Thread: HELP < 63 users
Hi all, While testing i found this unexpected limit: There seems to be a hard 63 postmaster.exe backends limit to cygwin. My postgresql.conf mentions: max_connections = 200 shared_buffers = 512 I could not find any pointer to this in the cygwin or postgresql docs about this. Jason Tishler noted this before in a review of why 'make test' (parallel) failed (one year ago). I tested a little: it seems that cygwin cannot spawn more than 63 children procs. This does not seem like a winNT problem. The questions: Is it true that cygwin cannot spawn more the 63 children? Is this known? Does this issue limit postgresql on cygwin to max 63 backends/concurrent connections? Does someone have a good idea to work around this limit? Any previous experience with this? Greetings Joek Hondius
Hi, On Tue, 27 Aug 2002 16:45:49 +0200 "joek hondius" <jhondius@rem.nl> wrote: > Hi all, > While testing i found this unexpected limit: > There seems to be a hard 63 postmaster.exe backends limit to cygwin. (snip) > The questions: > Is it true that cygwin cannot spawn more the 63 children? Yes. > Is this known? Yes. > Does someone have a good idea to work around this limit? Cygwin B20 has no limitation about this(I succeed with 128 connections). But I don't know whether latest PostgreSQL work on Cygwin B20(Probably not). --- Yutaka tanida<yutaka@hi-net.zaq.ne.jp>
Joek,
On Tue, Aug 27, 2002 at 04:45:49PM +0200, joek hondius wrote:
> I could not find any pointer to this in the cygwin or postgresql docs
> about this. Jason Tishler noted this before in a review of why 'make
> test' (parallel) failed (one year ago).
I don't recall the above. Please provide an URL.
Are you referring to the following (from the README)?
1. make check can generate spurious regression test failures due to
overflowing the the listen() backlog queue which generates
connection refused errors. Note that make installcheck does not
have this problem since it runs all tests sequentially instead of in
large concurrent groups.
Jason
>Joek, > >On Tue, Aug 27, 2002 at 04:45:49PM +0200, joek hondius wrote: >> I could not find any pointer to this in the cygwin or postgresql docs >> about this. Jason Tishler noted this before in a review of why 'make >> test' (parallel) failed (one year ago). > >I don't recall the above. Please provide an URL. Somehow i could not find the original postings anymore (they where there 3 weeks ago), but thanks to google's cache: http://www.google.nl/search?q=cache:CXMBRFwDZUwC:postgresql.linux.cz/mhonarc /pgsql-ports/2001-03/msg00128.html+&hl=nl&ie=UTF-8 This is just some part of the discussion however. > >Are you referring to the following (from the README)? > > 1. make check can generate spurious regression test failures due to > overflowing the the listen() backlog queue which generates > connection refused errors. Note that make installcheck does not > have this problem since it runs all tests sequentially instead of in > large concurrent groups. > >Jason Of course i was referring to make check, not test (Ahum..), But this is not a backlog problem. Its seems to me to be a fork() to windows mapping problem. The WaitForObject() winAPI call is limited to 63. So postgreSQL really seems limited to 63 backends on cygwin. :( I'm trying to get 200 concurrent users to work. Joek
Joek, On Thu, Aug 29, 2002 at 12:11:11PM +0200, joek hondius wrote: > >On Tue, Aug 27, 2002 at 04:45:49PM +0200, joek hondius wrote: > >> I could not find any pointer to this in the cygwin or postgresql > >> docs about this. Jason Tishler noted this before in a review of > >> why 'make test' (parallel) failed (one year ago). > > > >I don't recall the above. Please provide an URL. > > Somehow i could not find the original postings anymore (they where > there 3 weeks ago), They recently fell off the end of the PostgreSQL mailing list archives. > but thanks to google's cache: > http://www.google.nl/search?q=cache:CXMBRFwDZUwC:postgresql.linux.cz/mhonarc/pgsql-ports/2001-03/msg00128.html+&hl=nl&ie=UTF-8 The above refers to a bug in libpq. See the following thread for the details: http://www.geocrawler.com/mail/thread.php3?subject=%5BPORTS%5D+Cygwin+PostgreSQL+Regression+Test+Problems+%28Revisited%29&list=104 Specifically, the following: http://www.geocrawler.com/mail/msg.php3?msg_id=5455858&list=104 > >Are you referring to the following (from the README)? > > > > 1. make check can generate spurious regression test failures due to > > overflowing the the listen() backlog queue which generates > > connection refused errors. Note that make installcheck does not > > have this problem since it runs all tests sequentially instead of in > > large concurrent groups. > > But this is not a backlog problem. Understood. > Its seems to me to be a fork() to windows mapping problem. The > WaitForObject() winAPI call is limited to 63. So postgreSQL really > seems limited to 63 backends on cygwin. :( Unfortunately, Cygwin has this limitation. Nevertheless, the fork() issue is not why make check above failed. I was just trying to clear this up for the archives. Jason