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Add multi-process debugging support using `pdbpp` 

This is the first step in addressing #113 and the initial support
of #130. Basically this allows (sub)processes to engage the `pdbpp`
debug machinery which read/writes the root actor's tty but only in
a FIFO semaphored way such that no two processes are using it
simultaneously. That means you can have multiple actors enter a trace or
crash and run the debugger in a sensible way without clobbering each
other's access to stdio. It required adding some "tear down hooks" to
a custom `pdbpp.Pdb` type such that we release a child's lock on the
parent on debugger exit (in this case when either of the "continue" or
"quit" commands are issued to the debugger console).

There's some code left commented in anticipation of full support for
issue #130 where we're need to actually capture and feed stdin to the
target (remote) actor which won't necessarily being running on the same
host.
debug_tests
Tyler Goodlet 2020-07-26 17:46:55 -04:00
parent e7ee0fec34
commit 8eb9a742dd
3 changed files with 135 additions and 55 deletions
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8
debugging/mp_debug.py
View File

@ -17,12 +17,14 @@ async def main():
"""
async with tractor.open_nursery() as n:
# portal = await n.run_in_actor('future_self', bubble)
portal = await n.run_in_actor('future_self', bail)
portal1 = await n.run_in_actor('bubble', bubble)
portal = await n.run_in_actor('bail', bail)
# await portal.result()
# await portal1.result()
# The ``async with`` will unblock here since the 'some_linguist'
# actor has completed its main task ``cellar_door``.
if __name__ == '__main__':
tractor.run(main, loglevel='info', debug_mode=True)
tractor.run(main, loglevel='critical', debug_mode=True)

8
tractor/_actor.py
View File

@ -126,13 +126,14 @@ async def _invoke(
task_status.started(cs)
await chan.send({'return': await coro, 'cid': cid})
except (Exception, trio.MultiError) as err:
log.exception("Actor errored:")
# NOTE: don't enter debug mode recursively after quitting pdb
if _state.debug_mode() and not isinstance(err, bdb.BdbQuit):
# Allow for pdb control in parent
from ._debug import post_mortem
log.exception("Actor crashed, entering debug mode:")
await post_mortem()
else:
log.exception("Actor crashed:")
# always ship errors back to caller
err_msg = pack_error(err)
@ -182,6 +183,7 @@ class Actor:
# Information about `__main__` from parent
_parent_main_data: Dict[str, str]
_parent_chan_cs: Optional[trio.CancelScope] = None
def __init__(
self,
@ -840,6 +842,8 @@ class Actor:
# for n in root.child_nurseries:
# n.cancel_scope.cancel()
self._parent_chan_cs.cancel()
async def _cancel_task(self, cid, chan):
"""Cancel a local task by call-id / channel.

