Dear Horiguchi-san, > Thus how about before entering an apply_delay, logrep worker sending a > kind of crafted feedback, which reports commit_data.end_lsn as > flushpos? A little tweak is needed in send_feedback() but seems to > work..
Thanks for replying! I tested your saying but it could not work well... I made PoC based on the latest time-delayed patches [1] for non-streaming case. Apply workers that are delaying applications send begin_data.final_lsn as recvpos and flushpos in send_feedback(). Followings were contents of the feedback message I got, and we could see that recv and flush were overwritten. ``` DEBUG: sending feedback (force 1) to recv 0/1553638, write 0/1553550, flush 0/1553638 CONTEXT: processing remote data for replication origin "pg_16390" during message type "BEGIN" in transaction 730, finished at 0/1553638 ``` In terms of walsender, however, sentPtr seemed to be slightly larger than flushed position on subscriber. ``` (gdb) p MyWalSnd->sentPtr $2 = 22361760 (gdb) p MyWalSnd->flush $3 = 22361656 (gdb) p *MyWalSnd $4 = {pid = 28807, state = WALSNDSTATE_STREAMING, sentPtr = 22361760, needreload = false, write = 22361656, flush = 22361656, apply = 22361424, writeLag = 20020343, flushLag = 20020343, applyLag = 20020343, sync_standby_priority = 0, mutex = 0 '\000', latch = 0x7ff0350cbb94, replyTime = 725113263592095} ``` Therefore I could not shut down the publisher node when applications were delaying. Do you have any opinions about them? ``` $ pg_ctl stop -D data_pub/ waiting for server to shut down............................................................... failed pg_ctl: server does not shut down ``` [1]: https://www.postgresql.org/message-id/tycpr01mb83730a3e21e921335f6efa38ed...@tycpr01mb8373.jpnprd01.prod.outlook.com Best Regards, Hayato Kuroda FUJITSU LIMITED