最近一臺核心庫備庫完成恢復后打開slave，導致主庫傳送binlog，瞬間占滿網絡，觸發故障。

為了做一些限制， 給mysql在發送binlog的函數(mysql_binlog_send)里每隔一段時間sleep一次， 增加了兩個參數：

master_send_count? 每讀master_send_count次事件，sleep一次

master_send_sleep?? 每次sleep的時間為master_send_sleep ，單位為毫秒ms

以下統計數據，每1秒統計一次。

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;

測試的過程中，發現時不時的網卡發送數據彪的很高，暫不清楚原因，似乎mysql本身會做緩存。

Patch 很簡單，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 */