Mysql
MySQL 5.7 間歇性最大連接數錯誤
我在使用 MySQL 5.7 時遇到“連接過多”問題，導致服務崩潰。max_connections 系統變數設置為 1000，平均有 +/- 250 個會話/執行緒，因此達到最大連接數很奇怪。該問題主要出現在某些工作日晚上的晚上 10 點到 11 點之間。
該機器是具有 32 Gb RAM 和雙 Xeon CPU 的 Windows 2008 R2 Enterprise Server。以下是更多環境資訊：
Variable | Max Connection Memory ------------------------------------------------- join_buffer_size | 250.00 MB read_buffer_size | 62.50 MB read_rnd_buffer_size | 250.00 MB sort_buffer_size | 250.00 MB max_connections = 1000 | 812.50 MB Timeouts | VALUE ------------------------------------------- connect_timeout | 10 delayed_insert_timeout | 300 have_statement_timeout | YES innodb_flush_log_at_timeout | 1 innodb_lock_wait_timeout | 50 innodb_rollback_on_timeout | OFF interactive_timeout | 28800 lock_wait_timeout | 31536000 net_read_timeout | 30 net_write_timeout | 60 rpl_stop_slave_timeout | 31536000 slave_net_timeout | 60 wait_timeout | 28800 ------------------------------------------- max_allowed_packet | 33554432 slave_max_allowed_packet | 1073741824這是我的範例日誌文件：
Aborted connection 27933 to db: 'wms_mysql' user: 'mysql' host: 'eifprdrds01.domain.com' (Got an error reading communication packets) Aborted connection 26736 to db: 'wms_mysql' user: 'mysql' host: 'eifprdrds01.domain.com' (Got an error reading communication packets) Aborted connection 27200 to db: 'wms_mysql' user: 'mysql' host: 'eifprdrds01.domain.com' (Got an error reading communication packets) Aborted connection 27356 to db: 'wms_mysql' user: 'mysql' host: 'eifprdrds01.domain.com' (Got an error reading communication packets) Aborted connection 29119 to db: 'wms_mysql' user: 'mysql' host: 'pc286.domain.com' (Got an error reading communication packets) Aborted connection 16274 to db: 'wms_mysql' user: 'mysql' host: 'pc828.domain.com' (Got timeout reading communication packets) Aborted connection 24916 to db: 'wms_mysql' user: 'mysql' host: 'pc830.domain.com' (Got an error reading communication packets) Aborted connection 19357 to db: 'wms_mysql' user: 'mysql' host: 'pc830.domain.com' (Got an error reading communication packets) Aborted connection 19343 to db: 'wms_mysql' user: 'mysql' host: 'pc830.domain.com' (Got an error reading communication packets)以下是一些額外的環境參數（全域狀態）：
Variable_name | Value Aborted_clients | 579 Aborted_connects | 1 Binlog_cache_disk_use | 0 Binlog_cache_use | 0 Binlog_stmt_cache_disk_use | 0 Binlog_stmt_cache_use | 0 Bytes_received | 112705860256 Bytes_sent | 1320858513743 Com_admin_commands | 6343 Com_assign_to_keycache | 0 Com_alter_db | 0 Com_alter_db_upgrade | 0 Com_alter_event | 0 Com_alter_function | 0 Com_alter_instance | 0 Com_alter_procedure | 0 Com_alter_server | 0 Com_alter_table | 0 Com_alter_tablespace | 0 Com_alter_user | 0 Com_analyze | 0 Com_begin | 368010 Com_binlog | 0 Com_call_procedure | 0 Com_change_db | 14 Com_change_master | 0 Com_change_repl_filter | 0 Com_check | 0 Com_checksum | 0 Com_commit | 367880 Com_create_db | 0 Com_create_event | 0 Com_create_function | 0 Com_create_index | 0 Com_create_procedure | 0 Com_create_server | 0 Com_create_table | 0 Com_create_trigger | 0 