Re: [HACKERS] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
On Thu, Jun 24, 2010 at 11:50 PM, Tom Lane wrote: > Robert Haas writes: >> On Thu, Jun 24, 2010 at 1:38 PM, Simon Riggs wrote: >>> On Thu, 2010-06-24 at 11:15 -0400, Tom Lane wrote: It might be a good idea to add a sentence to the documentation, though, just pointing out that these control client-side keepalive probes rather than server-side. >>> >>> Yes please. I was confused; I think others will be also. > >> Do either of you have any thoughts about where would be the best place >> to add such a sentence? > > In the hunk you added to libpq.sgml would be fine by me. Well, the trick is that the hunk that I added is really four separate sections, and adding a whole sentence to each one seems like overkill. Here's an attempt at rewording the sections so that the information is included in each parameter's description without taking up a whole sentence. Thoughts? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise Postgres Company libpq-keepalive-docs.patch Description: Binary data -- 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
Robert Haas writes: > On Thu, Jun 24, 2010 at 1:38 PM, Simon Riggs wrote: >> On Thu, 2010-06-24 at 11:15 -0400, Tom Lane wrote: >>> It might be a good idea to add a sentence to the documentation, though, >>> just pointing out that these control client-side keepalive probes rather >>> than server-side. >> >> Yes please. I was confused; I think others will be also. > Do either of you have any thoughts about where would be the best place > to add such a sentence? In the hunk you added to libpq.sgml would be fine by me. regards, tom lane -- 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
On Thu, Jun 24, 2010 at 1:38 PM, Simon Riggs wrote: > On Thu, 2010-06-24 at 11:15 -0400, Tom Lane wrote: >> Florian Pflug writes: >> > On Jun 24, 2010, at 16:45 , Robert Haas wrote: >> >> I think the existing names are fine - people should understand that >> >> "options" means "server-side options" and that anything else is a >> >> client-side option. However, if there's a strong consensus the other >> >> way and someone feels like working up a patch, that's fine too. >> >> > I'd volunteer to create the patch if people think renaming the libpq >> > options is a good idea. >> >> I'm with Robert: the names are fine as-is. We've not had complaints >> about the libpq SSL parameters being confusingly like server-side SSL >> parameters, for instance. >> >> It might be a good idea to add a sentence to the documentation, though, >> just pointing out that these control client-side keepalive probes rather >> than server-side. > > Yes please. I was confused; I think others will be also. Do either of you have any thoughts about where would be the best place to add such a sentence? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise Postgres Company -- 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
On Thu, Jun 24, 2010 at 1:40 PM, Simon Riggs wrote: > On Thu, 2010-06-24 at 10:30 -0400, Robert Haas wrote: > >> It lets you set >> the TCP keepalive parameters on the server side, whereas what this >> patch does is let you set them on the client side. Only setting them >> on the client side will allow the client to notice when the server has >> gone away. > > Thank you for explaining. Now I understand. > > It sort of begs the question: why need they be different? In most cases, they probably don't; in fact, I suspect most people don't bother adjusting these parameters at all. Essentially, they just control the amount of time that can pass before you decide that the other guy is dead. And if the client thinks it's right to declare the server dead after X minutes, it's probably reasonable for the server to declare the client dead after X minutes, too. On the other hand, the client and server may be under different administrative control. What the DBA wants the database to do to avoid running out of connection slots might not be the same as what the application writer wants to do to detect when the database has crashed. For that exact reason, it's actually slightly strange that we make these parameters PGC_USERSET on the server side - but not strange enough that I can get excited about changing it. If an application writer wants to make trouble for the DBA, he certainly has better ways to do it than this... -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise Postgres Company -- 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
On Thu, 2010-06-24 at 10:30 -0400, Robert Haas wrote: > It lets you set > the TCP keepalive parameters on the server side, whereas what this > patch does is let you set them on the client side. Only setting them > on the client side will allow the client to notice when the server has > gone away. Thank you for explaining. Now I understand. It sort of begs the question: why need they be different? -- Simon Riggs www.2ndQuadrant.com -- 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
