Informix spawning threads every 5 seconds
We have Informix 7.23 UC3 running under AIX 4.2.1. Aio has been activated. Using vmstat, I have observed that the number of runnable kernel threads jumps from 0-1 to 19-21 every 5 seconds. This does not occur when Informix has been stopped, so I am guessing that Informix is causing this. Any thought as to what is going on, and what I can (should?) do about it would be appreciated. Thanks. -- Sam Johnson Sam.Johnson@FernUni-Hagen.de ------------------------------------------------------------------------------ FernUniversitaet Phone: +49-2331-987-2874,-2799 58084 Hagen, Germany Fax: +49-2331-987-2720
In article <8id17o$8o$1@oak.fernuni-hagen.de>, Johnson <johnson@kudzu.fernuni-hagen.de> writes >We have Informix 7.23 UC3 running under AIX 4.2.1. Aio has been activated. >Using vmstat, I have observed that the number of runnable kernel threads jumps >from 0-1 to 19-21 every 5 seconds. This does not occur when Informix has >been stopped, so I am guessing that Informix is causing this. >Any thought as to what is going on, and what I can (should?) do about it would >be appreciated. > >Thanks. Possibly a user building several small indexes or altering several small tables. Informix can allocate several threads to index builds and small index builds can finish quickly. Informix uses a hybrid of user-space based and kernel based threading. Possibly the new kernel threads are when user sessions cause new user space threads to need another kernel thread. This is very much deep into the internals of online and a) not documented b) platform specific c) Informix version specific. Can you get stack traces from the kernel threads?? -- David Williams
David Williams <djw@smooth1.demon.co.uk> wrote: : In article <8id17o$8o$1@oak.fernuni-hagen.de>, Johnson : <johnson@kudzu.fernuni-hagen.de> writes :>We have Informix 7.23 UC3 running under AIX 4.2.1. Aio has been activated. :>Using vmstat,I have observed that the number of runnable kernel threads jumps :>from 0-1 to 19-21 every 5 seconds. ... : Possibly a user building several small indexes or altering several : small tables. Informix can allocate several threads to index builds : and small index builds can finish quickly. : Informix uses a hybrid of user-space based and kernel based threading. : Possibly the new kernel threads are when user sessions cause new user : space threads to need another kernel thread. This is very much deep : into the internals of online and : : a) not documented : b) platform specific : c) Informix version specific. : Can you get stack traces from the kernel threads?? I don't believe that it can be correlated with user activity, which would show a more random pattern. What I am seeing is a sudden jump every 5 second, as if some internal processes from informix were schduled to run every five seconds. I read something about cleaners, but they run every sixty seconds. I guess. -- Sam Johnson Sam.Johnson@FernUni-Hagen.de ------------------------------------------------------------------------------ FernUniversitaet Phone: +49-2331-987-2874,-2799 58084 Hagen, Germany Fax: +49-2331-987-2720
In article <8il6p7$caf$1@oak.fernuni-hagen.de>, johnson@kudzu.fernuni- hagen.de says... > David Williams <djw@smooth1.demon.co.uk> wrote: > : In article <8id17o$8o$1@oak.fernuni-hagen.de>, Johnson > : <johnson@kudzu.fernuni-hagen.de> writes > :>We have Informix 7.23 UC3 running under AIX 4.2.1. Aio has been activated. > :>Using vmstat,I have observed that the number of runnable kernel threads jumps > :>from 0-1 to 19-21 every 5 seconds. > ... > : Possibly a user building several small indexes or altering several > : small tables. Informix can allocate several threads to index builds > : and small index builds can finish quickly. > > : Informix uses a hybrid of user-space based and kernel based threading. > : Possibly the new kernel threads are when user sessions cause new user > : space threads to need another kernel thread. This is very much deep > : into the internals of online and > : > : a) not documented > : b) platform specific > : c) Informix version specific. > > : Can you get stack traces from the kernel threads?? > > > I don't believe that it can be correlated with user activity, which > would show a more random pattern. What I am seeing is a sudden jump > every 5 second, as if some internal processes from informix were > schduled to run every five seconds. I read something about cleaners, > but they run every sixty seconds. I guess. > Check to see if you have IECC or its agent running. It spawns a new thread about every five seconds. I spoke with tech support about a year ago on this issue, hoping they could open a pipe rather than individual network connections and they said it might make a future release.