Com_create_udf | 0 Com_create_user | 0 Com_create_view | 0 Com_dealloc_sql | 0 Com_delete | 1899441 Com_delete_multi | 0 Com_do | 0 Com_drop_db | 0 Com_drop_event | 0 Com_drop_function | 0 Com_drop_index | 0 Com_drop_procedure | 0 Com_drop_server | 0 Com_drop_table | 0 Com_drop_trigger | 0 Com_drop_user | 0 Com_drop_view | 0 Com_empty_query | 0 Com_execute_sql | 0 Com_explain_other | 0 Com_flush | 0 Com_get_diagnostics | 0 Com_grant | 0 Com_ha_close | 0 Com_ha_open | 0 Com_ha_read | 0 Com_help | 0 Com_insert | 5932889 Com_insert_select | 0 Com_install_plugin | 0 Com_kill | 1 Com_load | 0 Com_lock_tables | 0 Com_optimize | 0 Com_preload_keys | 0 Com_prepare_sql | 0 Com_purge | 0 Com_purge_before_date | 0 Com_release_savepoint | 0 Com_rename_table | 0 Com_rename_user | 0 Com_repair | 0 Com_replace | 0 Com_replace_select | 0 Com_reset | 0 Com_resignal | 0 Com_revoke | 0 Com_revoke_all | 0 Com_rollback | 107 Com_rollback_to_savepoint | 0 Com_savepoint | 0 Com_select | 305377361 Com_set_option | 412902 Com_signal | 0 Com_show_binlog_events | 0 Com_show_binlogs | 0 Com_show_charsets | 9 Com_show_collations | 9 Com_show_create_db | 0 Com_show_create_event | 0 Com_show_create_func | 0 Com_show_create_proc | 0 Com_show_create_table | 0 Com_show_create_trigger | 0 Com_show_databases | 20 Com_show_engine_logs | 0 Com_show_engine_mutex | 0 Com_show_engine_status | 0 Com_show_events | 0 Com_show_errors | 0 Com_show_fields | 33672455 Com_show_function_code | 0 Com_show_function_status | 8 Com_show_grants | 2 Com_show_keys | 34409046 Com_show_master_status | 0 Com_show_open_tables | 0 Com_show_plugins | 19 Com_show_privileges | 0 Com_show_procedure_code | 0 Com_show_procedure_status | 8 Com_show_processlist | 2 Com_show_profile | 0 Com_show_profiles | 0 Com_show_relaylog_events | 0 Com_show_slave_hosts | 0 Com_show_slave_status | 6 Com_show_status | 337719 Com_show_storage_engines | 9 Com_show_table_status | 0 Com_show_tables | 11 Com_show_triggers | 634 Com_show_variables | 221 Com_show_warnings | 0 Com_show_create_user | 0 Com_shutdown | 0 Com_slave_start | 0 Com_slave_stop | 0 Com_group_replication_start | 0 Com_group_replication_stop | 0 Com_stmt_execute | 2 Com_stmt_close | 2 Com_stmt_fetch | 0 Com_stmt_prepare | 2 Com_stmt_reset | 0 Com_stmt_send_long_data | 0 Com_truncate | 0 Com_uninstall_plugin | 0 Com_unlock_tables | 0 Com_update | 3160289 Com_update_multi | 0 Com_xa_commit | 0 Com_xa_end | 0 Com_xa_prepare | 0 Com_xa_recover | 0 Com_xa_rollback | 0 Com_xa_start | 0 Com_stmt_reprepare | 0 Compression | OFF Connection_errors_accept | 0 Connection_errors_internal | 0 Connection_errors_max_connections | 94 Connection_errors_peer_address | 0 Connection_errors_select | 0 Connection_errors_tcpwrap | 0 Connections | 412961 Created_tmp_disk_tables | 34412942 Created_tmp_files | 53367 Created_tmp_tables | 71692427 Delayed_errors | 0 Delayed_insert_threads | 0 Delayed_writes | 0 Flush_commands | 1 Handler_commit | 315946909 Handler_delete | 5540520 Handler_discover | 0 Handler_external_lock | 688867588 Handler_mrr_init | 0 