On Thu, 2010-06-24 at 11:15 -0400, Tom Lane wrote: > Florian Pflug writes: > > On Jun 24, 2010, at 16:45 , Robert Haas wrote: > >> I think the existing names are fine - people should understand that > >> "options" means "server-side options" and that anything else is a > >> client-side option. However, if there's a strong consensus the other > >> way and someone feels like working up a patch, that's fine too. > > > I'd volunteer to create the patch if people think renaming the libpq > > options is a good idea. > > I'm with Robert: the names are fine as-is. We've not had complaints > about the libpq SSL parameters being confusingly like server-side SSL > parameters, for instance. > > It might be a good idea to add a sentence to the documentation, though, > just pointing out that these control client-side keepalive probes rather > than server-side. Yes please. I was confused; I think others will be also. -- Simon Riggs www.2ndQuadrant.com -- 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
Florian Pflug writes: > On Jun 24, 2010, at 16:45 , Robert Haas wrote: >> I think the existing names are fine - people should understand that >> "options" means "server-side options" and that anything else is a >> client-side option. However, if there's a strong consensus the other >> way and someone feels like working up a patch, that's fine too. > I'd volunteer to create the patch if people think renaming the libpq options > is a good idea. I'm with Robert: the names are fine as-is. We've not had complaints about the libpq SSL parameters being confusingly like server-side SSL parameters, for instance. It might be a good idea to add a sentence to the documentation, though, just pointing out that these control client-side keepalive probes rather than server-side. regards, tom lane -- 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
On Jun 24, 2010, at 16:45 , Robert Haas wrote: > On Thu, Jun 24, 2010 at 10:40 AM, Florian Pflug wrote: >> On Jun 24, 2010, at 16:30 , Robert Haas wrote: >>> On Thu, Jun 24, 2010 at 10:13 AM, Tom Lane wrote: Simon Riggs writes: > There isn't any need at at all for this. We can already add options on > the libpq connection line. > options = '-o tcp_keepalives_idle=X > tcp_keepalives_interval=Y > tcp_keepalives_count=Z' Huh? The above is 100% fanciful; there was no code in libpq or anywhere else that would have processed such a thing. >>> >>> You can do this: >>> >>> psql "host=127.0.0.1 options='-c tcp_keepalives_idle=1'" >> >> Hm, seems a bit error-prone though. The difference between the above >> >> psql "host=127.0.0.1 keepalives=1" >> >> isn't immediately obvious I'd say. >> >> Should we maybe rename the libpq-side parameters to tcp_client_keepalives, >> tcp_client_keepalives_idle, tcp_client_keepalives_count and >> tcp_client_keepalives_interval? Or do we expect people who fiddle with those >> parameters to understand the subtle difference? > > I think the existing names are fine - people should understand that > "options" means "server-side options" and that anything else is a > client-side option. However, if there's a strong consensus the other > way and someone feels like working up a patch, that's fine too. I'd volunteer to create the patch if people think renaming the libpq options is a good idea. 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
On Thu, Jun 24, 2010 at 10:40 AM, Florian Pflug wrote: > On Jun 24, 2010, at 16:30 , Robert Haas wrote: >> On Thu, Jun 24, 2010 at 10:13 AM, Tom Lane wrote: >>> Simon Riggs writes: There isn't any need at at all for this. We can already add options on the libpq connection line. >>> options = '-o tcp_keepalives_idle=X tcp_keepalives_interval=Y tcp_keepalives_count=Z' >>> >>> Huh? The above is 100% fanciful; there was no code in libpq or anywhere >>> else that would have processed such a thing. >> >> You can do this: >> >> psql "host=127.0.0.1 options='-c tcp_keepalives_idle=1'" > > Hm, seems a bit error-prone though. The difference between the above > > psql "host=127.0.0.1 keepalives=1" > > isn't immediately obvious I'd say. > > Should we maybe rename the libpq-side parameters to tcp_client_keepalives, > tcp_client_keepalives_idle, tcp_client_keepalives_count and > tcp_client_keepalives_interval? Or do we expect people who fiddle with those > parameters to understand the subtle difference? I think the existing names are fine - people should understand that "options" means "server-side options" and that anything else is a client-side option. However, if there's a strong consensus the other way and someone feels like working up a patch, that's fine too. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise Postgres Company -- 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
On Jun 24, 2010, at 16:30 , Robert Haas wrote: > On Thu, Jun 24, 2010 at 10:13 AM, Tom Lane wrote: >> Simon Riggs writes: >>> On Wed, 2010-06-23 at 21:54 +, Robert Haas wrote: This adds four additional connection parameters to libpq: keepalives, keepalives_idle, keepalives_count, and keepalives_interval. keepalives default to on, per discussion, but can be turned off by specifying keepalives=0. The remaining parameters, where supported, can be used to adjust how often keepalives are sent and how many can be lost before the connection is broken. >> >>> There isn't any need at at all for this. We can already add options on >>> the libpq connection line. >> >>> options = '-o tcp_keepalives_idle=X >>> tcp_keepalives_interval=Y >>> tcp_keepalives_count=Z' >> >> Huh? The above is 100% fanciful; there was no code in libpq or anywhere >> else that would have processed such a thing. > > You can do this: > > psql "host=127.0.0.1 options='-c tcp_keepalives_idle=1'" Hm, seems a bit error-prone though. The difference between the above psql "host=127.0.0.1 keepalives=1" isn't immediately obvious I'd say. Should we maybe rename the libpq-side parameters to tcp_client_keepalives, tcp_client_keepalives_idle, tcp_client_keepalives_count and tcp_client_keepalives_interval? Or do we expect people who fiddle with those parameters to understand the subtle difference? 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
