Re: backend crash following load command

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Martijn van Oosterhout <kleptog(at)svana(dot)org>
Cc: Merlin Moncure <mmoncure(at)gmail(dot)com>, PgSQL General <pgsql-general(at)postgresql(dot)org>
Subject: Re: backend crash following load command
Date: 2006-11-28 20:44:10
Message-ID: 6106.1164746650@sss.pgh.pa.us
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Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:
> Err, that means copy is just rewriting the executable code in the
> backend of the server, while it's running, which understandably
> crashes.

No, I don't think so. "cp -f" means "unlink the old file and create a
new one", as opposed to plain cp which would overwrite in place. Your
theory would explain an observation that plain cp causes a crash while
cp -f does not, but that's the exact opposite of Merlin's report.

The actual situation is that the mmap is referencing a file that's
disappeared from the directory structure (but still exists on disk,
as long as it's held open). dlsym seems unable to cope with that
case. I call that a bug --- it'd be OK for it to return a failure
indication, but not to SIGSEGV.

regards, tom lane

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