fork() while connected

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fork() while connected

От:
Michael Meskes <meskes@postgresql.org>
Дата:
I was just asked if there are problems if a program forks() while connected
to the backend. Of course both processes will try to access the DB after the
fork. Is this possible at all? If so does it create timing problems? Or
others? I think I never tried.

Michael
-- 
Michael Meskes
Michael@Fam-Meskes.De
Go SF 49ers! Go Rhein Fire!
Use Debian GNU/Linux! Use PostgreSQL!

Re: fork() while connected

От:
Michael Meskes <meskes@postgresql.org>
Дата:
On Sun, Jan 06, 2002 at 09:24:21AM -0500, Doug McNaught wrote:
> This will definitely not work.  The two processes will stomp all over
> each other.  They'll be sharing one socket and one backend and both
> writing/reading from the socket at random times.

That's exactly what I expected. Thanks.

Michael
-- 
Michael Meskes
Michael@Fam-Meskes.De
Go SF 49ers! Go Rhein Fire!
Use Debian GNU/Linux! Use PostgreSQL!

Re: fork() while connected

От:
Doug McNaught <doug@wireboard.com>
Дата:
Michael Meskes  writes:

> I was just asked if there are problems if a program forks() while connected
> to the backend. Of course both processes will try to access the DB after the
> fork. Is this possible at all? If so does it create timing problems? Or
> others? I think I never tried.

This will definitely not work.  The two processes will stomp all over
each other.  They'll be sharing one socket and one backend and both
writing/reading from the socket at random times.

You can open a second connection in the child (don't close the first
one there, or it'll mess up the parent).  It's probably best to try to
avoid fork()ing with an open connection altogether.

-Doug
-- 
Let us cross over the river, and rest under the shade of the trees.  --T. J. Jackson, 1863
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