Re: tight loop on select/ioctl on X socket under certain conditions

Thanks Rick. I've confimed that I have the latest tusc version as
found at
http://hpux.connect.org.uk/hppd/cgi-bin/search?package=&term=/tusc
$ tusc -V
tusc: version 7.8, 2005/08/09, Copyright (c) 1996-2005 Chris Bertin
(HP).

and it looks like the timeout setting is very low already so something
about my different parameters is causing it to have an immediately
expired timer every time it comes back to search for more data.

I believe the timeout is set a 2 seconds and all subsequent calls
cascading in my second scenario. Does this mean I should be going down
to the base libraries that call this to change the timeout?
XtAppMainLoop I thought - I don't know how to do that...

From 1st scenario where CPU not in a busy loop:
timeout.tv_sec: 0
timeout.tv_usec: 0
timeout.tv_sec: 0
timeout.tv_usec: 0
timeout.tv_sec: 0
timeout.tv_usec: 902386
timeout.tv_sec: 0
timeout.tv_usec: 0
timeout.tv_sec: 0
timeout.tv_usec: 0
timeout.tv_sec: 0
timeout.tv_usec: 741601
timeout.tv_sec: 0
timeout.tv_usec: 0
timeout.tv_sec: 0
timeout.tv_usec: 470834
timeout.tv_sec: 2
timeout.tv_usec: 0

From problematic scenario:
timeout.tv_sec: 0
timeout.tv_usec: 0
timeout.tv_sec: 0
timeout.tv_usec: 0
timeout.tv_sec: 0

Rick Jones wrote:
John.K.D.Ko@xxxxxxxxx wrote:
I'm using tusc/truss to trace system calls of my program on HPUX11.11
and it appears that it gets caught in a select loop trying to read from
a file descriptor. I've got 2 scenarios where in the first instance,
there seems to be a pause/sleeping on the select call (and a reasonable
number of events) and another where it just goes crazy. Can someone
please tell me if I'm interpreting the output correctly and offer
suggestions as to how to proceed?

I'm getting these by the tens of thousands.
select(17, 0x7f7f0c54, 0x7f7f0d54, 0x7f7f0e54, 0x7f7f0c48) = 0
gettimeofday(0x7f7f0b80, NULL) ........................... = 0
ioctl(4, FIONREAD, 0x7f7f0bc0) ........................... = 0
ioctl(4, FIONREAD, 0x7f7f0bc0) ........................... = 0
select(17, 0x7f7f0c54, 0x7f7f0d54, 0x7f7f0e54, 0x7f7f0c48) = 0
gettimeofday(0x7f7f0b80, NULL) ........................... = 0
ioctl(4, FIONREAD, 0x7f7f0bc0) ........................... = 0

It would be good to see the arguments being passed to select() - in
particular the timeout settings. So, add a -v to the tusc options to
get verbose output.

BTW, make sure you have the latest tusc - either from (IIRC)
devresource.hp.com or from ftp.cup.hp.com/dist/networking/tools/

rick jones
--
oxymoron n, commuter in a gas-guzzling luxury SUV with an American flag
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

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