规格：8 GB 内存 / 4 vCPU / 25 GB ssd
Ubuntu 20.04
我的网站最近遭受了 DDoS 攻击，连续 4 天出现 CPU 使用率高的错误，网站无法加载，我使用 top -c 查看了一下，显示 CPU 使用率为 200%。我尝试了 SQL tuner，但没有看到任何显著的差异，我的网站无法加载
MySQL 调谐器：
>> MySQLTuner 1.8.5 - Major Hayden <[email protected]>
>> Bug reports, feature requests, and downloads at http://mysqltuner.pl/
>> Run with '--help' for additional options and output filtering
[--] Skipped version check for MySQLTuner script
[OK] Logged in using credentials from Debian maintenance account.
[OK] Currently running supported MySQL version 8.0.27-0ubuntu0.20.04.1
[OK] Operating on 64-bit architecture
-------- Log file Recommendations ------------------------------------------------------------------
[OK] Log file /var/log/mysql/error.log exists
[--] Log file: /var/log/mysql/error.log(108K)
[OK] Log file /var/log/mysql/error.log is not empty
[OK] Log file /var/log/mysql/error.log is smaller than 32 Mb
[OK] Log file /var/log/mysql/error.log is readable.
[!!] /var/log/mysql/error.log contains 649 warning(s).
[!!] /var/log/mysql/error.log contains 13 error(s).
[--] 46 start(s) detected in /var/log/mysql/error.log
[--] 1) 2021-11-13T12:29:09.246704Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.27-0ubuntu0.20.04.1' socket: '/var/run/mysqld/mysqld.sock' port: 3306 (Ubuntu).
[--] 2) 2021-11-13T12:29:09.246582Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '127.0.0.1' port: 33060, socket: /var/run/mysqld/mysqlx.sock
[--] 3) 2021-11-13T12:27:00.187056Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.27-0ubuntu0.20.04.1' socket: '/var/run/mysqld/mysqld.sock' port: 3306 (Ubuntu).
[--] 4) 2021-11-13T12:27:00.187031Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '127.0.0.1' port: 33060, socket: /var/run/mysqld/mysqlx.sock
[--] 5) 2021-11-13T12:13:39.810528Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.27-0ubuntu0.20.04.1' socket: '/var/run/mysqld/mysqld.sock' port: 3306 (Ubuntu).
[--] 6) 2021-11-13T12:13:39.810486Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '127.0.0.1' port: 33060, socket: /var/run/mysqld/mysqlx.sock
[--] 7) 2021-11-13T12:03:24.613973Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.27-0ubuntu0.20.04.1' socket: '/var/run/mysqld/mysqld.sock' port: 3306 (Ubuntu).
[--] 8) 2021-11-13T12:03:24.613816Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '127.0.0.1' port: 33060, socket: /var/run/mysqld/mysqlx.sock
[--] 9) 2021-11-13T12:01:03.461232Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '127.0.0.1' port: 33060, socket: /var/run/mysqld/mysqlx.sock
[--] 10) 2021-11-13T12:01:03.460896Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.27-0ubuntu0.20.04.1' socket: '/var/run/mysqld/mysqld.sock' port: 3306 (Ubuntu).
[--] 28 shutdown(s) detected in /var/log/mysql/error.log
[--] 1) 2021-11-13T12:29:07.716280Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.27-0ubuntu0.20.04.1) (Ubuntu).
[--] 2) 2021-11-13T12:26:58.372900Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.27-0ubuntu0.20.04.1) (Ubuntu).
[--] 3) 2021-11-13T12:13:38.455249Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.27-0ubuntu0.20.04.1) (Ubuntu).
[--] 4) 2021-11-13T12:13:35.420337Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.27-0ubuntu0.20.04.1) (Ubuntu).
[--] 5) 2021-11-13T12:13:32.532833Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.27-0ubuntu0.20.04.1) (Ubuntu).
[--] 6) 2021-11-13T12:13:29.484351Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.27-0ubuntu0.20.04.1) (Ubuntu).
[--] 7) 2021-11-13T12:13:26.096897Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.27-0ubuntu0.20.04.1) (Ubuntu).
[--] 8) 2021-11-13T12:13:22.906304Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.27-0ubuntu0.20.04.1) (Ubuntu).
[--] 9) 2021-11-13T12:03:23.022603Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.27-0ubuntu0.20.04.1) (Ubuntu).
[--] 10) 2021-11-13T12:01:01.884057Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.27-0ubuntu0.20.04.1) (Ubuntu).
-------- Storage Engine Statistics -----------------------------------------------------------------
[--] Status: +ARCHIVE +BLACKHOLE +CSV -FEDERATED +InnoDB +MEMORY +MRG_MYISAM +MyISAM +PERFORMANCE_SCHEMA
[--] Data in InnoDB tables: 114.8M (Tables: 56)
[OK] Total fragmented tables: 0
-------- Analysis Performance Metrics --------------------------------------------------------------
[--] innodb_stats_on_metadata: OFF
[OK] No stat updates during querying INFORMATION_SCHEMA.
