On Thu, Jul 09, 2009 at 03:51:27PM +0200, Werner Fink wrote:
> Hi,
>
> I've just to report a memory leak caused by a shell function which
> uses an echo as last line in the shell function.
>
> -----------------------------------------------------------------------
> #!/usr/bin/ksh
>
> PATH=/bin:/usr/bin:/usr/sbin:/sbin
>
> # Description: Get the interval to sample information
> # Output: interval seconds
> getSampleInterval()
> {
> # Example for this arithmetic, suppose the next time is 45 second
> # If current second is in [35, 40], such as 38,
> # the interval should be 10 - 38 % 10 + 5 = 7
> # If current second is in [41, 45], such as 42,
> # the interval should be 10 - 42 % 10 - 5 = 3
> # If the current second is 45, the interval should be 10 - 45 % 10 - 5 = 0
>
> typeset -ilu _currSec=$(date +%S)
> typeset -ilu _interval
>
> ((_interval=10-(_currSec%10)))
>
> if ((_interval >= 5))
> then
> ((_interval=_interval-5))
> else
> ((_interval=_interval+5))
> fi
>
> echo $_interval
> }
>
> typeset -ilu times=0
> typeset -ilu interval
>
> while [ 1 -eq 1 ]
> do
> # First, get the interval to check
> interval=$(getSampleInterval)
> sleep $interval
>
> ((times++))
>
> state=$(egrep '^VmData|^VmRSS|^VmSize' </proc/$$/status)
> [ "$state" != "$oldstate" ] && echo $state
> oldstate="$state"
> done
> -----------------------------------------------------------------------
Found the following three problems:
in src/cmd/ksh93/sh/xec.c in function sh_funct() in the first line
nv_putval(SH_FUNNAMENOD, nv_name(np),NV_NOFREE);
the allocated Namfun_t of the builtin node SH_FUNNAMENOD is set
but never freed in src/cmd/ksh93/sh/subshell.c in function nv_restore().
The same for src/cmd/ksh93/bltins/misc.c in function b_dot_cmd()
in the first line
nv_putval(SH_PATHNAMENOD, shp->st.filename ,NV_NOFREE);
the allocated Namfun_t of the builtin node SH_PATHNAMENOD is set
but never freed in src/cmd/ksh93/sh/subshell.c in function nv_restore().
At last but not least in src/cmd/ksh93/sh/xec.c in function init_level()
the struct Level is allocated as Namfun_t of the builtin node
SH_LEVELNOD but also never freed in nv_restore().
In src/cmd/ksh93/sh/subshell.c in function nv_restore() the
allocated Namfun_t will be overwritten in the line
mp->nvfun = np->nvfun;
moreover it seems that at least for the nodes SH_FUNNAMENOD and
SH_PATHNAMENOD the cached values will be cloned by allocation
further memory for the already allocated Namfun_t for every
cycle of the loop.
How this can be avoided?
Werner
--
"Having a smoking section in a restaurant is like having
a peeing section in a swimming pool." -- Edward Burr
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