時(shí)間:2024-02-21 13:55作者:下載吧人氣:20
一、問題
pg_ctl start啟動(dòng)時(shí)報(bào)錯(cuò)退出:pg_ctl:server did not start in time
。超時(shí)時(shí)間是多少?從什么時(shí)候到哪個(gè)階段算超時(shí)?
二、分析:該信息打印位置,從后面代碼段do_start函數(shù)中可以看出
1、pg_ctl start調(diào)用start_postmaster啟動(dòng)PG的主進(jìn)程后,每隔0.1ms檢查一次postmaster.pid文件,是否已寫入ready/standby
2、總共會(huì)檢查600次,即從啟動(dòng)主進(jìn)程后,最多等待60s,如果沒有寫入ready/standby則打印上述日志并退出
3、默認(rèn)等待時(shí)間是60s,如果pg_ctl start -t指定等待時(shí)間,則等待時(shí)間為該指定時(shí)間
三、什么時(shí)候postmaster.pid文件寫入ready/standby
1、如果是主機(jī)不管有沒有設(shè)置hot standby
1)當(dāng)startup進(jìn)程恢復(fù)完成退出時(shí),調(diào)用proc_exit函數(shù)向主進(jìn)程發(fā)送SIGCHLD信號(hào)并退出
2)主進(jìn)程接收到信號(hào)后,signal處理函數(shù)reaper調(diào)用AddToDataDirLockFile向postmaster.pid文件寫入ready
2、如果是備機(jī)即data目錄下有recovery.cnf文件,且設(shè)置了hot standby,在實(shí)際恢復(fù)前沒有到達(dá)一致性位置
1)startup進(jìn)程向主進(jìn)程發(fā)送PMSIGNAL_RECOVERY_STARTED信號(hào),主進(jìn)程調(diào)用信號(hào)處理函數(shù)sigusr1_handler,將pmState=PM_RECOVERY
2)每次讀取下一個(gè)xlog前都會(huì)調(diào)用CheckRecoveryConsistency函數(shù)進(jìn)行一致性檢查:
2.1 進(jìn)入一致性狀態(tài),starup進(jìn)程向主進(jìn)程發(fā)送PMSIGNAL_BEGIN_HOT_STANDBY信號(hào),主進(jìn)程接收到信號(hào)后調(diào)用sigusr1_handler->AddToDataDirLockFile向postmaster.pid文件寫入ready
3、如果是備機(jī)即data目錄下有recovery.cnf文件,且設(shè)置了hot standby,在實(shí)際恢復(fù)前沒有到達(dá)一致性位置
1)startup進(jìn)程向主進(jìn)程發(fā)送PMSIGNAL_RECOVERY_STARTED信號(hào),主進(jìn)程調(diào)用信號(hào)處理函數(shù)sigusr1_handler,將pmState=PM_RECOVERY
2)每次讀取下一個(gè)xlog前都會(huì)調(diào)用CheckRecoveryConsistency函數(shù)進(jìn)行一致性檢查。如果沒有進(jìn)入一致性狀態(tài)
3)本地日志恢復(fù)完成,切換日志源時(shí)同樣調(diào)用CheckRecoveryConsistency函數(shù)進(jìn)行一致性檢查
3.1 進(jìn)入一致性狀態(tài),starup進(jìn)程向主進(jìn)程發(fā)送PMSIGNAL_BEGIN_HOT_STANDBY信號(hào),主進(jìn)程接收到信號(hào)后調(diào)用sigusr1_handler->AddToDataDirLockFile向postmaster.pid文件寫入ready
4、如果是備機(jī)即data目錄下有recovery.cnf文件,且設(shè)置了hot standby,在實(shí)際恢復(fù)前到達(dá)一致性位置
1)startup進(jìn)程向主進(jìn)程發(fā)送PMSIGNAL_RECOVERY_STARTED信號(hào),主進(jìn)程調(diào)用信號(hào)處理函數(shù)sigusr1_handler,將pmState=PM_RECOVERY
2)CheckRecoveryConsistency函數(shù)進(jìn)行一致性檢查,向主進(jìn)程發(fā)送PMSIGNAL_BEGIN_HOT_STANDBY信號(hào),主進(jìn)程接收到信號(hào)后調(diào)用sigusr1_handler->AddToDataDirLockFile向postmaster.pid文件寫入ready
5、如果是備機(jī)即data目錄下有recovery.cnf文件,沒有設(shè)置hot standby
1)startup進(jìn)程向主進(jìn)程發(fā)送PMSIGNAL_RECOVERY_STARTED信號(hào)
2)主進(jìn)程接收到信號(hào)后,向postmaster.將pmState=PM_RECOVERY
四、代碼分析
1、pg_ctl start流程
do_start-> pm_pid = start_postmaster(); if (do_wait){ print_msg(_("waiting for server to start...")); switch (wait_for_postmaster(pm_pid, false)){ case POSTMASTER_READY: print_msg(_(" donen")); print_msg(_("server startedn")); break; case POSTMASTER_STILL_STARTING: print_msg(_(" stopped waitingn")); write_stderr(_("%s: server did not start in timen"), progname); exit(1); break; case POSTMASTER_FAILED: print_msg(_(" stopped waitingn")); write_stderr(_("%s: could not start servern" "Examine the log output.n"), progname); exit(1); break; } }else print_msg(_("server startingn"));
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