Mariadb
MySQL 的最大記憶體使用量非常高
我試圖了解在我的配置中什麼不起作用。
當我執行
[root@server ~]# ./mysqltuner.pl >> MySQLTuner 1.9.8 * Jean-Marie Renouard <jmrenouard@gmail.com> * Major Hayden <major@mhtx.net> >> 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 [!!] Your MySQL version 10.2.43-MariaDB-log is EOL software! Upgrade soon! [OK] Operating on 64-bit architecture -------- Log file Recommendations ------------------------------------------------------------------ [OK] Log file /var/log/mysqld.log exists [--] Log file: /var/log/mysqld.log(1M) [OK] Log file /var/log/mysqld.log is not empty [OK] Log file /var/log/mysqld.log is smaller than 32 Mb [OK] Log file /var/log/mysqld.log is readable. [!!] /var/log/mysqld.log contains 7295 warning(s). [!!] /var/log/mysqld.log contains 2416 error(s). [--] 68 start(s) detected in /var/log/mysqld.log [--] 1) 2022-04-15 15:28:49 139969276774592 [Note] /usr/sbin/mysqld: ready for connections. [--] 2) 2022-04-15 15:01:58 139671548569792 [Note] /usr/sbin/mysqld: ready for connections. [--] 3) 2022-04-15 15:00:37 139816143530176 [Note] /usr/sbin/mysqld: ready for connections. [--] 4) 2022-04-11 15:13:19 140028901791936 [Note] /usr/sbin/mysqld: ready for connections. [--] 5) 2022-03-29 2:44:09 140256877758656 [Note] /usr/sbin/mysqld: ready for connections. [--] 6) 2022-03-22 2:42:21 140486199806144 [Note] /usr/sbin/mysqld: ready for connections. [--] 7) 2022-02-14 2:42:44 139938060060864 [Note] /usr/sbin/mysqld: ready for connections. [--] 8) 2022-02-14 2:42:41 139960106510528 [Note] /usr/sbin/mysqld: ready for connections. [--] 9) 2022-02-09 2:45:31 140350442416320 [Note] /usr/sbin/mysqld: ready for connections. [--] 10) 2022-02-09 2:45:28 139988696365248 [Note] /usr/sbin/mysqld: ready for connections. [--] 49 shutdown(s) detected in /var/log/mysqld.log [--] 1) 2022-04-15 15:28:49 139670594152192 [Note] /usr/sbin/mysqld: Shutdown complete [--] 2) 2022-04-15 15:01:57 139815146489600 [Note] /usr/sbin/mysqld: Shutdown complete [--] 3) 2022-04-15 14:58:06 140027817096960 [Note] /usr/sbin/mysqld: Shutdown complete [--] 4) 2022-04-11 15:12:31 140255785293568 [Note] /usr/sbin/mysqld: Shutdown complete [--] 5) 2022-03-29 2:44:09 140485092288256 [Note] /usr/sbin/mysqld: Shutdown complete [--] 6) 2022-03-22 2:42:20 139937820497664 [Note] /usr/sbin/mysqld: Shutdown complete [--] 7) 2022-02-14 2:42:44 139959094945536 [Note] /usr/sbin/mysqld: Shutdown complete [--] 8) 2022-02-14 2:42:40 140349468514048 [Note] /usr/sbin/mysqld: Shutdown complete [--] 9) 2022-02-09 2:45:31 139987684747008 [Note] /usr/sbin/mysqld: Shutdown complete [--] 10) 2022-02-09 2:45:27 140367091803904 [Note] /usr/sbin/mysqld: Shutdown complete -------- Storage Engine Statistics ----------------------------------------------------------------- [--] Status: +Aria +CSV +InnoDB +MEMORY +MRG_MyISAM +MyISAM +PERFORMANCE_SCHEMA +SEQUENCE [--] Data in InnoDB tables: 3.9G (Tables: 718) [OK] Total fragmented tables: 0 -------- Analysis Performance Metrics -------------------------------------------------------------- [--] innodb_stats_on_metadata: OFF [OK] No stat updates during querying INFORMATION_SCHEMA. -------- Views Metrics ----------------------------------------------------------------------------- -------- Triggers Metrics -------------------------------------------------------------------------- -------- Routines Metrics -------------------------------------------------------------------------- -------- Security Recommendations ------------------------------------------------------------------ [OK] There are no anonymous accounts for any database users [OK] All database users have passwords assigned [!!] There is no basic password file list! -------- CVE Security Recommendations -------------------------------------------------------------- [--] Skipped due to --cvefile option undefined -------- Performance Metrics ----------------------------------------------------------------------- [--] Up