我有一个经常用新条目填充的表。超过 2 天的记录每隔几分钟就会被删除：
DELETE FROM ip_log WHERE timestamp < NOW() - INTERVAL 2 DAY
这是按时间戳的唯一查询，此表上的其他查询在 IP 上，这是 PK（我想知道这个用户是新用户还是最近已经有活动）
timestamp 的索引应该是ASC还是DESC？
运行社区 8.0.14 的服务器，几天前我们达到了打开文件的数量，所以我增加了限制，但过了一会儿服务器在错误日志中崩溃了：
InnoDB: We intentionally generate a memory trap.
InnoDB: Submit a detailed bug report to http://bugs.mysql.com.
InnoDB: If you get repeated assertion failures or crashes, even
InnoDB: immediately after the mysqld startup, there may be
InnoDB: corruption in the InnoDB tablespace. Please refer to
InnoDB: http://dev.mysql.com/doc/refman/8.0/en/forcing-innodb-recovery.html
InnoDB: about forcing recovery.
03:07:21 UTC - mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
Attempting to collect some information that could help diagnose the problem.
As this is a crash and something is definitely wrong, the information
collection process might fail.
key_buffer_size=8388608
read_buffer_size=131072
max_used_connections=221
max_threads=1000
thread_count=4
connection_count=3
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 403301 K bytes of memory
Hope that's ok; if not, decrease some variables in the equation.
Thread pointer: 0x7f9200000b20
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = 7fd571ceaca0 thread_stack 0x46000
/usr/sbin/mysqld(my_print_stacktrace(unsigned char*, unsigned long)+0x3d) [0x561bdb69757d]
/usr/sbin/mysqld(handle_fatal_signal+0x423) [0x561bda8277c3]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x12890) [0x7fe5095f6890]
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0xc7) [0x7fe507981e97]
/lib/x86_64-linux-gnu/libc.so.6(abort+0x141) [0x7fe507983801]
/usr/sbin/mysqld(ut_dbg_assertion_failed(char const*, char const*, unsigned long)+0x2d5) [0x561bdb94d2c5]
/usr/sbin/mysqld(+0x1fe243c) [0x561bdb94f43c]
/usr/sbin/mysqld(mem_heap_create_block_func(mem_block_info_t*, unsigned long, unsigned long)+0x9ba) [0x561bdb95638a]
/usr/sbin/mysqld(mem_heap_add_block(mem_block_info_t*, unsigned long)+0x72) [0x561bdb956562]
/usr/sbin/mysqld(trx_undo_update_rec_get_update(unsigned char const*, dict_index_t*, unsigned long, unsigned long, unsigned long, unsigned long, trx_t*, mem_block_info_t*, upd_t**, lob::undo_vers_t*, type_cmpl_t&)+0x1926) [0x561bdb924896]
/usr/sbin/mysqld(row_purge_step(que_thr_t*)+0x845) [0x561bdb8b7ad5]
/usr/sbin/mysqld(que_run_threads(que_thr_t*)+0x997) [0x561bdb859597]
/usr/sbin/mysqld(srv_worker_thread()+0x29d) [0x561bdb8e85bd]
/usr/sbin/mysqld(std::thread::_State_impl<std::thread::_Invoker<std::tuple<Runnable, void (*)()> > >::_M_run()+0x63) [0x561bdb759883]
/usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0xbd57f) [0x7fe5083a757f]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x76db) [0x7fe5095eb6db]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x3f) [0x7fe507a6488f]
Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (0): Connection ID (thread ID): 0
Status: NOT_KILLED
The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains
information that should help you find out what is causing the crash.
2019-01-27T03:07:37.554520Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.14) starting as process 56489
InnoDB: Progress in percents: 1InnoDB MEMCACHED: Memcached uses atomic increment
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 1002019-01-27T03:12:07.973920Z 0 [System] [MY-010229] [Server] Starting crash recovery...
2019-01-27T03:12:07.982255Z 0 [System] [MY-010232] [Server] Crash recovery finished.
2019-01-27T03:12:10.581437Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed.
