I have uploaded a bare minimum example that still has this problem:
sinusoid--> throtle --> (ON or OFF block) --> null sink
And here is all the output of gdb (it segfaults in unlock() ):
(gdb) backtrace
#0 0x00007ffff00b80a0 in volk_32fc_s32fc_multiply_32fc_a_sse3 ()
from /usr/local/lib64/libvolk.so.0.0.0
#1 0x00007ffff083910a in gr::blocks::multiply_const_cc_impl::work(int, std::vector<void const*, std::allocator<void const*> >&, std::vector<void*, std::allocator<void*> >&) ()
from /usr/local/lib64/libgnuradio-blocks-3.7.2git.so.0.0.0
#2 0x00007ffff0401fc7 in gr::sync_block::general_work(int, std::vector<int, std::allocator<int> >&, std::vector<void const*, std::allocator<void const*> >&, std::vector<void*, std::allocator<void*> >&) () from /usr/local/lib64/libgnuradio-runtime-3.7.2git.so.0.0.0
#3 0x00007ffff03caca8 in gr::block_executor::run_one_iteration() ()
from /usr/local/lib64/libgnuradio-runtime-3.7.2git.so.0.0.0
#4 0x00007ffff0410ee6 in gr::tpb_thread_body::tpb_thread_body(boost::shared_ptr<gr::block>, int) () from /usr/local/lib64/libgnuradio-runtime-3.7.2git.so.0.0.0
#5 0x00007ffff03ff38e in gr::tpb_container::operator()() ()
from /usr/local/lib64/libgnuradio-runtime-3.7.2git.so.0.0.0
#6 0x00007ffff03ff58e in gr::thread::thread_body_wrapper<gr::tpb_container>::operator()()
() from /usr/local/lib64/libgnuradio-runtime-3.7.2git.so.0.0.0
#7 0x00007ffff03b320f in boost::detail::thread_data<boost::function0<void> >::run() ()
from /usr/local/lib64/libgnuradio-runtime-3.7.2git.so.0.0.0
#8 0x0000003349a11629 in thread_proxy () from /lib64/libboost_thread-mt.so.1.50.0
#9 0x0000003340a07d15 in start_thread () from /lib64/libpthread.so.0
#10 0x000000333fef253d in clone () from /lib64/libc.so.6