Keepalives win32
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From: Magnus Hagander on 30 Jun 2010 10:32 On Wed, Jun 30, 2010 at 16:27, Tom Lane <tgl(a)sss.pgh.pa.us> wrote: > Magnus Hagander <magnus(a)hagander.net> writes: >> Do you have an opinion on the two choices for handling keepalives_idle >> and keepalives_interval? They basically are: > >> 1) When not configured, use system defaults. When only one of the two >> parameters configured, use RFC default for the other one (overwrite >> system default). > >> 2) When not configured, use RFC defaults (overwrite system defaults). >> When only one of the two parameters configured, use RFC default for >> the other one (overwrite system default) > >> 3) When not configured, use system defaults. When only one of the two >> parameters configured, throw error. > > It's hard to argue about this when most of us have no idea what these > "system defaults" are, or whether they really are any different from the > RFC values in the first place, or whether ordinary users know how to > alter them or even find out their values. �Please provide some > background if you want intelligent comments. The system defaults are whatever the user has configured at a machine level (by editing the registry, by hand or by tool (including policies)). I doubt many users have configured them by hand. There may well be tools that do it for them. Anyway, after some checking i realized #3 can't be implemented anyway in the backend, since guc won't let us know early enough. So that's out. Thus, let's go with #2. Which was your suggestion :) -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
From: Bruce Momjian on 30 Jun 2010 10:56 Tom Lane wrote: > Magnus Hagander <magnus(a)hagander.net> writes: > > On Wed, Jun 30, 2010 at 16:27, Tom Lane <tgl(a)sss.pgh.pa.us> wrote: > >> It's hard to argue about this when most of us have no idea what these > >> "system defaults" are, or whether they really are any different from the > >> RFC values in the first place, or whether ordinary users know how to > >> alter them or even find out their values. �Please provide some > >> background if you want intelligent comments. > > > The system defaults are whatever the user has configured at a machine > > level (by editing the registry, by hand or by tool (including > > policies)). I doubt many users have configured them by hand. There may > > well be tools that do it for them. > > But you previously stated that this code was ignoring the registry > values. So doesn't "system defaults" boil down to whatever Windows' > wired-in defaults are? For Magnus, #2 was to use the RFC defaults. The OS defaults might be different for different versions of Windows. We could use the OS defaults for _some_ version of Windows, but I am not sure that is an improvement. I still like #1 because it affects the fewest people, and that option uses the RFC defaults only for unset values when others are set. I still think we can do #3 (error), but we have to add a check in an unrelated place to check for unset values, and the code is likely to be ugly. -- Bruce Momjian <bruce(a)momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + None of us is going to be here forever. + -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
From: "Kevin Grittner" on 30 Jun 2010 11:29 Magnus Hagander <magnus(a)hagander.net> wrote: > Windows default for idle is 2 hours, for interval 1 second. And it defaults to five retries. With these settings, you could have a TCP connection break with as little as a five second network outage, if it happened to come after two hours of silence on the connection; although an outage of up to two hours could go totally unnoticed. The RFC values have a total of nine tries at 75 second intervals, so for a single network outage to break a connection, it would have to last at least ten minutes; but again, an outage of up to two hours could occur before it started to check for problems. I'm inclined toward option 2 (previously described on this thread), because the Windows defaults are dumb. Wait two hours and then test for five seconds??? I also think we may want to suggest that for most environments, people may want to change these settings to something more aggressive, like a 30 to 120 second initial delay, with a 10 or 20 second retry interval. The RFC defaults seem approximately right for a TCP connection to a colony on the surface of the moon, where besides the round trip latency of 2.5 seconds they might have to pay by the byte. In other words, it is *so* conservative that I have trouble seeing it ever causing a problem compared to not having keepalive enabled, but it will eventually clean things up. In practice people usually want something more aggressive. -Kevin -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
From: Tom Lane on 30 Jun 2010 10:48 Magnus Hagander <magnus(a)hagander.net> writes: > On Wed, Jun 30, 2010 at 16:27, Tom Lane <tgl(a)sss.pgh.pa.us> wrote: >> It's hard to argue about this when most of us have no idea what these >> "system defaults" are, or whether they really are any different from the >> RFC values in the first place, or whether ordinary users know how to >> alter them or even find out their values. �Please provide some >> background if you want intelligent comments. > The system defaults are whatever the user has configured at a machine > level (by editing the registry, by hand or by tool (including > policies)). I doubt many users have configured them by hand. There may > well be tools that do it for them. But you previously stated that this code was ignoring the registry values. So doesn't "system defaults" boil down to whatever Windows' wired-in defaults are? regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
From: Tom Lane on 30 Jun 2010 11:21
Bruce Momjian <bruce(a)momjian.us> writes: > Tom Lane wrote: >> What's your idea of "affecting the fewest people"? There is no previous >> history to be backward-compatible with, because we never supported >> keepalive on Windows before. > Well, starting in 9.0, keepalives in libpq will default to 'on': Yes, which is already a change in behavior. I don't understand why you are worrying about "backwards compatibility" to parameter values that weren't in use before. I think self-consistency of the new version is far more important than that. > even if we use Windows defaults, those defaults might be different for > different Windows versions. I'm not sure if that's an issue or not, but if it is, that seems to me to argue for #2 not #1. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers |