forked from goodboy/tractor
1
0
Fork 0
tractor/examples/debugging/sync_bp.py

170 lines
5.6 KiB
Python

from functools import partial
import time
import trio
import tractor
# TODO: only import these when not running from test harness?
# can we detect `pexpect` usage maybe?
# from tractor.devx._debug import (
# get_lock,
# get_debug_req,
# )
def sync_pause(
use_builtin: bool = False,
error: bool = False,
hide_tb: bool = True,
pre_sleep: float|None = None,
):
if pre_sleep:
time.sleep(pre_sleep)
if use_builtin:
breakpoint(hide_tb=hide_tb)
else:
# TODO: maybe for testing some kind of cm style interface
# where the `._set_trace()` call doesn't happen until block
# exit?
# assert get_lock().ctx_in_debug is None
# assert get_debug_req().repl is None
tractor.pause_from_sync()
# assert get_debug_req().repl is None
if error:
raise RuntimeError('yoyo sync code error')
@tractor.context
async def start_n_sync_pause(
ctx: tractor.Context,
):
actor: tractor.Actor = tractor.current_actor()
# sync to parent-side task
await ctx.started()
print(f'Entering `sync_pause()` in subactor: {actor.uid}\n')
sync_pause()
print(f'Exited `sync_pause()` in subactor: {actor.uid}\n')
async def main() -> None:
async with (
tractor.open_nursery(
debug_mode=True,
maybe_enable_greenback=True,
enable_stack_on_sig=True,
# loglevel='warning',
# loglevel='devx',
) as an,
trio.open_nursery() as tn,
):
# just from root task
sync_pause()
p: tractor.Portal = await an.start_actor(
'subactor',
enable_modules=[__name__],
# infect_asyncio=True,
debug_mode=True,
)
# TODO: 3 sub-actor usage cases:
# -[x] via a `.open_context()`
# -[ ] via a `.run_in_actor()` call
# -[ ] via a `.run()`
# -[ ] via a `.to_thread.run_sync()` in subactor
async with p.open_context(
start_n_sync_pause,
) as (ctx, first):
assert first is None
# TODO: handle bg-thread-in-root-actor special cases!
#
# there are a couple very subtle situations possible here
# and they are likely to become more important as cpython
# moves to support no-GIL.
#
# Cases:
# 1. root-actor bg-threads that call `.pause_from_sync()`
# whilst an in-tree subactor also is using ` .pause()`.
# |_ since the root-actor bg thread can not
# `Lock._debug_lock.acquire_nowait()` without running
# a `trio.Task`, AND because the
# `PdbREPL.set_continue()` is called from that
# bg-thread, we can not `._debug_lock.release()`
# either!
# |_ this results in no actor-tree `Lock` being used
# on behalf of the bg-thread and thus the subactor's
# task and the thread trying to to use stdio
# simultaneously which results in the classic TTY
# clobbering!
#
# 2. mutiple sync-bg-threads that call
# `.pause_from_sync()` where one is scheduled via
# `Nursery.start_soon(to_thread.run_sync)` in a bg
# task.
#
# Due to the GIL, the threads never truly try to step
# through the REPL simultaneously, BUT their `logging`
# and traceback outputs are interleaved since the GIL
# (seemingly) on every REPL-input from the user
# switches threads..
#
# Soo, the context switching semantics of the GIL
# result in a very confusing and messy interaction UX
# since eval and (tb) print output is NOT synced to
# each REPL-cycle (like we normally make it via
# a `.set_continue()` callback triggering the
# `Lock.release()`). Ideally we can solve this
# usability issue NOW because this will of course be
# that much more important when eventually there is no
# GIL!
# XXX should cause double REPL entry and thus TTY
# clobbering due to case 1. above!
tn.start_soon(
partial(
trio.to_thread.run_sync,
partial(
sync_pause,
use_builtin=False,
# pre_sleep=0.5,
),
abandon_on_cancel=True,
thread_name='start_soon_root_bg_thread',
)
)
await tractor.pause()
# XXX should cause double REPL entry and thus TTY
# clobbering due to case 2. above!
await trio.to_thread.run_sync(
partial(
sync_pause,
# NOTE this already works fine since in the new
# thread the `breakpoint()` built-in is never
# overloaded, thus NO locking is used, HOWEVER
# the case 2. from above still exists!
use_builtin=True,
),
# TODO: with this `False` we can hang!??!
# abandon_on_cancel=False,
abandon_on_cancel=True,
thread_name='inline_root_bg_thread',
)
await ctx.cancel()
# TODO: case where we cancel from trio-side while asyncio task
# has debugger lock?
await p.cancel_actor()
if __name__ == '__main__':
trio.run(main)