[OSM-dev] renderd segfaulting

Artem Pavlenko artem.mapnik at googlemail.com
Tue Aug 5 23:56:43 BST 2008

On 5 Aug 2008, at 20:26, Jon Burgess wrote:

> On Tue, 2008-08-05 at 12:04 -0700, Mikel Maron wrote:
>>>> I've set up mod_tile and renderd. Compiled against mapnik 0.5.1.
>>>> renderd works for a bit, but then segfaults. It seems to be a
>> problem with fielding a burst concurrent requrests, but not certain.
>>>> Any suggestions on problems to look for?
>>> What compile options did you use for compiling Mapnik? If you set
>>> THREADING=single then that could be the problem. It might be worth
>>> switching renderd to be single threaded by editing render_config.h
>> to
>>> NUM_THREADS to 1 and recompile.
>> I didn't compile Mapnik with any THREADING option .. assume it
>> defaults to multi?
>> Changing NUM_THREADS to 1 and recompiling does prevent segfaults.
>> Doesn't explain the problem though, and I'd like to get multiple
>> threads working, if possible.
>>> The code operates fine in multi-threaded mode on the main OSM server
>>> which uses the latest SVN mapnik code.
>>> If you still run into problems then it would be good to recompile
>>> renderd with debug info by adding -g to the CFLAGS/CXXFLAGS and get
>> a
>>> backtrace from gdb.
>> Running renderd in gdb, it segfaults in "fribidi_remove_bidi_marks"
> Ah, multithreading with fribidi would be the problem. From what I
> recall, the solution that Artem found was to switch to using libicu
> instead :-). This change was made some time ago in SVN but has not
> appeared in any release version. I'd recommend moving to the latest  
> code.

Jon is right, fribidi is not thread safe.  Using SVN trunk ( libicu )  
will solve this problem.
> 	Jon
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