Hi, I'm using boost::bind for creating a thread group. My code shows this way: boost::thread_group l_threadgroup; for(std::size_t i=0; i < boost::thread::hardware_concurrency(); ++i) l_threadgroup .create_thread( boost::bind( &ncd<T>::multithread_deflate_symmetric, this, i ) ); The code runs within the class method "symmetric" and should be called from the self object the multithread_deflate_symmetric. My class "ncd" is a template class. I debug the code on a amd64 Gentoo Linux with valgrind 3.5 and get a "data race condition". Valgrind shows this message: ==6914== Possible data race during read of size 8 at 0x7fefff6d0 by thread #1 ==6914== at 0x4C2B138: ??? (in /usr/lib64/valgrind/ vgpreload_helgrind-amd64-linux.so) ==6914== by 0x6152B10: boost::thread::start_thread() (in /opt/ library/Boost/1.44/lib/libboost_thread.so.1.44.0) ==6914== by 0x414B50: boost::thread::thread<boost::_bi::bind_t<void, boost::_mfi::mf1<void, ncd<double>, unsigned long const&>, boost::_bi::list2<boost::_bi::value<ncd<double>*>, boost::_bi::value<unsigned long> > > >(boost::_bi::bind_t<void, boost::_mfi::mf1<void, ncd<double>, unsigned long const&>, boost::_bi::list2<boost::_bi::value<ncd<double>*>, boost::_bi::value<unsigned long> > >, boost::disable_if<boost::is_convertible<boost::_bi::bind_t<void, boost::_mfi::mf1<void, ncd<double>, unsigned long const&>, boost::_bi::list2<boost::_bi::value<ncd<double>*>, boost::_bi::value<unsigned long> > >&, boost::detail::thread_move_t<boost::_bi::bind_t<void, boost::_mfi::mf1<void, ncd<double>, unsigned long const&>, boost::_bi::list2<boost::_bi::value<ncd<double>*>, boost::_bi::value<unsigned long> > > > >, boost::thread::dummy*>::type) (in main) ==6914== by 0x419F4D: ncd<double>::symmetric(std::vector<std::string, std::allocator<std::string> > const&, bool const&) (in main) ==6914== by 0x40B10F: main (in main) ==6914== This conflicts with a previous write of size 8 by thread #2 ==6914== at 0x4C2B263: ??? (in /usr/lib64/valgrind/ vgpreload_helgrind-amd64-linux.so) Do I use boost::bind in the correct way? Thanks Phil