Hi, 2018-08-30 15:39 GMT+02:00 Michael Paquier <mich...@paquier.xyz>:
> That's indeed obvious by reading the code. The bgwriter would be > started only once a consistent point has been reached, so the startup > process would have normally already updated the control file to the > consistent point. Something like the attached should take care of the > problem. As the updates of the local copy of minRecoveryPoint strongly > rely on if the startup process is used, I think that we should use > InRecovery for the sanity checks. > > I'd like to also add a TAP test for that, which should be easy enough if > we do sanity checks by looking up at the output of the control file. > I'll try to put more thoughts on that. > > Does it take care of the problem? Yep, with the patch applied bgwriter acts as expected! Breakpoint 1, UpdateControlFile () at xlog.c:4536 4536 INIT_CRC32C(ControlFile->crc); (gdb) bt #0 UpdateControlFile () at xlog.c:4536 #1 0x00005646d071ddb2 in UpdateMinRecoveryPoint (lsn=26341965784, force=0 '\000') at xlog.c:2597 #2 0x00005646d071de65 in XLogFlush (record=26341965784) at xlog.c:2632 #3 0x00005646d09d693a in FlushBuffer (buf=0x7f8e1ca523c0, reln=0x5646d2e86028) at bufmgr.c:2729 #4 0x00005646d09d63d6 in SyncOneBuffer (buf_id=99693, skip_recently_used=1 '\001', wb_context=0x7ffd07757380) at bufmgr.c:2394 #5 0x00005646d09d6172 in BgBufferSync (wb_context=0x7ffd07757380) at bufmgr.c:2270 #6 0x00005646d097c266 in BackgroundWriterMain () at bgwriter.c:279 #7 0x00005646d073b38c in AuxiliaryProcessMain (argc=2, argv=0x7ffd07758840) at bootstrap.c:424 #8 0x00005646d098dc4a in StartChildProcess (type=BgWriterProcess) at postmaster.c:5300 #9 0x00005646d098d672 in sigusr1_handler (postgres_signal_arg=10) at postmaster.c:4999 #10 <signal handler called> #11 0x00007f8e5f5a6ff7 in __GI___select (nfds=5, readfds=0x7ffd07759060, writefds=0x0, exceptfds=0x0, timeout=0x7ffd07758fd0) at ../sysdeps/unix/sysv/linux/select.c:41 #12 0x00005646d09890ca in ServerLoop () at postmaster.c:1685 #13 0x00005646d0988799 in PostmasterMain (argc=17, argv=0x5646d2e53390) at postmaster.c:1329 #14 0x00005646d08d2880 in main (argc=17, argv=0x5646d2e53390) at main.c:228 Regards, -- Alexander Kukushkin
