用 memcached 插件。我使用 telnet 来获取和设置 memcached 的值。当我尝试从 memcache 获取过期值时，它显示“连接已被外部主机关闭。”。更多详情如下:
数据库名称:测试
表名:demo
我的表描述
+-------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------+------+-----+---------+-------+
| c1 | varchar(32) | NO | PRI | NULL | |
| c21 | varchar(1024) | YES | | NULL | |
| c22 | varchar(1024) | YES | | NULL | |
| c3 | int(11) | YES | | NULL | |
| c4 | bigint(20) unsigned | YES | | NULL | |
| c5 | int(11) | YES | | NULL | |
+-------+---------------------+------+-----+---------+-------+
我的表格内容
+----+------+------+------+------+------------+
| c1 | c21 | c22 | c3 | c4 | c5 |
+----+------+------+------+------+------------+
| a | aaaa | aaaa | 0 | 1 | 0 |
| b | aa | aa | 0 | 2 | 1390372227 |
+----+------+------+------+------+------------+
容器表
+------+-----------+-----------+-------------+---------------+-------+------------+--------------------+------------------------+
| name | db_schema | db_table | key_columns | value_columns | flags | cas_column | expire_time_column | unique_idx_name_on_key |
+------+-----------+-----------+-------------+---------------+-------+------------+--------------------+------------------------+
| aaa | test | demo_test | c1 | c2 | c3 | c4 | c5 | PRIMARY |
| bb | test | demo | c1 | c21,c22 | c3 | c4 | c5 | PRIMARY |
+------+-----------+-----------+-------------+---------------+-------+------------+--------------------+------------------------+
缓存策略表
+--------------+-------------+-------------+---------------+--------------+
| policy_name | get_policy | set_policy | delete_policy | flush_policy |
+--------------+-------------+-------------+---------------+--------------+
| cache_policy | innodb_only | innodb_only | innodb_only | innodb_only |
+--------------+-------------+-------------+---------------+--------------+
远程登录
~ ⮀ telnet localhost 11211
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
get @@bb
VALUE @@bb 0 9
test/demo
END
get a
VALUE a 0 9
aaaa|aaaa
END
get c
END
get d
END
get b
Connection closed by foreign host.
当我尝试获取 memcached 中不存在的值时，或者当我尝试获取未过期的值时，没有问题。此外，这只发生在具有多个值列的表(此处为 c21 和 c22 )的情况下。如果我对只有一个值列的表执行相同操作，则没有问题。
并且在连接关闭后，如果我尝试查询数据库，则会显示以下错误:
mysql> select * from innodb_memcache.cache_policies;
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id: 1
Current database: test
而且有时会显示如下错误:
*** glibc detected *** /opt/mysql/server-5.6/bin/mysqld: free(): invalid pointer: 0x00007f053c008827 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x7eb96)[0x7f0596f39b96]
/opt/mysql/server-5.6/lib/plugin//innodb_engine.so(+0xb170)[0x7f0547df3170]
/opt/mysql/server-5.6/lib/plugin/libmemcached.so(+0x10bbb)[0x7f0569475bbb]
/opt/mysql/server-5.6/lib/plugin/libmemcached.so(+0x157b0)[0x7f056947a7b0]
/opt/mysql/server-5.6/lib/plugin/libmemcached.so(+0x16cec)[0x7f056947bcec]
