达梦数据库-后台线程

达梦数据库是主进程-多线程的架构与mysql类似区别于pg的主进程 fork多线程的架构达梦数据库进程-多线程dmserver(达梦数据库主进程)所有后台线程都跑在该进程内查看后台线程SELECT NAME,THREAD_DESC FROMV$THREADSgroup by NAME,THREAD_DESC;SQL select NAME,THREAD_DESC FROM V$THREADS group by NAME,THREAD_DESC; LINEID NAME THREAD_DESC ---------- ------------------- ------------------------------------------------------------------------------------- 1 dm_lpq_thd Local parallel working thread 2 dm_sql_thd User session thread 3 dm_trxbro_thd trx active view broadcast thread 4 dm_trctsk_thd Thread for writing trace information 5 dm_wrkgrp_thd User working thread 6 dm_audit_thd Thread for flush audit logs 7 nlgn_task_thread Thread for writing login information 8 dm_sched_thd Server scheduling thread,used to trigger background checkpoint, time-related triggers 9 dm_lsnr_thd Service listener thread 10 nsvr_console_thread Thread for nsvr console 11 dm_sqllog_thd Thread for writing dmsql dmserver LINEID NAME THREAD_DESC ---------- -------------- ------------------------------------------------------------------ 12 dm_pthd_thd Parallel working thread 13 dm_tskwrk_thd Task Worker Thread for SQL parsing and execution for server itself 14 dm_quit_thd Thread for executing shutdown-normal operation 15 dm_osio_thd os io thread 16 dm_pwr_thd flush PWR log thread 17 dm_rsyswrk_thd Asynchronous archiving thread 18 dm_hio_thd IO thread for HFS to read data pages 19 dm_chkpnt_thd Flush checkpoint thread 20 dm_redolog_thd Redo log thread, used to flush log 21 dm_sql_aux_thd User session auxiliary thread 22 dm_purge_thd Purge thread 22 rows got默认会跑22个后台线程主要线程介绍dm_lsnr_thd(监听线程):端口监听默认 5236接收客户端 TCP 连接请求把会话任务送入任务队列。dm_osio_thd(异步 IO 线程多个)负责异步读、写操作刷脏页读磁盘dm_chkpnt_thd 检查点线程定期触发检查点协调 IO 线程将所有脏数据页写入磁盘触发规则1、调度线程定时触发、2、日志文件写满、3、手动执行CHECKPOINTdm_purge_thd (回滚段清理线程)定期清理事务结束后不再需要的 UNDO 回滚页释放回滚段空间dm_rsyswrk_thd(归档线程组)处理本地归档、将已生成的 REDO 日志打包传输至归档目录或备库非数据库实例常用进程DW守护集群dm_apply_thd日志重做线程备库备库专属线程接收主库同步过来的 ARCHIVE 日志在备库重做事务同步主库数据一主一备默认 1 组多备库多线程并行 APPLYdm_mal_thd MAL通信线程数据守护集群 MAL 消息通道线程主备之间心跳、日志传输、状态交互的通信载体