Configuration Information [Automatically generated, do not change]:
Machine: i486
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='i486'
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i486-pc-linux-gnu'
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL
-DHAVE_CONFIG_H -I. -I../bash -I../bash/include -I../bash/lib -g -O2 -Wall
uname output: Linux deskpro102485 2.6.32-41-generic-pae #94-Ubuntu SMP Fri Jul
6 17:08:20 UTC 2012 i686 GNU/Linux
Machine Type: i486-pc-linux-gnu
Bash Version: 4.1
Patch Level: 5
Release Status: release
Description:
If I have a process running in the background that finishes
while I have a foreground process being timed using the
builtin time command, then the CPU time of the background task
is erroneously added on to the foreground task. This does not
happen if the background task ends after the foreground task.
Repeat-By:
$ cat ~/tmp/loop.c
int main(int argc, char **argv) {
int i, j, x = 0;
int N = atoi(argv[1]);
int M = 1000000;
for (i = 0; i < N; i++)
for (j = 0; j < M; j++)
x += i*j;
return 0;
}
$ gcc -g ~/tmp/loop.c
$ ./a.out 1000 & time ./a.out 1100
[3] 14577
[3] Done ./a.out 1000
real 0m2.512s
user 0m4.772s
sys 0m0.008s
$ ./a.out 1200 & time ./a.out 1100
[3] 14579
real 0m2.528s
user 0m2.520s
sys 0m0.000s
$
Using a subshell avoids the problem:
$ ./a.out 1000 & (time ./a.out 1100)
[3] 14589
real 0m2.548s
user 0m2.536s
sys 0m0.000s
[3] Done ./a.out 1000
$ (./a.out 1000 &); time ./a.out 1100
real 0m2.502s
user 0m2.492s
sys 0m0.004s
Is this an issue with process groups?
--
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