/opt/mysql/server-5.6/lib/plugin/libmemcached.so(conn_parse_cmd+0x11)[0x7f056947c931]
/opt/mysql/server-5.6/lib/plugin/libmemcached.so(+0x9bdc)[0x7f056946ebdc]
/opt/mysql/server-5.6/lib/plugin/libmemcached.so(event_base_loop+0x286)[0x7f05694810d6]
/opt/mysql/server-5.6/lib/plugin/libmemcached.so(+0x19bb2)[0x7f056947ebb2]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x7e9a)[0x7f05982dbe9a]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f0596faf3fd]
======= Memory map: ========
00400000-00f6f000 r-xp 00000000 08:03 21495897 /opt/mysql/server-5.6/bin/mysqld
0116f000-0131a000 rw-p 00b6f000 08:03 21495897 /opt/mysql/server-5.6/bin/mysqld
0131a000-0136d000 rw-p 00000000 00:00 0
01a44000-021a0000 rw-p 00000000 00:00 0 [heap]
7f0534000000-7f0534021000 rw-p 00000000 00:00 0
7f0534021000-7f0538000000 ---p 00000000 00:00 0
7f053c000000-7f053c021000 rw-p 00000000 00:00 0
7f053c021000-7f0540000000 ---p 00000000 00:00 0
7f0540000000-7f05402dd000 rw-p 00000000 00:00 0
7f05402dd000-7f0544000000 ---p 00000000 00:00 0
7f05445e1000-7f05445e2000 ---p 00000000 00:00 0
7f05445e2000-7f0544de2000 rw-p 00000000 00:00 0 [stack:30166]
7f0544de2000-7f0544de3000 ---p 00000000 00:00 0
7f0544de3000-7f05455e3000 rw-p 00000000 00:00 0 [stack:30160]
7f05455e3000-7f05455e4000 ---p 00000000 00:00 0
7f05455e4000-7f0545de4000 rw-p 00000000 00:00 0 [stack:30161]
7f0545de4000-7f0545de5000 ---p 00000000 00:00 0
7f0545de5000-7f05465e5000 rw-p 00000000 00:00 0 [stack:30162]
7f05465e5000-7f05465e6000 ---p 00000000 00:00 0
7f05465e6000-7f0546de6000 rw-p 00000000 00:00 0 [stack:30163]
7f0546de6000-7f0546de7000 ---p 00000000 00:00 0
7f0546de7000-7f05475e7000 rw-p 00000000 00:00 0 [stack:30165]
7f05475e7000-7f05475e8000 ---p 00000000 00:00 0
7f05475e8000-7f0547de8000 rw-p 00000000 00:00 0 [stack:30164]
7f0547de8000-7f0547e00000 r-xp 00000000 08:03 21505464 /opt/mysql/server-5.6/lib/plugin/innodb_engine.so
7f0547e00000-7f0547fff000 ---p 00018000 08:03 21505464 /opt/mysql/server-5.6/lib/plugin/innodb_engine.so
7f0547fff000-7f0548000000 rw-p 00017000 08:03 21505464 /opt/mysql/server-5.6/lib/plugin/innodb_engine.so
7f0548000000-7f0548022000 rw-p 00000000 00:00 0
7f0548022000-7f054c000000 ---p 00000000 00:00 0
7f054c000000-7f054c021000 rw-p 00000000 00:00 0
7f054c021000-7f0550000000 ---p 00000000 00:00 0
7f0550000000-7f0550021000 rw-p 00000000 00:00 0
7f0550021000-7f0554000000 ---p 00000000 00:00 0
7f0554000000-7f0554021000 rw-p 00000000 00:00 0
7f0554021000-7f0558000000 ---p 00000000 00:00 0
7f0558000000-7f0558021000 rw-p 00000000 00:00 0
7f0558021000-7f055c000000 ---p 00000000 00:00 0
7f055c000000-7f055c07a000 rw-p 00000000 00:00 0
7f055c07a000-7f0560000000 ---p 00000000 00:00 0
7f0560000000-7f0560021000 rw-p 00000000 00:00 0
7f0560021000-7f0564000000 ---p 00000000 00:00 0
