Re: postmaster.pid

I validate my pid by examining /proc/pid , something as simple as

if [ -d `cat postmaster.pid` ]
then
echo postmaster is running
else
echo postmaster is not running
fi

Tom Lane wrote:

>Kevin Brown <kevin(at)sysexperts(dot)com> writes:
>
>
>>Tom Lane wrote:
>>
>>
>>>Yeah, if you search the archives you will find previous discussions of
>>>how the check for a pre-existing postmaster could be made more resistant
>>>to false matches. It seems to be a hard problem to solve in a way
>>>that's both portable and 100% safe (while false positives are annoying,
>>>false negatives are completely not acceptable). AFAIR all the
>>>alternative methods that we've heard about have their own downsides.
>>>
>>>
>
>
>
>>I assume one of those alternatives was for the postmaster to open and
>>lock a predefined file in $PGDATA (say, postmaster.lock) using fcntl
>>or flock style locking?
>>
>>
>
>Yes, that was discussed. I think the primary objection was that it's
>very non-robust if the $PGDATA directory is mounted via NFS. (Quite
>a few of us think that if you run a database over NFS, you deserve to
>lose ;-( ... but there seem to be more than a few people out there doing
>it anyway.)
>
>Also, the fact that you even had to mention two different ways of doing
>it is prima facie evidence that there are portability issues...
>
> regards, tom lane
>
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