for: 30m 9s (233K q [128.918 qps], 1K conn, TX: 1G, RX: 56M) [--] Reads / Writes: 93% / 7% [--] Binary logging is disabled [--] Physical Memory : 7.6G [--] Max MySQL memory : 45.1G [--] Other process memory: 0B [--] Total buffers: 416.0M global + 302.3M per thread (151 max threads) [--] P_S Max memory usage: 93M [--] Galera GCache Max memory usage: 0B [OK] Maximum reached memory usage: 3.4G (45.17% of installed RAM) [!!] Maximum possible memory usage: 45.1G (590.18% of installed RAM) [!!] Overall possible memory usage with other process exceeded memory [OK] Slow queries: 0% (33/233K) [OK] Highest usage of available connections: 6% (10/151) [OK] Aborted connections: 0.14% (2/1476) [!!] CPanel and Flex system skip-name-resolve should be on [OK] Query cache is disabled by default due to mutex contention on multiprocessor machines. [OK] Sorts requiring temporary tables: 0% (0 temp sorts / 40K sorts) [!!] Joins performed without indexes: 559 [!!] Temporary tables created on disk: 87% (28K on disk / 32K total) [OK] Thread cache hit rate: 99% (10 created / 1K connections) [OK] Table cache hit rate: 99% (865 hits / 872 requests) [OK] table_definition_cache(2097152) is upper than number of tables(984) [OK] Open file limit used: 0% (38/40K) [OK] Table locks acquired immediately: 100% (134 immediate / 134 locks) -------- Performance schema ------------------------------------------------------------------------ [--] Performance_schema is activated. [--] Memory used by P_S: 93.6M [--] Sys schema is installed. -------- ThreadPool Metrics ------------------------------------------------------------------------ [--] ThreadPool stat is disabled. -------- MyISAM Metrics ---------------------------------------------------------------------------- [!!] Key buffer used: 18.3% (23.4M used / 128.0M cache) [OK] Key buffer size / total MyISAM indexes: 128.0M/137.0K [OK] Read Key buffer hit rate: 96.6% (716 cached / 24 reads) -------- InnoDB Metrics ---------------------------------------------------------------------------- [--] InnoDB is enabled. [--] InnoDB Thread Concurrency: 0 [OK] InnoDB File per table is activated [!!] InnoDB buffer pool / data size: 128.0M/3.9G [OK] Ratio InnoDB log file size / InnoDB Buffer pool size: 14.0M * 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: 99.63% (202127202 hits/ 202873879 total) [!!] InnoDB Write Log efficiency: 83.74% (66789 hits/ 79762 total) [OK] InnoDB log waits: 0.00% (0 waits / 12973 writes) -------- Aria Metrics ------------------------------------------------------------------------------ [--] Aria Storage Engine is enabled. [OK] Aria pagecache size / total Aria indexes: 128.0M/0B [OK] Aria pagecache hit rate: 98.7% (1M cached / 24K reads) -------- 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: MIXED [--] XA support enabled: ON [--] Semi synchronous replication Master: Not Activated [--] Semi synchronous replication Slave: Not Activated [--] This is a standalone server -------- Recommendations --------------------------------------------------------------------------- General recommendations: You are using n unsupported version for production environments Upgrade as soon as possible to a supported version ! Check warning line(s) in /var/log/mysqld.log file Check error line(s) in /var/log/mysqld.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. name resolution is enabled due to cPanel doesn't support this disabled. We will suggest raising the 'join_buffer_size' until JOINs not using indexes are found. See https://dev.mysql.com/doc/internals/en/join-buffer-size.html (specially the conclusions at the bottom of the page). When making adjustments, make tmp_table_size/max_heap_table_size equal Reduce your SELECT DISTINCT queries which have no LIMIT clause Variables to adjust: *** MySQL's maximum memory usage is dangerously high *** *** Add RAM before increasing MySQL buffer variables *** skip-name-resolve=0 join_buffer_size (> 40.0M, or always use indexes with JOINs) tmp_table_size (> 16M) max_heap_table_size (> 16M) key_buffer_size (~ 24M) innodb_buffer_pool_size (>= 3.9G) if possible.我真的很擔心“MySQL 的最大記憶體使用率非常高”的消息，因為這意味著如果 MySQL 嘗試獲取比 RAM 更多的記憶體，伺服器可能會意外崩潰。