7f0564041000-7f0564042000 ---p 00000000 00:00 0
7f0564042000-7f0564842000 rw-p 00000000 00:00 0
7f0564842000-7f0564843000 ---p 00000000 00:00 0
7f0564843000-7f0565043000 rw-p 00000000 00:00 0 [stack:19202]
7f0565043000-7f0565044000 ---p 00000000 00:00 0
7f0565044000-7f0565844000 rw-p 00000000 00:00 0 [stack:19201]
7f0565844000-7f0565845000 ---p 00000000 00:00 0
7f0565845000-7f0566045000 rw-p 00000000 00:00 0 [stack:19200]
7f0566045000-7f0566046000 ---p 00000000 00:00 0
7f0566046000-7f0566846000 rw-p 00000000 00:00 0 [stack:19199]
7f0566846000-7f0566847000 ---p 00000000 00:00 0
7f0566847000-7f0567047000 rw-p 00000000 00:00 0 [stack:19198]
7f0567047000-7f0567048000 ---p 00000000 00:00 0
7f0567048000-7f0567848000 rw-p 00000000 00:00 0 [stack:19197]
7f0567848000-7f0567849000 ---p 00000000 00:00 0
7f0567849000-7f0568049000 rw-p 00000000 00:00 0 [stack:19196]
7f0568049000-7f056804a000 ---p 00000000 00:00 0
7f056804a000-7f056884a000 rw-p 00000000 00:00 0 [stack:19195]
7f056884a000-7f056884b000 ---p 00000000 00:00 0
7f056884b000-7f05692d8000 rw-p 00000000 00:00 0 [stack:19194]
7f0569465000-7f056948f000 r-xp 00000000 08:03 21505461 /opt/mysql/server-5.6/lib/plugin/libmemcached.so
7f056948f000-7f056968f000 ---p 0002a000 08:03 21505461 /opt/mysql/server-5.6/lib/plugin/libmemcached.so
7f056968f000-7f0569691000 rw-p 0002a000 08:03 21505461 /opt/mysql/server-5.6/lib/plugin/libmemcached.so
7f0569691000-7f0569694000 rw-p 00000000 00:00 0
7f0569694000-7f0569695000 ---p 00000000 00:00 0
7f0569695000-7f05696c5000 rw-p 00000000 00:00 0 [stack:20139]
7f05696c5000-7f05696c6000 ---p 00000000 00:00 0
7f05696c6000-7f05696f6000 rw-p 00000000 00:00 0 [stack:19203]
7f05696f6000-7f05696f7000 ---p 00000000 00:00 0
7f05696f7000-7f0569ef7000 rw-p 00000000 00:00 0 [stack:19192]
7f0569ef7000-7f0569ef8000 ---p 00000000 00:00 0
7f0569ef8000-7f056a6f8000 rw-p 00000000 00:00 0 [stack:19191]
7f056a6f8000-7f056a6f9000 ---p 00000000 00:00 0
7f056a6f9000-7f056aef9000 rw-p 00000000 00:00 0 [stack:19190]
7f056aef9000-7f056aefa000 ---p 00000000 00:00 0
7f056aefa000-7f056b6fa000 rw-p 00000000 00:00 0 [stack:19189]
7f056b6fa000-7f056b6fb000 ---p 00000000 00:00 0
7f056b6fb000-7f056befb000 rw-p 00000000 00:00 0 [stack:19188]
7f056befb000-7f056befc000 ---p 00000000 00:00 0
7f056befc000-7f056c6fc000 rw-p 00000000 00:00 0 [stack:19187]
7f056c6fc000-7f056c6fd000 ---p 00000000 00:00 0
7f056c6fd000-7f056cefd000 rw-p 00000000 00:00 0 [stack:19186]
7f056cefd000-7f056cefe000 ---p 00000000 00:00 0
7f056cefe000-7f056d6fe000 rw-p 00000000 00:00 0 [stack:19185]
最佳答案
这是一个错误，由于您发布的服务器崩溃日志，您的连接正在关闭。
这个问题是已知的，希望在未来的版本中得到修复，同时您可以避免使用表前缀 (@@bb)，因为这是问题的关键。
关于mysql - 尝试从 memcached 检索过期对象时出错，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/21325148/
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