Re: Memory leak in for loops

[Mike Frysinger]

On Thursday 30 April 2009 05:56:02 Jan Schampera wrote:
> Sandino Araico Sánchez wrote:
> >    1.
> >       #!/bin/bash
> >    2.
> >
> >    3.
> >       for i in {0..150000000} ; do
> >    4.
> >               echo $i > /dev/null
> >    5.
> >       done
> >
> >
> >
> > Repeat-By:
> >         Run the script above and the process starts leaking memory very
> > fast.
>
> You know what a memory *leak* is, yes? mallocs() without proper free()s.
>
> What you mean is that your memory is used. Feel free to calculate the
> memory that is needed to store the string representation of
> {0..150000000}, I think you will get a number near your RAM size.

granted his example is wrong and his reasoning incorrect, there may actually 
be a leak here ...

bash-4.0$ ps -p $$ -F
UID        PID  PPID  C    SZ   RSS PSR STIME TTY          TIME CMD
vapier   27999 16493  0  5675  3052   1 18:51 pts/1    00:00:00 bash --norc
bash-4.0$ for n in {0..150000000} ; do echo $n; done
<wait a few seconds>^C
bash-4.0$ ps -p $$ -F
UID        PID  PPID  C    SZ   RSS PSR STIME TTY          TIME CMD
vapier   27999 16493 17 392694 473236 1 18:51 pts/1    00:00:01 bash --norc

that memory never goes away and bash will chew significant CPU (~10%) while it 
should be idle ...
-mike

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