Handler_prepare | 0 Handler_read_first | 34976935 Handler_read_key | 2188865194 Handler_read_last | 17485 Handler_read_next | 54290082542 Handler_read_prev | 19085786 Handler_read_rnd | 1186807611 Handler_read_rnd_next | 2955796362 Handler_rollback | 148 Handler_savepoint | 0 Handler_savepoint_rollback | 0 Handler_update | 428611514 Handler_write | 646923649 Innodb_buffer_pool_dump_status | Dumping of buffer pool not started Innodb_buffer_pool_load_status | Buffer pool(s) load completed at 181219 19:56:57 Innodb_buffer_pool_resize_status | Innodb_buffer_pool_pages_data | 966720 Innodb_buffer_pool_bytes_data | 2953838592 Innodb_buffer_pool_pages_dirty | 0 Innodb_buffer_pool_bytes_dirty | 0 Innodb_buffer_pool_pages_flushed | 5329236 Innodb_buffer_pool_pages_free | 8197 Innodb_buffer_pool_pages_misc | 73659 Innodb_buffer_pool_pages_total | 1048576 Innodb_buffer_pool_read_ahead_rnd | 0 Innodb_buffer_pool_read_ahead | 34382 Innodb_buffer_pool_read_ahead_evicted | 0 Innodb_buffer_pool_read_requests | 3904592079 Innodb_buffer_pool_reads | 747465 Innodb_buffer_pool_wait_free | 0 Innodb_buffer_pool_write_requests | 1045142981 Innodb_data_fsyncs | 1695449 Innodb_data_pending_fsyncs | 0 Innodb_data_pending_reads | 0 Innodb_data_pending_writes | 0 Innodb_data_read | 644895232 Innodb_data_reads | 1088377 Innodb_data_writes | 14566224 Innodb_data_written | 3881918464 Innodb_dblwr_pages_written | 4497979 Innodb_dblwr_writes | 398532 Innodb_log_waits | 0 Innodb_log_write_requests | 22692404 Innodb_log_writes | 8771102 Innodb_os_log_fsyncs | 322535 Innodb_os_log_pending_fsyncs | 0 Innodb_os_log_pending_writes | 0 Innodb_os_log_written | 18935997952 Innodb_page_size | 16384 Innodb_pages_created | 134590 Innodb_pages_read | 1087932 Innodb_pages_written | 5329236 Innodb_row_lock_current_waits | 0 Innodb_row_lock_time | 3466511 Innodb_row_lock_time_avg | 35015 Innodb_row_lock_time_max | 51754 Innodb_row_lock_waits | 99 Innodb_rows_deleted | 5540520 Innodb_rows_inserted | 564189585 Innodb_rows_read | 2017392003 Innodb_rows_updated | 3601631 Innodb_num_open_files | 300 Innodb_truncated_status_writes | 0 Innodb_available_undo_logs | 128 Key_blocks_not_flushed | 0 Key_blocks_unused | 6698 Key_blocks_used | 4 Key_read_requests | 124 Key_reads | 29 Key_write_requests | 0 Key_writes | 0 Last_query_cost | 0 Last_query_partial_plans | 0 Locked_connects | 0 Max_execution_time_exceeded | 0 Max_execution_time_set | 0 Max_execution_time_set_failed | 0 Max_used_connections | 701 Max_used_connections_time | 12/19/2018 23:27 Not_flushed_delayed_rows | 0 Ongoing_anonymous_transaction_count | 0 Open_files | 1 Open_streams | 0 Open_table_definitions | 876 Open_tables | 2000 Opened_files | 57710 Opened_table_definitions | 876 Opened_tables | 24810492 Performance_schema_accounts_lost | 0 Performance_schema_cond_classes_lost | 0 Performance_schema_cond_instances_lost | 0 Performance_schema_digest_lost | 0 Performance_schema_file_classes_lost | 0 Performance_schema_file_handles_lost | 0 Performance_schema_file_instances_lost | 0 Performance_schema_hosts_lost | 