最近一台核心库备库完成恢复后打开slave,导致主库传送binlog,瞬间占满网络,触发故障。
为了做一些限制, 给mysql在发送binlog的函数(mysql_binlog_send)里每隔一段时间sleep一次, 增加了两个参数:
master_send_count 每读master_send_count次事件,sleep一次
master_send_sleep 每次sleep的时间为master_send_sleep ,单位为毫秒ms
以下统计数据,每1秒统计一次。
1.不受限制
set global master_send_count = 0;
set global master_send_sleep = 0;
2.
set global master_send_count = 10;
set global master_send_sleep = 100;
3.
set global master_send_count = 10;
set global master_send_sleep = 200;
4.
set global master_send_count = 1;
set global master_send_sleep = 15;
5.
set global master_send_count = 1;
set global master_send_sleep = 50;
测试的过程中,发现时不时的网卡发送数据彪的很高,暂不清楚原因,似乎mysql本身会做缓存。
Patch 很简单,基于5.1.48
Index: sql/sql_repl.cc =================================================================== --- sql/sql_repl.cc (revision 2487) +++ sql/sql_repl.cc (working copy) @@ -360,6 +360,8 @@DBUG_ENTER("mysql_binlog_send");DBUG_PRINT("enter",("log_ident: '%s' pos: %ld", log_ident, (long) pos));+ ulong read_count=0; + bzero((char*) &log,sizeof(log));#ifndef DBUG_OFF @@ -541,11 +543,18 @@/* seek to the requested position, to start the requested dump */my_b_seek(&log, pos); // Seek will done on next read - + while (!net->error && net->vio != 0 && !thd->killed){while (!(error = Log_event::read_log_event(&log, packet, log_lock))){ + if (master_send_count != 0 && + master_send_sleep !=0 && + ++read_count>master_send_count) { + my_sleep(master_send_sleep); + read_count=0; + } +#ifndef DBUG_OFFif (max_binlog_dump_events && !left_events--){ Index: sql/mysqld.cc =================================================================== --- sql/mysqld.cc (revision 2487) +++ sql/mysqld.cc (working copy) @@ -540,6 +540,9 @@ulong binlog_cache_use= 0, binlog_cache_disk_use= 0;ulong max_connections, max_connect_errors;uint max_user_connections= 0; +ulong master_send_count = 0; +ulong master_send_sleep = 0; +/**Limit of the total number of prepared statements in the server.Is necessary to protect the server against out-of-memory attacks. @@ -5737,7 +5740,9 @@OPT_SLOW_QUERY_LOG_FILE,OPT_IGNORE_BUILTIN_INNODB,OPT_BINLOG_DIRECT_NON_TRANS_UPDATE, - OPT_DEFAULT_CHARACTER_SET_OLD + OPT_DEFAULT_CHARACTER_SET_OLD, + OPT_MASTER_SEND_COUNT, + OPT_MASTER_SEND_SLEEP};@@ -7128,6 +7133,14 @@"t_innodb; otherwise, slaves may diverge from the master.",(uchar**) &global_system_variables.binlog_direct_non_trans_update, (uchar**) &max_system_variables.binlog_direct_non_trans_update, 0, GET_BOOL, NO_ARG, 0,0, 0, 0, 0, 0}, + {"master_send_count", OPT_MASTER_SEND_COUNT, + "every master_send_count binlog send ,will sleep for a while", + (uchar**) &master_send_count, (uchar**) &master_send_count, 0, GET_ULONG, + REQUIRED_ARG, 0, 0, ULONG_MAX, 0, 1, 0}, + {"master_send_sleep", OPT_MASTER_SEND_SLEEP, + "every master_send_count binlog send ,will sleep master_send_sleep ms", + (uchar**) &master_send_sleep, (uchar**) &master_send_sleep, 0, GET_ULONG, + REQUIRED_ARG, 0, 0, ULONG_MAX, 0, 1, 0},{0, 0, 0, 0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0}};Index: sql/mysql_priv.h =================================================================== --- sql/mysql_priv.h (revision 2487) +++ sql/mysql_priv.h (working copy) @@ -81,6 +81,9 @@/* increment query_id and return it. */inline query_id_t next_query_id() { return global_query_id++; }+extern ulong master_send_count; +extern ulong master_send_sleep; +/* useful constants */extern MYSQL_PLUGIN_IMPORT const key_map key_map_empty;extern MYSQL_PLUGIN_IMPORT key_map key_map_full; /* Should be threaded as const */ Index: sql/set_var.cc =================================================================== --- sql/set_var.cc (revision 2487) +++ sql/set_var.cc (working copy) @@ -436,6 +436,8 @@&SV::myisam_stats_method,&myisam_stats_method_typelib,NULL); +static sys_var_long_ptr Sys_master_send_count(&vars, "master_send_count", &master_send_count); +static sys_var_long_ptr Sys_master_send_sleep(&vars, "master_send_sleep", &master_send_sleep);#ifdef __NT__/* purecov: begin inspected */