On Mon, Aug 27, 2012 at 07:39:35PM -0400, Tom Lane wrote:
> Alvaro Herrera <[email protected]> writes:
> > How about having it sleep for a short while, then try again?
>
> I could get behind that, but I don't think the delay should be more than
> 100ms or so. It's important for the postmaster to acquire the lock (or
> not) pretty quickly, or pg_ctl is going to get confused. If we keep it
> short, we can also dispense with the log spam you were suggesting.
>
> (Actually, I wonder if this type of scenario isn't going to confuse
> pg_ctl already --- it might think the lockfile belongs to the postmaster
> *it* started, not some pre-existing one. Does that matter?)
I took Alvaro's approach of a sleep. The file test was already in a
loop that went 100 times. Basically, if the lock file exists, this
postmaster isn't going to succeed, so I figured there is no reason to
rush in the testing. I gave it 5 tries with one second between
attempts. Either the file is being populated, or it is stale and empty.
I checked pg_ctl and that has a default wait of 60 second, so 5 seconds
to exit out of the postmaster should be fine.
Patch attached.
FYI, I noticed we have a similar 5-second creation time requirement in
pg_ctl:
/*
* The postmaster should create postmaster.pid very soon after being
* started. If it's not there after we've waited 5 or more seconds,
* assume startup failed and give up waiting. (Note this covers both
* cases where the pidfile was never created, and where it was created
* and then removed during postmaster exit.) Also, if there *is* a
* file there but it appears stale, issue a suitable warning and give
* up waiting.
*/
if (i >= 5)
This is for the case where the file has an old pid, rather than it is
empty.
FYI, I fixed the filename problem Tom found.
--
Bruce Momjian <[email protected]> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
new file mode 100644
index 775d71f..0309494
*** a/src/backend/utils/init/miscinit.c
--- b/src/backend/utils/init/miscinit.c
*************** CreateLockFile(const char *filename, boo
*** 766,771 ****
--- 766,793 ----
filename)));
close(fd);
+ if (len == 0)
+ {
+ /*
+ * An empty lock file exits; either is it from another postmaster
+ * that is still starting up, or left from a crash. Check for
+ * five seconds, then if it still empty, it must be from a crash,
+ * so fail and recommend lock file removal.
+ */
+ if (ntries < 5)
+ {
+ sleep(1);
+ continue;
+ }
+ else
+ ereport(FATAL,
+ (errcode(ERRCODE_LOCK_FILE_EXISTS),
+ errmsg("lock file \"%s\" is empty", filename),
+ errhint(
+ "Empty lock file probably left from operating system crash during\n"
+ "database startup; file deletion suggested.")));
+ }
+
buffer[len] = '\0';
encoded_pid = atoi(buffer);
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