Re: [HACKERS] Possible substitute for PostmasterIsAlive polling loops

2011-02-24 Thread Florian Pflug
On Feb24, 2011, at 04:14 , Robert Haas wrote:
 On Wed, Feb 23, 2011 at 4:54 PM, Tom Lane t...@sss.pgh.pa.us wrote:
 IOW, at least on Linux, you *can* arrange to get a signal when your
 parent process dies.
 
 That's pretty cool.
 
 Not sure how ugly it'd be to use this call when available and a time
 delay when not, but it's something to think about.
 
 Yeah.  It may be worth thinking about whether we want to use the
 postmaster-pipe trick someone was proposing.  That might be more
 portable.


FWIW, I did some experiments which this when it was discussion a while ago.

To actually get a signal when the parent dies, I set the FASYNC flag
on the pipe's receiving end's fd. To be able to signal multiple children
using only one pipe, I set the fd's owner to -getgrp() using
fcntl(F_SETOWN). On both linux and OSX 10.6 this caused SIGIO to be sent
to all processes in the process group once sending end of the pipe was
closed.

I don't have access to any other Unixes to test this on, but I since it
works on OSX chances are high that it'll work on FreeBSD also.

best regards,
Florian Pflug


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers


Re: [HACKERS] Possible substitute for PostmasterIsAlive polling loops

2011-02-23 Thread Robert Haas
On Wed, Feb 23, 2011 at 4:54 PM, Tom Lane t...@sss.pgh.pa.us wrote:
 IOW, at least on Linux, you *can* arrange to get a signal when your
 parent process dies.

That's pretty cool.

 Not sure how ugly it'd be to use this call when available and a time
 delay when not, but it's something to think about.

Yeah.  It may be worth thinking about whether we want to use the
postmaster-pipe trick someone was proposing.  That might be more
portable.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers