Re: [bug-gawk] [BugReport] GAWK 3.1.8 / gsub() memory leak

[Aharon Robbins]

Greetings. Re: this:

> From: "Koehler, Mario" <address@hidden>
> To: "'address@hidden'" <address@hidden>
> Date: Thu, 29 Nov 2012 09:29:29 +0100
> Subject: [bug-gawk] [BugReport] GAWK 3.1.8 / gsub() memory leak
>
> Hi,
>
> i would like to report a memory leak in gensub() and gsub() functions of
> GAWK 3.1.8. The bug seems to be introduced somewhere between 3.1.5 and
> 3.1.8. Those two versions are the ones I have access to, and in 3.1.5
> the bug does not occur, but in 3.1.8 it does.
>
> The memory leak scenario can be reproduced with this small AWK script:
>
> {
>     outputLineTemplate = "COMP_ID-KKTNR-KUKTO|CAP_NAME|CAP_STR 
> KBHNR|PADDED_PLZ|CAP_ORT|BIRTHDAY|256,COMP_NR|TELEPHONE";
>     tokenList = "COMP_NR COMP_ID KKTNR KUKTO CAP_NAME BIRTHDAY CAP_STR KBHNR 
> PADDED_PLZ CAP_ORT TELEPHONE"
>     tokenCount = split(tokenList, definedTokens, " ");
>
>     while (1 > 0) {
>          outline = outputLineTemplate;
>          for( token = 1; token <= tokenCount; token++ ) {
>            gsub(definedTokens[token],"example value",outline);
>          }
>          print outline;
>     }
> }
>
> The script defines a "template" for an output line that contains
> placeholders. Then it iterates over this output line template and replaces
> each placeholder (token) in the template with a certain value ("example
> value" in this case). This is repeated in an infinite loop to simulate the
> processing of a large batch of input lines. The script was originally part
> of a much larger "conversion script" and this relevant part was extracted
> from there and slightly modified for the purpose of this bug report.
> 
> The most important line is the line with the gsub() call (replacing it
> with gensub() also produces the bug). This call causes a memory leak to
> occur, which can be easily observed by starting the script and then watch
> "top" for a while. You will see that the memory usage of the awk process
> will rise continually.
> 
> If you repeat this test with GAWK 3.1.5 you will see that the memory usage
> of the awk process will remain constant at a very low level (couple of KB)
>
> I did my testing on SUSE Linux Enterprise Server 11.2 (x86_64).
>
> Best regards
> Mario K?hler

Thank you for taking the time to send in a bug report. I appreciate
your concern.

I can indeed reproduce this.

Fortunately, the bug has been fixed in subsequent versions. The current
released version is 4.0.1 and it does not display the bug.  It's not
obvious to me (now) what fixed the bug, but the 'gawk-stable' branch in
git, which has the few additional changes over 3.1.8, does not have the
bug either.

I suggest you simply download and install the current version. Cut & Paste:

        wget http://ftp.gnu.org/gnu/gawk/gawk-4.0.1.tar.gz
        tar -xpzf gawk-4.0.1.tar.gz
        cd gawk-4.0.1
        ./configure && make && make check
        sudo make install

:-)

Thanks,

Arnold

P.S. If you can get Suse to upgrade, all the better.