最近，我托管在 Ubuntu 服务器上的网站开始显示“建立数据库连接时错误”。
连接到服务器，看起来 mysql 正在不断重启（3 秒前、20 秒前等，每次我尝试此命令时）：
sudo systemctl status mysql.service
mysql.service - MySQL Community Server
Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
Active: activating (start) since Fri 2023-09-15 14:31:16 UTC; 3s ago
Process: 8351 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
Main PID: 8362 (mysqld)
Status: "Server startup in progress"
Tasks: 12 (limit: 4541)
Memory: 318.8M
CGroup: /system.slice/mysql.service
└─8362 /usr/sbin/mysqld
我的 /var/log/mysql/error.log 文件也在快速增长。它包含许多奇怪的字符，后面跟着文本，例如：
InnoDB: End of page dump
InnoDB: Page may be a transaction system page
2023-09-15T14:33:15.169775Z 1 [ERROR] [MY-011899] [InnoDB] [FATAL] Unable to read page [page id: space=0, page number=5] into the buffer pool after 100 attempts. The most probable cause of this error may be that the table has been corrupted. Or, the table was compressed with with an algorithm that is not supported by this instance. If it is not a decompress failure, you can try to fix this problem by using innodb_force_recovery. Please see http://dev.mysql.com/doc/refman/8.0/en/ for more details. Aborting...
2023-09-15T14:33:15.169807Z 1 [ERROR] [MY-013183] [InnoDB] Assertion failure: buf0buf.cc:4054:ib::fatal triggered thread 140275780638464
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.
2023-09-15T14:33:15Z UTC - mysqld got signal 6 ;
Most likely, you have hit a bug, but this error can also be caused by malfunctioning hardware.
BuildID[sha1]=b0a6398207071378976beb42c50ef89be92e92db
Thread pointer: 0x5580f6f1c3f0
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 = 7f9480134be0 thread_stack 0x100000
/usr/sbin/mysqld(my_print_stacktrace(unsigned char const*, unsigned long)+0x41) [0x5580f29d9e71]
/usr/sbin/mysqld(print_fatal_signal(int)+0x39b) [0x5580f184efab]
/usr/sbin/mysqld(my_server_abort()+0x76) [0x5580f184f0f6]
/usr/sbin/mysqld(my_abort()+0xe) [0x5580f29d3e0e]
/usr/sbin/mysqld(ut_dbg_assertion_failed(char const*, char const*, unsigned long)+0x349) [0x5580f2c77929]
/usr/sbin/mysqld(ib::fatal::~fatal()+0xd5) [0x5580f2c7a165]
/usr/sbin/mysqld(Buf_fetch<Buf_fetch_normal>::read_page()+0x1aa) [0x5580f2ce2fba]
/usr/sbin/mysqld(Buf_fetch_normal::get(buf_block_t*&)+0x170) [0x5580f2ceec20]
/usr/sbin/mysqld(Buf_fetch<Buf_fetch_normal>::single_page()+0x59) [0x5580f2ceed09]
/usr/sbin/mysqld(buf_page_get_gen(page_id_t const&, page_size_t const&, unsigned long, buf_block_t*, Page_fetch, ut::Location, mtr_t*, bool)+0x1fa) [0x5580f2cf02ea]
/usr/sbin/mysqld(Double_write::get(mtr_t*)+0x56) [0x5580f2cf3c56]
/usr/sbin/mysqld(Double_write::init_v1(unsigned int&, unsigned int&)+0x11b) [0x5580f2cf8c1b]
/usr/sbin/mysqld(dblwr::v1::init()+0x1b) [0x5580f2cf8e2b]
/usr/sbin/mysqld(srv_start(bool)+0x1471) [0x5580f2c166a1]
/usr/sbin/mysqld(+0x2349496) [0x5580f2a1d496]
/usr/sbin/mysqld(dd::bootstrap::DDSE_dict_init(THD*, dict_init_mode_t, unsigned int)+0x9e) [0x5580f27564ae]
/usr/sbin/mysqld(dd::upgrade_57::do_pre_checks_and_initialize_dd(THD*)+0x1a9) [0x5580f29abf89]
/usr/sbin/mysqld(+0x1240896) [0x5580f1914896]
/usr/sbin/mysqld(+0x289d0fd) [0x5580f2f710fd]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x8609) [0x7f94a20cb609]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x43) [0x7f94a1c9c133]
Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (0): is an invalid pointer
Connection ID (thread ID): 1
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.
我认为问题最初是由硬盘已满引起的。我尝试恢复服务器的旧备份，但我拥有的最旧的备份似乎已经存在问题。
我完全陷入困境，没有解决方案。我现在可以尝试什么？
答案1
在您的 my.cnf [mysqld] 部分中您需要一行
thread_cache_size=64
如果该部分中不存在该行，请添加到 [mysqld] 部分。
我们将竭诚为您服务。