174
tractor/_debug.py
View File

@ -1,9 +1,7 @@
"""
Multi-core debugging for da peeps!
"""
import pdb
import sys
import tty
from functools import partial
from typing import Awaitable, Tuple
@ -13,6 +11,16 @@ import trio
from .log import get_logger
try:
# wtf: only exported when installed in dev mode?
import pdbpp
except ImportError:
# pdbpp is installed in regular mode...
import pdb
assert pdb.xpm, "pdbpp is not installed?"
pdbpp = pdb
log = get_logger(__name__)
@ -25,56 +33,96 @@ _pdb_exit_patterns = tuple(
)
def subactoruid2proc(
actor: 'Actor', # noqa
uid: Tuple[str, str]
) -> trio.Process:
n = actor._actoruid2nursery[uid]
_, proc, _ = n._children[uid]
return proc
_pdb_release_hook = None
class PdbwTeardown(pdbpp.Pdb):
"""Add teardown hooks to the regular ``pdbpp.Pdb``.
"""
# TODO: figure out how to dissallow recursive .set_trace() entry
# since that'll cause deadlock for us.
def set_continue(self):
super().set_continue()
self.config.teardown(self)
def set_quit(self):
super().set_quit()
self.config.teardown(self)
class TractorConfig(pdbpp.DefaultConfig):
"""Custom ``pdbpp`` goodness.
"""
sticky_by_default = True
def teardown(self, _pdb):
_pdb_release_hook(_pdb)
# override the pdbpp config with our coolio one
pdbpp.Pdb.DefaultConfig = TractorConfig
# TODO: will be needed whenever we get to true remote debugging.
# XXX see https://github.com/goodboy/tractor/issues/130
# def subactoruid2proc(
# actor: 'Actor', # noqa
# uid: Tuple[str, str]
# ) -> trio.Process:
# n = actor._actoruid2nursery[uid]
# _, proc, _ = n._children[uid]
# return proc
# async def hijack_stdin():
# log.info(f"Hijacking stdin from {actor.uid}")
# trap std in and relay to subproc
# async_stdin = trio.wrap_file(sys.stdin)
# async with aclosing(async_stdin):
# async for msg in async_stdin:
# log.trace(f"Stdin input:\n{msg}")
# # encode to bytes
# bmsg = str.encode(msg)
# # relay bytes to subproc over pipe
# # await proc.stdin.send_all(bmsg)
# if bmsg in _pdb_exit_patterns:
# log.info("Closing stdin hijack")
# break
async def _hijack_stdin_relay_to_child(
subactor_uid: Tuple[str, str]
) -> None:
actor = tractor.current_actor()
proc = subactoruid2proc(actor, subactor_uid)
debug_lock = actor.statespace.setdefault(
'_debug_lock', trio.StrictFIFOLock()
)
# nlb = []
log.debug(f"Actor {subactor_uid} is waiting on stdin hijack lock")
await debug_lock.acquire()
log.warning(f"Actor {subactor_uid} acquired stdin hijack lock")
async def hijack_stdin():
log.info(f"Hijacking stdin from {actor.uid}")
# try:
# # disable cooked mode
# fd = sys.stdin.fileno()
# old = tty.tcgetattr(fd)
# tty.setcbreak(fd)
# TODO: when we get to true remote debugging
# this will deliver stdin data
try:
# indicate to child that we've locked stdio
yield 'Locked'
# trap std in and relay to subproc
async_stdin = trio.wrap_file(sys.stdin)
# wait for cancellation of stream by child
await trio.sleep_forever()
async with aclosing(async_stdin):
# while True:
async for msg in async_stdin:
log.trace(f"Stdin input:\n{msg}")
# nlb.append(msg)
# encode to bytes
bmsg = str.encode(msg)
# TODO: for remote debugging schedule hijacking in root scope
# (see above)
# actor._root_nursery.start_soon(hijack_stdin)
# relay bytes to subproc over pipe
await proc.stdin.send_all(bmsg)
# line = str.encode(''.join(nlb))
# print(line)
if bmsg in _pdb_exit_patterns:
log.info("Closing stdin hijack")
break
# finally:
# tty.tcsetattr(fd, tty.TCSAFLUSH, old)
# schedule hijacking in root scope
actor._root_nursery.start_soon(hijack_stdin)
finally:
if debug_lock.locked():
debug_lock.release()
log.debug(f"Actor {subactor_uid} released stdin hijack lock")
# XXX: We only make this sync in case someone wants to
@ -84,35 +132,61 @@ def _breakpoint(debug_func) -> Awaitable[None]:
in subactors.
"""
actor = tractor.current_actor()
do_unlock = trio.Event()
async def wait_for_parent_stdin_hijack():
log.debug('Breakpoint engaged!')
async def wait_for_parent_stdin_hijack(
task_status=trio.TASK_STATUS_IGNORED
):
# TODO: need a more robust check for the "root" actor
if actor._parent_chan:
async with tractor._portal.open_portal(
actor._parent_chan,
start_msg_loop=False,
shield=True,
) as portal:
# with trio.fail_after(1):
await portal.run(
agen = await portal.run(
'tractor._debug',
'_hijack_stdin_relay_to_child',
subactor_uid=actor.uid,
)
async with aclosing(agen):
async for val in agen:
assert val == 'Locked'
task_status.started()
with trio.CancelScope(shield=True):
await do_unlock.wait()
# trigger cancellation of remote stream
break
log.debug(f"Child {actor} released parent stdio lock")
def unlock(_pdb):
do_unlock.set()
global _pdb_release_hook
_pdb_release_hook = unlock
async def _bp():
# this must be awaited by caller
await actor._root_nursery.start(
wait_for_parent_stdin_hijack
)
# block here one frame up where ``breakpoint()``
# was awaited and begin handling stdin
debug_func(actor)
# this must be awaited by caller
return wait_for_parent_stdin_hijack()
# return wait_for_parent_stdin_hijack()
return _bp()
def _set_trace(actor):
pdb.set_trace(
header=f"\nAttaching pdb to actor: {actor.uid}\n",
# start 2 levels up
log.critical(f"\nAttaching pdb to actor: {actor.uid}\n")
PdbwTeardown().set_trace(
# start 2 levels up in user code
frame=sys._getframe().f_back.f_back,
)
@ -125,7 +199,7 @@ breakpoint = partial(
def _post_mortem(actor):
log.error(f"\nAttaching to pdb in crashed actor: {actor.uid}\n")
pdb.post_mortem()
pdbpp.xpm(Pdb=PdbwTeardown)
post_mortem = partial(