Обсуждение: pg_recvlogical, stdout and SIGHUP
pg_recvlogical re-opens the output file on SIGHUP. If the output goes to stdout, it will close stdout on SIGHUP. That's a bug, isn't it? Another thing I noticed is that if when the output goes to a file, the file isn't re-opened immediately on SIGHUP. Only after receiving some data from the server. I believe that's also not intentional. - Heikki
On 2014-05-13 16:31:25 +0300, Heikki Linnakangas wrote: > pg_recvlogical re-opens the output file on SIGHUP. If the output goes to > stdout, it will close stdout on SIGHUP. That's a bug, isn't it? Yes. An annoying one at that because it'll mean a a new connection will use that fd and we'll start writing stdout stuff to it... > Another thing I noticed is that if when the output goes to a file, the file > isn't re-opened immediately on SIGHUP. Only after receiving some data from > the server. I believe that's also not intentional. Hm. I can't really get excited about that one. Not doing that seems to complicate matters unneccessarily. What's the problem here? Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services
On 05/13/2014 04:35 PM, Andres Freund wrote: > On 2014-05-13 16:31:25 +0300, Heikki Linnakangas wrote: >> Another thing I noticed is that if when the output goes to a file, the file >> isn't re-opened immediately on SIGHUP. Only after receiving some data from >> the server. I believe that's also not intentional. > > Hm. I can't really get excited about that one. Not doing that seems to > complicate matters unneccessarily. What's the problem here? Not sure if it matters in any real-world scenario, but I found it pretty surprising while playing with it. It should be trivial to fix; ISTM the problem is that there is a "continue" in the loop when select() is interrupted by signal, but the re-opening is done after the select() in the loop. I think all you need to do is move the check for output_reopen to the beginning of the loop. - Heikki
On 2014-05-13 17:43:47 +0300, Heikki Linnakangas wrote: > On 05/13/2014 04:35 PM, Andres Freund wrote: > >On 2014-05-13 16:31:25 +0300, Heikki Linnakangas wrote: > >>Another thing I noticed is that if when the output goes to a file, the file > >>isn't re-opened immediately on SIGHUP. Only after receiving some data from > >>the server. I believe that's also not intentional. > > > >Hm. I can't really get excited about that one. Not doing that seems to > >complicate matters unneccessarily. What's the problem here? > > Not sure if it matters in any real-world scenario, but I found it pretty > surprising while playing with it. It should be trivial to fix; ISTM the > problem is that there is a "continue" in the loop when select() is > interrupted by signal, but the re-opening is done after the select() in the > loop. I think all you need to do is move the check for output_reopen to the > beginning of the loop. Thanks for fixing and sorry for being slow :(. Any reason you didn't also move the opening of the output file up? It seems a bit odd to not have an output file existing every now and then... Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services
On 05/15/2014 07:59 PM, Andres Freund wrote: > On 2014-05-13 17:43:47 +0300, Heikki Linnakangas wrote: >> On 05/13/2014 04:35 PM, Andres Freund wrote: >>> On 2014-05-13 16:31:25 +0300, Heikki Linnakangas wrote: >>>> Another thing I noticed is that if when the output goes to a file, the file >>>> isn't re-opened immediately on SIGHUP. Only after receiving some data from >>>> the server. I believe that's also not intentional. >>> >>> Hm. I can't really get excited about that one. Not doing that seems to >>> complicate matters unneccessarily. What's the problem here? >> >> Not sure if it matters in any real-world scenario, but I found it pretty >> surprising while playing with it. It should be trivial to fix; ISTM the >> problem is that there is a "continue" in the loop when select() is >> interrupted by signal, but the re-opening is done after the select() in the >> loop. I think all you need to do is move the check for output_reopen to the >> beginning of the loop. > > Thanks for fixing and sorry for being slow :(. > > Any reason you didn't also move the opening of the output file up? It > seems a bit odd to not have an output file existing every now and > then... No particular reason. But that would actually be a great idea, because currently you won't get any error you give pg_recvlogical an invalid path, until it receives the first piece of data from the server and tries to write it to the file. I'll go and do that. - Heikki