Thread: SIGHUP during recovery
Hi, Currently, the startup process ignores SIGHUP. The attached patch allows the startup process to re-read config file: when SIGHUP arrives, the startup process also receives the signal from postmaster and reload the settings in main redo apply loop. Obviously, this is useful to change the parameters which the startup process may use (e.g. log_line_prefix, log_checkpoints). Any comments welcome. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
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Fujii Masao wrote: > Currently, the startup process ignores SIGHUP. > > The attached patch allows the startup process to re-read config file: > when SIGHUP arrives, the startup process also receives the signal > from postmaster and reload the settings in main redo apply loop. > Obviously, this is useful to change the parameters which the startup > process may use (e.g. log_line_prefix, log_checkpoints). Thanks, committed. The fact that bgwriter can run simultaneously with the startup process makes this more important than before. Otherwise if you change something like log_line_prefix, bgwriter will use the new setting but startup process will not. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com
On Wed, 2009-03-04 at 15:58 +0200, Heikki Linnakangas wrote: > Fujii Masao wrote: > > Currently, the startup process ignores SIGHUP. > > > > The attached patch allows the startup process to re-read config file: > > when SIGHUP arrives, the startup process also receives the signal > > from postmaster and reload the settings in main redo apply loop. > > Obviously, this is useful to change the parameters which the startup > > process may use (e.g. log_line_prefix, log_checkpoints). > > Thanks, committed. > > The fact that bgwriter can run simultaneously with the startup process > makes this more important than before. Otherwise if you change something > like log_line_prefix, bgwriter will use the new setting but startup > process will not. Should we reload recovery.conf also? -- Simon Riggs www.2ndQuadrant.comPostgreSQL Training, Services and Support
Hi, On Thu, Mar 5, 2009 at 6:28 PM, Simon Riggs <simon@2ndquadrant.com> wrote: > Should we reload recovery.conf also? I think no for now. At least the parameters which specify the recovery target should not be changed during recovery. On the other hand, restore_command maybe can be set safely, but I'm not sure if it's really useful at this time. Or, upcoming HS needs such capability? BTW, I found that backup.sgml still had the description of log_restartpoints. Here is the patch to remove it. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
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On Thu, 2009-03-05 at 19:52 +0900, Fujii Masao wrote: > Hi, > > On Thu, Mar 5, 2009 at 6:28 PM, Simon Riggs <simon@2ndquadrant.com> wrote: > > Should we reload recovery.conf also? > > I think no for now. At least the parameters which specify the recovery target > should not be changed during recovery. Why not? > On the other hand, restore_command > maybe can be set safely, but I'm not sure if it's really useful at this time. Not sure changing those parameters would be a bad thing. Other parameters can be changed, why not those? -- Simon Riggs www.2ndQuadrant.comPostgreSQL Training, Services and Support
Simon Riggs wrote: > On Thu, 2009-03-05 at 19:52 +0900, Fujii Masao wrote: >> Hi, >> >> On Thu, Mar 5, 2009 at 6:28 PM, Simon Riggs <simon@2ndquadrant.com> wrote: >>> Should we reload recovery.conf also? >> I think no for now. At least the parameters which specify the recovery target >> should not be changed during recovery. > > Why not? I don't see either why it wouldn't work. As long as the new value is greater than the current point in recovery. BTW, we now have some extra safeguards (minRecoveryPoint) in place to prevent you from corrupting your database by moving recovery target backwards to a point earlier than an already recovery xlog record. That's not really that relevant to reloading recovery.conf on the fly, but it's worth noting. The documentation currently says about the settings in recovery.conf that "They cannot be changed once recovery has begun." That wording should probably be relaxed. >> On the other hand, restore_command >> maybe can be set safely, but I'm not sure if it's really useful at this time. > > Not sure changing those parameters would be a bad thing. Other > parameters can be changed, why not those? It seems safe to me. It doesn't seem very useful, though. The only options left in recovery.conf are restore_command, and all the target-related options. If you want to change those, you can always stop the server, change the settings and restart; without hot standby there isn't any other backends active yet that would get upset about the shutdown. The main reason why reloading the main config file on SIGHUP is a good idea is that otherwise you get an inconsistency between the background writer and the startup process. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com
Fujii Masao wrote: > BTW, I found that backup.sgml still had the description of log_restartpoints. > Here is the patch to remove it. Thanks, I had put that in the Open Items list so that we remember to do that before release. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com
Fujii Masao <masao.fujii@gmail.com> writes:
> BTW, I found that backup.sgml still had the description of log_restartpoints.
> Here is the patch to remove it.
Applied, thanks.
regards, tom lane