2
机器是 2x Xeon E5-2680v4 - 28c/56t - 2.4GHz /3.3GHz，512GB RAM，配置文件：
server-id = 1
log-bin = /var/lib/mysql-binlogs/web07
relay-log = web07-relay-bin
binlog_expire_logs_seconds = 259200
open_files_limit = 10000
max_connections = 1000
innodb_flush_method=O_DIRECT
innodb_flush_log_at_trx_commit=0
innodb_log_file_size=38G
innodb_buffer_pool_size=300G
innodb_buffer_pool_instances=64
join_buffer_size=5M
tmp_table_size=1G
max_heap_table_size=512M
skip_name_resolve=1
table_open_cache=20000
sql-mode="ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION,NO_AUTO_VALUE_ON_ZERO"
relay-log-recovery=1
default-authentication-plugin=mysql_native_password
在那次崩溃之后，如果我在打开的文件太多（大约每 24 小时一次）时不重新启动它，服务器会再次崩溃，例如：
$ mysql -e "show global status like 'open_%';"
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| Open_files | 62507 |
| Open_streams | 0 |
| Open_table_definitions | 1843 |
| Open_tables | 18779 |
| Opened_files | 71902 |
| Opened_table_definitions | 3168 |
| Opened_tables | 18803 |
+--------------------------+-------+
当我写这个问题时，服务器崩溃了：
2019-01-29T22:27:51.031406Z 54298197 [ERROR] [MY-013132] [Server] The table '/tmp/#sql9ae8_33c8655_13' is full!
2019-01-29T22:28:01.844610Z 54321796 [ERROR] [MY-013132] [Server] The table '/tmp/#sql9ae8_33ce284_1' is full!
如何调试为什么有这么多打开的文件？流量很大，但通常打开的连接不超过 10 个，为什么临时表没有关闭？
lsof：（~27k 总行，重启后 10 小时）
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mysqld 23964 mysql cwd DIR 9,3 4096 49549201 /var/lib/mysql
mysqld 23964 mysql rtd DIR 9,3 4096 2 /
mysqld 23964 mysql txt REG 9,3 56952368 6292097 /usr/sbin/mysqld
mysqld 23964 mysql DEL REG 9,3 12858561 /tmp/mysql_temptable.As3HWG
mysqld 23964 mysql DEL REG 9,3 12858557 /tmp/mysql_temptable.I4gP0F
mysqld 23964 mysql DEL REG 9,3 12858554 /tmp/mysql_temptable.W139aF
mysqld 23964 mysql DEL REG 9,3 12858553 /tmp/mysql_temptable.MhBwlE
mysqld 23964 mysql DEL REG 9,3 12858551 /tmp/mysql_temptable.mcw0vD
mysqld 23964 mysql DEL REG 9,3 12858550 /tmp/mysql_temptable.OFuZ94
mysqld 23964 mysql DEL REG 9,3 12858544 /tmp/mysql_temptable.2ffRvY
mysqld 23964 mysql DEL REG 9,3 12858549 /tmp/mysql_temptable.VvXQPw
mysqld 23964 mysql DEL REG 9,3 12858541 /tmp/mysql_temptable.KTTZRR
mysqld 23964 mysql DEL REG 9,3 12858542 /tmp/mysql_temptable.eMVSbq
mysqld 23964 mysql DEL REG 9,3 12858538 /tmp/mysql_temptable.6Kaay
在第一行之后，所有文件都被（删除）。我认为这是问题所在，为什么没有发布这些指针？
mysqld 27864 mysql 1658u REG 9,3 1048584 12846342 /tmp/mysql_temptable.wazlKx (deleted)
mysqld 27864 mysql 1660u REG 9,3 1048584 12846352 /tmp/mysql_temptable.S5Oo1m (deleted)
mysqld 27864 mysql 1662u REG 9,3 1048584 12846343 /tmp/mysql_temptable.l1CZjK (deleted)
mysqld 27864 mysql 1666u REG 9,3 1048584 12846366 /tmp/mysql_temptable.VDaTxb (deleted)
2019-02-19：我按照建议增加了一些限制，并做了一个mysqlcheck --all-databases，没有任何变化。
正如评论中所写，即使我停止流量，打开文件的数量也不会减少。
该应用程序被证明是稳定的，并且在问题出现之前的几天内，代码或流量没有发生重大变化。（我 100% 确定，因为那天是假期，主分支上没有提交）
