Comment 3 for bug 984836

> but when executing the filter code appears to go into an infinite loop

Every time? I manage to produce such hangs (not consistently though) when e.g. quickly clicking on the canvas to select something while screen redrawing is still in process with a complex filter example, but basic rendering for example of the 'share/examples/filters.svg' file is ok, at whatever zoom level I choose.

Overall - in my tests on two different systems - rendering performance is noticeably better with OpenMP support enable (despte occasional hangs):

Tests with optimized (-O2) builds run on
- Mac OS X 10.5.8 i386 (Apple GCC 4.2.1)
- OS X 10.7.2 (Apple llvm-gcc-4.2)

I'd still vote for committing the change (unless it breaks linux builds) - we won't find out whether Inkscape can make use of the new multi-core features on OS X unless we enable it in trunk builds to allow testing.

Using autoconf's AC_OPENMP macro also allows to disable OpenMP support completely with './configure --disable-openmp' (which could be recommended for release builds on OS X if any version of Apple's gcc-4.2 turns out to be too unstable with openmp enabled):

$ ./configure --help | grep OpenMP
  --disable-openmp do not use OpenMP
$