Re: FATAL: lock file "postmaster.pid" already exists

[deepak <deepak.pn@xxxxxxxxx>]

On Tue, May 8, 2012 at 3:09 AM, Alban Hertroys <haramrae@xxxxxxxxx> wrote:

On 8 May 2012, at 24:34, deepak wrote:

> Hi,
>
> On Windows 2008, sometimes the server fails to start due to an existing "postmaster.pid' file.
>
> I tried rebooting a few times and even force shutting down the server, and it started up fine.
> It seems to be a race-condition of sorts in the code that detects whether the process with PID
> in the file is running or not.

No, it means that postgres wasn't shut down properly when Windows shut down. Removing the pid-file is one of the last things the shut-down procedure does. The file is used to prevent 2 instances of the same server running on the same data-directory.

If it's a race-condition, it's probably one in Microsoft's shutdown code. I've seen similar problems with Outlook mailboxes on a network directory; Windows unmounts the remote file-systems before Outlook finished updating its files under that mount point, so Outlook throws an error message and Windows doesn't shut down because of that.

I don't suppose that pid-file is on a remote file-system?

No, it's local.
 

> Does any one have this same problem?  Any way to fix it besides removing the PID file
> manually each time the server complains about this?

You could probably script removal of the pid file if its creation date is before the time the system started booting up.

Thanks, it looks like the code already seems to overwrite an old pid file if no other process is using it (if I understand the code correctly, it just echoes a byte onto a pipe to detect this).

Still, I can't see under what conditions this occurs, but I have seen it happen a couple of times, just that I don't know how to predictably reproduce the problem.

--
Deepak