is there a good reason to print the "database system is ready" message in StartupXLOG() in xact.c? It has a) nothing to do with xlog and b) opens a small race condition: the message gets printed, while it still take some CPU cycles until the postmaster really gets the SIGCHLD signal and sets StartupPID = 0. If you (or rather: an automated test program) try to connect within this timespan, you get a "database is starting up" error, which clearly contradicts the "is ready" message.

I admit this is not a real issue in the common case and only matters in automated testing or some such. But in case this does not break anything... (ereport is used in the reaper, so I guess it's fine to use that in signal handlers). I'm not sure if the message is needed at all in BS_XLOG_BOOTSTRAP mode. Probably it should better say something different.

Patch attached.


*** src/backend/access/transam/xlog.c	2191ee8ca338d74f666b4d3509cc4361c44b4353
--- src/backend/access/transam/xlog.c	e77a26a26ec46d4479563ed7ff5885ea9c21135a
*************** StartupXLOG(void)
*** 5168,5176 ****
  	/* Reload shared-memory state for prepared transactions */
- 	ereport(LOG,
- 			(errmsg("database system is ready")));
  	/* Shut down readFile facility, free space */
  	if (readFile >= 0)
--- 5168,5173 ----
*** src/backend/bootstrap/bootstrap.c	55fd17241f51b6f23131a0d36d5ce583aa7a3488
--- src/backend/bootstrap/bootstrap.c	8a54e88b06acad46c83320ca8fe13caa75ad77b9
*************** BootstrapMain(int argc, char *argv[])
*** 418,423 ****
--- 418,425 ----
+ 			ereport(LOG,
+ 					(errmsg("database system is ready")));
*** src/backend/postmaster/postmaster.c	561d13618e62e95a32b42b2e9305a638edacf24f
--- src/backend/postmaster/postmaster.c	5a567893b0ed78d312a19e7054127dc5b6b69df3
*************** reaper(SIGNAL_ARGS)
*** 2040,2045 ****
--- 2040,2048 ----
  		if (StartupPID != 0 && pid == StartupPID)
  			StartupPID = 0;
+ 			ereport(LOG,
+ 					(errmsg("database system is ready")));
  			/* Note: FATAL exit of startup is treated as catastrophic */
  			if (!EXIT_STATUS_0(exitstatus))
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