Tested on Ubuntu 19.10 with python 3.7.5 Crashing.
Backtrace gives Thread 3 "my_null_sink4" received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7fffe8939700 (LWP 7033)] 0x00007ffff265bed1 in gr::py_feval_ll::calleval(long) () from /usr/local/gnuradio/lib/python3/dist-packages/gnuradio/gr/_runtime_swig.so (gdb) bt #0 0x00007ffff265bed1 in gr::py_feval_ll::calleval(long) () from /usr/local/gnuradio/lib/python3/dist-packages/gnuradio/gr/_runtime_swig.so #1 0x00007ffff6caf2ea in gr::block_gateway_impl::work(int, std::vector<void const*, std::allocator<void const*> >&, std::vector<void*, std::allocator<void*> >&) () from /usr/local/gnuradio/lib/libgnuradio-runtime.so.3.9.0 #2 0x00007ffff6caf423 in gr::block_gateway_impl::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/gnuradio/lib/libgnuradio-runtime.so.3.9.0 #3 0x00007ffff6cad1a3 in gr::block_executor::run_one_iteration() () from /usr/local/gnuradio/lib/libgnuradio-runtime.so.3.9.0 #4 0x00007ffff6d03093 in gr::tpb_thread_body::tpb_thread_body(boost::shared_ptr<gr::block>, boost::shared_ptr<boost::barrier>, int) () from /usr/local/gnuradio/lib/libgnuradio-runtime.so.3.9.0 #5 0x00007ffff6cf498e in boost::detail::function::void_function_obj_invoker0<gr::thread::thread_body_wrapper<gr::tpb_container>, void>::invoke(boost::detail::function::function_buffer&) () from /usr/local/gnuradio/lib/libgnuradio-runtime.so.3.9.0 #6 0x00007ffff6d105c6 in boost::detail::thread_data<boost::function0<void> >::run() () from /usr/local/gnuradio/lib/libgnuradio-runtime.so.3.9.0 #7 0x00007ffff71f61b5 in ?? () from /usr/lib/x86_64-linux-gnu/libboost_thread.so.1.67.0 #8 0x00007ffff7d9c669 in start_thread (arg=<optimized out>) at pthread_create.c:479 #9 0x00007ffff7ed8323 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 By the way: trying the gnuradio version with pybind instead of swig crashes too. -- Volker