GDB can do that already. (gdb) help set scheduler-locking Set mode for locking scheduler during execution. off == no locking (threads may preempt at

GDB can do that already. (gdb) help set scheduler-locking Set mode for locking scheduler during execution. off == no locking (threads may preempt at any time) on == full locking (no thread except the current thread may run) step == scheduler locked during every single-step operation. In this mode, no other thread may run during a step command. Other threads may run while stepping over a function call ('next').