0 Performance_schema_index_stat_lost | 0 Performance_schema_locker_lost | 0 Performance_schema_memory_classes_lost | 0 Performance_schema_metadata_lock_lost | 0 Performance_schema_mutex_classes_lost | 0 Performance_schema_mutex_instances_lost | 0 Performance_schema_nested_statement_lost | 0 Performance_schema_prepared_statements_lost | 0 Performance_schema_program_lost | 0 Performance_schema_rwlock_classes_lost | 0 Performance_schema_rwlock_instances_lost | 0 Performance_schema_session_connect_attrs_lost | 0 Performance_schema_socket_classes_lost | 0 Performance_schema_socket_instances_lost | 0 Performance_schema_stage_classes_lost | 0 Performance_schema_statement_classes_lost | 0 Performance_schema_table_handles_lost | 0 Performance_schema_table_instances_lost | 0 Performance_schema_table_lock_stat_lost | 0 Performance_schema_thread_classes_lost | 0 Performance_schema_thread_instances_lost | 0 Performance_schema_users_lost | 0 Prepared_stmt_count | 0 Qcache_free_blocks | 0 Qcache_free_memory | 0 Qcache_hits | 0 Qcache_inserts | 0 Qcache_lowmem_prunes | 0 Qcache_not_cached | 0 Qcache_queries_in_cache | 0 Qcache_total_blocks | 0 Queries | 386369511 Questions | 386351756 Select_full_join | 8242 Select_full_range_join | 97092 Select_range | 57964836 Select_range_check | 4 Select_scan | 69826287 Slave_heartbeat_period | 0 Slave_last_heartbeat | Slave_open_temp_tables | 0 Slave_received_heartbeats | 0 Slave_retried_transactions | 0 Slave_running | OFF Slow_launch_threads | 0 Slow_queries | 44 Sort_merge_passes | 34863 Sort_range | 1764316 Sort_rows | 299335094 Sort_scan | 2888984 Ssl_accept_renegotiates | 0 Ssl_accepts | 0 Ssl_callback_cache_hits | 0 Ssl_cipher | Ssl_cipher_list | Ssl_client_connects | 0 Ssl_connect_renegotiates | 0 Ssl_ctx_verify_depth | 0 Ssl_ctx_verify_mode | 0 Ssl_default_timeout | 0 Ssl_finished_accepts | 0 Ssl_finished_connects | 0 Ssl_server_not_after | Ssl_server_not_before | Ssl_session_cache_hits | 0 Ssl_session_cache_misses | 0 Ssl_session_cache_mode | NONE Ssl_session_cache_overflows | 0 Ssl_session_cache_size | 0 Ssl_session_cache_timeouts | 0 Ssl_sessions_reused | 0 Ssl_used_session_cache_entries | 0 Ssl_verify_depth | 0 Ssl_verify_mode | 0 Ssl_version | Table_locks_immediate | 67608 Table_locks_waited | 0 Table_open_cache_hits | 386002409 Table_open_cache_misses | 24810492 Table_open_cache_overflows | 24808485 Tc_log_max_pages_used | 0 Tc_log_page_size | 0 Tc_log_page_waits | 0 Threads_cached | 8 Threads_connected | 10 Threads_created | 1388 Threads_running | 1 Uptime | 1018391 Uptime_since_flush_status | 1018391我對正在發生的事情有些茫然。任何建議都會非常有用！
由於連接不會自行斷開，因此請更改全域
wait_timeout. 這將間接減少空閒執行緒的數量和對max_connections.
為您的 my.ini 考慮的建議
$$ mysqld $$部分
join_buffer_size=256K # from 250M to reduce RAM request read_buffer_size=128K # from 62.50M to reduce RAM request read_rnd_buffer_size=256K # from 250M to reduce RAM request sort_buffer_size=2M # from 250M to reduce RAM request前 4 個是每個連接的 RAM 請求，並且您目前的配置對於它們中的大多數是 100X 預設值，並導致伺服器超出可用 RAM。您可以在 MySQL 的錯誤日誌中檢測到這一點。
如需其他建議，請查看我的個人資料、網路個人資料以獲取聯繫資訊並通過 Skype 聯繫。