[rrd-developers] Re: rrdtool segfault

[Tobias Oetiker]

Hi Matt,

gnu getopt is not useable for multithreaded applications due to its
use of globabl variables ...

not setting anything will help you here ... the only way out is to
replace gnu getopt with something less hacky ...

Peter Stamfest has written a patch for the developers version of
rrdtool which makes it threadsave. Check out:

http://www.ee.ethz.ch/~slist/rrd-developers/msg00988.html

this patch is in the devel codebase

tobi


Today Matt Scifo wrote:

> Hello
>
> I have a multi-threaded application, where each thread calls
> rrd_update().  At any given time, there are at least 125 threads running
> in parallel.  Each thread is responsible for calling rrd_update() using
> the following code...
>
> update(string filename, string datasources, string values)
> {
>     char *argv[6];
>
>     // add -t argument to datasources
>     datasources = "-t" + datasources;
>
>     // RRD library call
>     argv[0] = "update";
>     argv[1] = (char *)filename.c_str();
>     argv[2] = (char *)datasources.c_str();
>     argv[3] = (char *)values.c_str();
>     // Ex. argv = "update file.rrd -tDS1 N:U"
>
>     optind = 0;
>     opterr = 0;
>     if (rrd_update(4, argv) == -1)
>         results.push_back(rrd_get_error());
>     else
>         results.push_back("success");
>     rrd_clear_error();
> }
>
> At random times, the application segfaults, always returning the same
> backtrace.  Here is the gdb backtrace...
>
> #0  0x40101609 in confstr () from /lib/libc.so.6
> #1  0x4010237c in getopt_long () from /lib/libc.so.6
> #2  0x4002d2c4 in rrd_update () from /usr/lib/librrd.so.0
>
> I have read previous threads regarding the same problem, and they
> all indicate that it is necessary to clear the global vars optind
> and opterr before each call.  As you can see above, I have done this,
> yet I am still receiving segfaults.
>
> I am running on RH8.0 with RRD 1.0.45.
>
> Can anyone provide any help?
>
> Thanks
>
> -Matt Scifo
>
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