Use a task nursery in the subactor to spawn tasks which cancel the IPC
channel mid stream to simulate the most concurrent case we're likely to
see. Make `main()` accept a `debug_mode: bool` for parametrization. Fill
out detailed comments/docs on this example.
Finally! I think this may be the root issue we've been seeing in
production in a client project.
No idea yet why this is happening but the fault-causing sequence seems
to be:
- `.open_context()` in a child actor
- enter the debugger via `tractor.breakpoint()`
- continue from that entry via `c` command in REPL
- raise an error just after inside the context task's body
Looking at logging it appears as though the child thinks it has the tty
but no input is accepted on the REPL and a further `ctrl-c` results in
some teardown but also a further hang where both parent and child become
unresponsive..
With the new fixes to the trio spawner we can expect that both root
*and* depth > 1 nursery owning actors will now not clobber any children
that are in debug (either via breakpoint or through crashing). The tests
changed now include more checks which ensure the 2nd level parent-ish
actors also bubble up through into `pdb` and don't kill any of their
(crashed) children before they're done themselves debugging.
This is a draft of the `tractor` way to implement the example from the
"processs pool" in the stdlib's `concurrent.futures` docs:
https://docs.python.org/3/library/concurrent.futures.html#processpoolexecutor-example
Our runtime is of course slower to startup but once up we of course get
the same performance, this confirms that we need to focus some effort
not on warm up and teardown times. The mp forkserver method definitely
improves startup delay; rolling our own will likely be a good hot spot
to play with.
What's really nice is our implementation is done in approx 10th the code ;)
Also, do we want offer and interface that yields results as they arrive?
Relates to #175
Tyler Goodlet