-------- Security Recommendations ------------------------------------------------------------------
[--] Skipped due to unsupported feature for MySQL 8
-------- CVE Security Recommendations --------------------------------------------------------------
[--] Skipped due to --cvefile option undefined
-------- Performance Metrics -----------------------------------------------------------------------
[--] Up for: 13m 19s (1M q [1K qps], 12K conn, TX: 7G, RX: 136M)
[--] Reads / Writes: 99% / 1%
[--] Binary logging is enabled (GTID MODE: OFF)
[--] Physical Memory : 7.8G
[--] Max MySQL memory : 9.8G
[--] Other process memory: 0B
[--] Total buffers: 288.0M global + 97.6M per thread (100 max threads)
[--] P_S Max memory usage: 72B
[--] Galera GCache Max memory usage: 0B
[!!] Maximum reached memory usage: 9.9G (127.46% of installed RAM)
[!!] Maximum possible memory usage: 9.8G (126.23% of installed RAM)
[!!] Overall possible memory usage with other process exceeded memory
[OK] Slow queries: 0% (15/1M)
[!!] Highest connection usage: 100% (101/100)
[OK] Aborted connections: 0.00% (0/12875)
[!!] name resolution is active : a reverse name resolution is made for each new connection and can reduce performance
[--] Query cache have been removed in MySQL 8
[OK] Sorts requiring temporary tables: 0% (0 temp sorts / 50K sorts)
[OK] No joins without indexes
[OK] Temporary tables created on disk: 0% (0 on disk / 12K total)
[OK] Thread cache hit rate: 89% (1K created / 12K connections)
[OK] Table cache hit rate: 99% (3M hits / 3M requests)
[OK] table_definition_cache(2000) is upper than number of tables(382)
[OK] Open file limit used: 0% (3/10K)
[OK] Table locks acquired immediately: 100% (4 immediate / 4 locks)
[OK] Binlog cache memory access: 100.00% (7 Memory / 7 Total)
-------- Performance schema ------------------------------------------------------------------------
[--] Memory used by P_S: 72B
[--] Sys schema is installed.
-------- ThreadPool Metrics ------------------------------------------------------------------------
[--] ThreadPool stat is disabled.
-------- MyISAM Metrics ----------------------------------------------------------------------------
[--] MyISAM Metrics are disabled on last MySQL versions.
-------- InnoDB Metrics ----------------------------------------------------------------------------
[--] InnoDB is enabled.
[--] InnoDB Thread Concurrency: 0
[OK] InnoDB File per table is activated
[OK] InnoDB buffer pool / data size: 128.0M/114.8M
[!!] Ratio InnoDB log file size / InnoDB Buffer pool size (75 %): 48.0M * 2/128.0M should be equal to 25%
[OK] InnoDB buffer pool instances: 1
[--] Number of InnoDB Buffer Pool Chunk : 1 for 1 Buffer Pool Instance(s)
[OK] Innodb_buffer_pool_size aligned with Innodb_buffer_pool_chunk_size & Innodb_buffer_pool_instances
[OK] InnoDB Read buffer efficiency: 100.00% (58007737 hits/ 58009344 total)
[!!] InnoDB Write Log efficiency: 89.57% (799 hits/ 892 total)
[OK] InnoDB log waits: 0.00% (0 waits / 93 writes)
-------- Aria Metrics ------------------------------------------------------------------------------
[--] Aria Storage Engine not available.
-------- TokuDB Metrics ----------------------------------------------------------------------------
[--] TokuDB is disabled.
-------- XtraDB Metrics ----------------------------------------------------------------------------
[--] XtraDB is disabled.
-------- Galera Metrics ----------------------------------------------------------------------------
[--] Galera is disabled.
-------- Replication Metrics -----------------------------------------------------------------------
[--] Galera Synchronous replication: NO
[--] No replication slave(s) for this server.
[--] Binlog format: ROW
[--] XA support enabled: ON
[--] Semi synchronous replication Master: Not Activated
[--] Semi synchronous replication Slave: Not Activated
[--] This is a standalone server
-------- Recommendations ---------------------------------------------------------------------------
General recommendations:
Check warning line(s) in /var/log/mysql/error.log file
Check error line(s) in /var/log/mysql/error.log file
MySQL was started within the last 24 hours - recommendations may be inaccurate
Reduce your overall MySQL memory footprint for system stability
Dedicate this server to your database for highest performance.
Reduce or eliminate persistent connections to reduce connection usage
Configure your accounts with ip or subnets only, then update your configuration with skip-name-resolve=1
Before changing innodb_log_file_size and/or innodb_log_files_in_group read this:
Variables to adjust:
*** MySQL's maximum memory usage is dangerously high ***
*** Add RAM before increasing MySQL buffer variables ***
max_connections (> 100)
wait_timeout (< 30)
interactive_timeout (< 28800)
innodb_log_file_size should be (=16M) if possible, so InnoDB total log files size equals to 25% of buffer pool size.
答案1
临时解决方案：更改innodb_buffer_pool_size为 1G。要获得更永久的解决方案，请找出哪些查询速度慢，然后在 stackoverflow.com 上询问