问题
I am running Ubuntu Linux (2.6.28-11-generic #42-Ubuntu SMP Fri Apr 17 01:57:59 UTC 2009 i686 GNU/Linux) and it seems that the command "ulimit -t" does not work properly. I ran:
ulimit -t 1; myprogram
where 'myprogram' is an endless loop. I expected the program to be interrupted after 1 second, but it did not stop. I tried the same thing on a Linux Fedora installation and it worked as expected.
Is there some configuration that has to be set for it to work properly?
-- tsf
回答1:
As Tsf pointed out, the problem is due to a bug in kernel 2.6.28. I leave my original answer, because I think it could be helpful anyway.
From the ulimit manpage
-t The maximum amount of cpu timein seconds.
What counts in respect to ulimit is only CPU time. Try to start your program like this:
time myprogram
That will show you how much CPU time it really uses.
My suspicion is that your endless loop contains sleep()
and sleep time does not contribute to the CPU time of the process.
This gets killed after one second:
me@host:~$ bash
me@host:~$ ulimit -t 1; for (( i=1; 1; i++ )); do a=1; done
Killed
This seems to run forever (but of course does not):
me@host:~$ bash
me@host:~$ ulimit -t 1; for (( i=1; 1; i++ )); do sleep 1; done
Measure CPU time like this...
me@host:~$ time for (( i=1; i<5; i++ )); do sleep 1; done
...and 5 seconds later...
real 0m4.008s
user 0m0.000s
sys 0m0.012s
...only 12 ms CPU time used.
I tried it on ubuntu Jaunty Jackalope (9.04)
Linux host 2.6.28-11-generic #42-Ubuntu SMP
Fri Apr 17 01:57:59 UTC 2009 i686 GNU/Linux
来源：https://stackoverflow.com/questions/978317/ulimit-t-under-ubuntu