On Thu, Jun 24, 2010 at 10:13 AM, Tom Lane wrote: > Simon Riggs writes: >> On Wed, 2010-06-23 at 21:54 +, Robert Haas wrote: >>> This adds four additional connection parameters to libpq: keepalives, >>> keepalives_idle, keepalives_count, and keepalives_interval. >>> keepalives default to on, per discussion, but can be turned off by >>> specifying keepalives=0. The remaining parameters, where supported, >>> can be used to adjust how often keepalives are sent and how many >>> can be lost before the connection is broken. > >> There isn't any need at at all for this. We can already add options on >> the libpq connection line. > >> options = '-o tcp_keepalives_idle=X >> tcp_keepalives_interval=Y >> tcp_keepalives_count=Z' > > Huh? The above is 100% fanciful; there was no code in libpq or anywhere > else that would have processed such a thing. You can do this: psql "host=127.0.0.1 options='-c tcp_keepalives_idle=1'" ...but it doesn't do the same thing as this patch. It lets you set the TCP keepalive parameters on the server side, whereas what this patch does is let you set them on the client side. Only setting them on the client side will allow the client to notice when the server has gone away. There is still an open question in my mind as to whether this is really an adequate solution to the walrecevier problem, but as you say, if it turns out not to be, it's got other value. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise Postgres Company -- 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
Simon Riggs writes: > On Wed, 2010-06-23 at 21:54 +, Robert Haas wrote: >> This adds four additional connection parameters to libpq: keepalives, >> keepalives_idle, keepalives_count, and keepalives_interval. >> keepalives default to on, per discussion, but can be turned off by >> specifying keepalives=0. The remaining parameters, where supported, >> can be used to adjust how often keepalives are sent and how many >> can be lost before the connection is broken. > There isn't any need at at all for this. We can already add options on > the libpq connection line. > options = '-o tcp_keepalives_idle=X > tcp_keepalives_interval=Y > tcp_keepalives_count=Z' Huh? The above is 100% fanciful; there was no code in libpq or anywhere else that would have processed such a thing. The bigger picture is that this patch is needed, not only for walreceiver but for many other purposes --- the feature has been requested repeatedly over the years and was already in the 9.1 commitfest queue. We moved it up because it seemed fairly important for walreceiver's purposes, but it would have gotten done in the very near future anyway. regards, tom lane -- 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] [COMMITTERS] pgsql: Add TCP keepalive support to libpq.
On Wed, 2010-06-23 at 21:54 +, Robert Haas wrote: > Log Message: > --- > Add TCP keepalive support to libpq. I misunderstood the earlier discussion on this and didn't realise you were considering committing in this way. For me, this is two patches, not one. I object to one and like the other. > This adds four additional connection parameters to libpq: keepalives, > keepalives_idle, keepalives_count, and keepalives_interval. > keepalives default to on, per discussion, but can be turned off by > specifying keepalives=0. The remaining parameters, where supported, > can be used to adjust how often keepalives are sent and how many > can be lost before the connection is broken. There isn't any need at at all for this. We can already add options on the libpq connection line. options = '-o tcp_keepalives_idle=X tcp_keepalives_interval=Y tcp_keepalives_count=Z' I see zero need to further complicate the libpq interface. If it changes frequently between releases then supporting PostgreSQL programs becomes much harder and leads to software not working correctly with Postgres. Connecting to Postgres is already too complex. At most it needs an example in the manual to show how to do this the existing way. I'm sorry to express this opinion now, again because I misunderstood. > The immediate motivation for this patch is to make sure that > walreceiver will eventually notice if the master reboots without > closing the connection cleanly, but it should be helpful in other > cases as well. My understanding is that the motivation for this is that the above options parameter would not have worked? So I regard making that work as a bug fix, so agree with some parts of this patch, I think. -- Simon Riggs www.2ndQuadrant.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
