mysql master thread 工作内容
伪代码：
void master_thread(){
goto loop;
loop://主循环begin
for(int i=0;i<10;i++){
thread_sleep(1); //休眠1秒
do log_buffer flush to disk; //将日志缓冲刷新到磁盘文件
if (last_one_second_io < 5%*innodb_io_capacity)//如果前一秒的io操作次数小于(5%的磁盘io吞吐量参数innodb_io_capacity)，合并(5%的磁盘io吞吐量参数)个插入缓冲inser_buffer
do merge 5%*innodb_io_capacity insert_buffer;
if (buf_get_modified_ratio_pct > innodb_max_dirty_pages_pct)//如果当前缓冲区的脏页比例超过配置文件innodb_max_dirty_pages_pct参数值,将innodb_io_capacity个脏页刷新到磁盘文件
do buffer_pool (100%*innodb_io_capacity) dirty_page flush to disk;
else enable adaptive flush
do buffer pool flush desired amount dirty page //???
if (no user activity)
goto background loop;
}
if (last_ten_second_io < innodb_io_capacity) //前10秒的io操作次数小于innodb_io_capacity（就是前面for循环）
do buffer_pool 100%*innodb_io_capacity dirty_page flush to disk; //将innodb_io_capacity个脏页刷新到磁盘文件
do merge at most 5%*innodb_io_capacity insert_buffer; //合并最多5%*innodb_io_capacity个插入缓冲inser_buffer
do log_buffer flush to disk; //将日志缓冲刷新到磁盘文件
do full purge; //删除无用undo页
if (buf_get_modified_ratio_pct > 70%) //如果当前缓冲内存的脏页比例超过70%
do buffer_pool 100%*innodb_io_capacity dirty_page flush to disk; //将innodb_io_capacity个脏页刷新到磁盘文件
else
do buffer_pool 10%*innodb_io_capacity dirty_page flush to disk; //将10%*innodb_io_capacity个脏页刷新到磁盘文件
do fuzzy checkpoint;
goto loop; //主循环end
background loop: //后台循环begin
do full purge; //删除无用undo页
do merge 100%*innodb_io_capacity insert_buffer; //合并innodb_io_capacity个插入缓冲inser_buffer
if (not idle) //如果不是空置的，跳回主循环
goto loop;
else
goto flush loop;//后台循环end 跳到刷新循环
flush loop://刷新循环begin
do buffer_pool 100%*innodb_io_capacity dirty_page flush to disk; //将innodb_io_capacity个脏页刷新到磁盘文件
if (buf_get_modified_ratio_pct > innodb_max_dirty_pages_pct) {
goto flush loop;//跳到刷新循环
}
goto suspend loop; //刷新循环end 跳到暂停循环
suspend loop://暂停循环begin
suspend_thread();//开启挂起线程
waiting event; //等待事件触发
goto loop;//暂停循环end 跳到主循环
}