(gdb) bt
#0  0x00007f31a596940d in poll () from /nix/store/gwl3ppqj4i730nhd4f50ncl5jc4n97ks-glibc-2.23/lib/libc.so.6
#1  0x00007f31a64db2b7 in (anonymous namespace)::wait_fd(int, bool, timeval*) () from /nix/store/zclq81axk9yg3rv4xlimq7vsqik5a2aw-libpqxx-4.0.1/lib/libpqxx-4.0.so
#2  0x00007f31a64dc4c1 in pqxx::internal::wait_read(pg_conn const*, long, long) () from /nix/store/zclq81axk9yg3rv4xlimq7vsqik5a2aw-libpqxx-4.0.1/lib/libpqxx-4.0.so
#3  0x00007f31a64e0246 in pqxx::connection_base::await_notification(long, long) () from /nix/store/zclq81axk9yg3rv4xlimq7vsqik5a2aw-libpqxx-4.0.1/lib/libpqxx-4.0.so
#4  0x00000000004196c4 in State::run(unsigned int) ()
#5  0x000000000041a272 in main::{lambda()#1}::operator()() const ()
#6  0x00007f31a7771802 in nix::handleExceptions(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::function<void ()>) ()
   from /nix/store/r3blahkd7z58xsdbgdyl5hbfgaqn0var-nix-1.12pre4523_3b81b26/lib/libnixmain.so
#7  0x000000000040eada in main ()