這是我的 my.cnf ：
[root@server ~]# cat /etc/my.cnf # For advice on how to change settings please see # http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html [mysqld] performance-schema=0 # # Remove leading # and set to the amount of RAM for the most important data # cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%. innodb_buffer_pool_size = 128M # # Remove leading # to turn on a very important data integrity option: logging # changes to the binary log between backups. # log_bin # # Remove leading # to set options mainly useful for reporting servers. # The server defaults are faster for transactions and fast SELECTs. # Adjust sizes as needed, experiment to find the optimal values. join_buffer_size = 40M sort_buffer_size = 2M read_buffer_size = 2M read_rnd_buffer_size = 2M datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 log-error=/var/log/mysqld.log # pid-file=/var/run/mysqld/mysqld.pid max_allowed_packet=16M open_files_limit=40000 innodb_file_per_table=1 query_cache_size=0 query_cache_type=0 query_cache_limit=1M tmp_table_size=16M max_heap_table_size=16M performance_schema=ON innodb_log_file_size=14M table_definition_cache=-1 slow_query_log = 1 slow-query_log_file = /var/log/mysql-slow.log long_query_time = 2我試圖改變 join_buffer_size = 40M sort_buffer_size = 2M read_buffer_size = 2M read_rnd_buffer_size = 2M
但它似乎變得更糟。我最初的 my.cnf 是：
[root@server ~]# cat /etc/my.cnf.backup # For advice on how to change settings please see # http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html [mysqld] performance-schema=0 # # Remove leading # and set to the amount of RAM for the most important data # cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%. # innodb_buffer_pool_size = 128M # # Remove leading # to turn on a very important data integrity option: logging # changes to the binary log between backups. # log_bin # # Remove leading # to set options mainly useful for reporting servers. # The server defaults are faster for transactions and fast SELECTs. # Adjust sizes as needed, experiment to find the optimal values. # join_buffer_size = 128M # sort_buffer_size = 2M # read_rnd_buffer_size = 2M datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 log-error=/var/log/mysqld.log # pid-file=/var/run/mysqld/mysqld.pid innodb_buffer_pool_size=122683392 max_allowed_packet=268435456 open_files_limit=40000 innodb_file_per_table=1 query_cache_size=0 query_cache_type=0 query_cache_limit=1M tmp_table_size=16M max_heap_table_size=16M performance_schema=ON innodb_buffer_pool_size=260M innodb_log_file_size=14M table_definition_cache=-1 slow_query_log = 1 slow-query_log_file = /var/log/mysql-slow.log long_query_time = 2任何人都可以看到的任何建議、明顯的錯誤或錯誤配置？
這是一個舊的預設值：
innodb_buffer_pool_size = 128M將設置提高到 以
5G獲得更好的性能。但是，這與您的問題相反。副手，我沒有看到任何“太大”的設置。
max_connections = 151沒關係。因此，該工具必須抱怨“每執行緒 302.3M”。“在磁碟上創建的臨時表”（和其他事情）意味著某些表的索引很差和/或查詢寫得不好。您似乎打開了慢速日誌。用於
pt-query-digest發現哪個查詢是“最差”的。請注意，他們的公式是不完美的。（沒有完美的公式。）不過，該工具還是找到了一些東西。讓我們深入探勘；提供此處要求的資訊：http: //mysql.rjweb.org/doc.php/mysql_analysis#tuning
至於由於記憶體不足而導致的“崩潰”，設置“交換”會導致數據庫變慢而不是崩潰。
我同意 Rick James 的回答，但我想更直接地說明這一點：
**來自 mysqltuner 的“最大記憶體”警告是垃圾。**這是一個不切實際的估計，因為它發生的可能性幾乎為零。
他們計算的記憶體使用情況與有條件分配的緩衝區有關，具體取決於某些查詢行為。並非所有查詢都分配所有這些緩衝區。即使他們確實分配了緩衝區，他們也可能不會分配緩衝區的全部大小。
給定查詢以最大大小分配所有可能緩衝區的機會很小。
此外，即使您有
max_connections=151，在執行的系統中也很典型，並非所有連接都在同時執行查詢。除非您的系統非常繁忙且鎖爭用很糟糕，否則我預計在任何給定時刻執行查詢的執行緒數最多為 10-20。我忽略了來自 MySQL Tuner 等自動調整工具的最大記憶體警告。MySQL Tuner 給出的“最大記憶體”估計值是我管理的每台數據庫伺服器上 RAM 大小的許多倍。
那麼應該如何估計記憶體使用量呢？
通過觀察。
使用或之
mysqld類的工具監控程序的實際記憶體使用情況。理想情況下，您應該有一個持續的監控系統來製作隨時間變化的圖表，這樣您就可以觀察趨勢。top``ps這比依賴 MySQL Tuner 或任何其他估計要準確得多。這些估計沒有考慮您的數據庫流量或活動。