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Python

# Copyright (c) 2009 Denis Bilenko. See LICENSE for details.
"""
Low-level utilities.
"""
from __future__ import absolute_import, print_function, division
import functools
import pprint
import sys
import traceback
from greenlet import getcurrent
from gevent._compat import perf_counter
from gevent._compat import PYPY
from gevent._compat import thread_mod_name
from gevent._util import _NONE
__all__ = [
'format_run_info',
'print_run_info',
'GreenletTree',
'wrap_errors',
'assert_switches',
]
# PyPy is very slow at formatting stacks
# for some reason.
_STACK_LIMIT = 20 if PYPY else None
def _noop():
return None
def _ready():
return False
class wrap_errors(object):
"""
Helper to make function return an exception, rather than raise it.
Because every exception that is unhandled by greenlet will be logged,
it is desirable to prevent non-error exceptions from leaving a greenlet.
This can done with a simple ``try/except`` construct::
def wrapped_func(*args, **kwargs):
try:
return func(*args, **kwargs)
except (TypeError, ValueError, AttributeError) as ex:
return ex
This class provides a shortcut to write that in one line::
wrapped_func = wrap_errors((TypeError, ValueError, AttributeError), func)
It also preserves ``__str__`` and ``__repr__`` of the original function.
"""
# QQQ could also support using wrap_errors as a decorator
def __init__(self, errors, func):
"""
Calling this makes a new function from *func*, such that it catches *errors* (an
:exc:`BaseException` subclass, or a tuple of :exc:`BaseException` subclasses) and
return it as a value.
"""
self.__errors = errors
self.__func = func
# Set __doc__, __wrapped__, etc, especially useful on Python 3.
functools.update_wrapper(self, func)
def __call__(self, *args, **kwargs):
func = self.__func
try:
return func(*args, **kwargs)
except self.__errors as ex:
return ex
def __str__(self):
return str(self.__func)
def __repr__(self):
return repr(self.__func)
def __getattr__(self, name):
return getattr(self.__func, name)
def print_run_info(thread_stacks=True, greenlet_stacks=True, limit=_NONE, file=None):
"""
Call `format_run_info` and print the results to *file*.
If *file* is not given, `sys.stderr` will be used.
.. versionadded:: 1.3b1
"""
lines = format_run_info(thread_stacks=thread_stacks,
greenlet_stacks=greenlet_stacks,
limit=limit)
file = sys.stderr if file is None else file
for l in lines:
print(l, file=file)
def format_run_info(thread_stacks=True,
greenlet_stacks=True,
limit=_NONE,
current_thread_ident=None):
"""
format_run_info(thread_stacks=True, greenlet_stacks=True, limit=None) -> [str]
Request information about the running threads of the current process.
This is a debugging utility. Its output has no guarantees other than being
intended for human consumption.
:keyword bool thread_stacks: If true, then include the stacks for
running threads.
:keyword bool greenlet_stacks: If true, then include the stacks for
running greenlets. (Spawning stacks will always be printed.)
Setting this to False can reduce the output volume considerably
without reducing the overall information if *thread_stacks* is true
and you can associate a greenlet to a thread (using ``thread_ident``
printed values).
:keyword int limit: If given, passed directly to `traceback.format_stack`.
If not given, this defaults to the whole stack under CPython, and a
smaller stack under PyPy.
:return: A sequence of text lines detailing the stacks of running
threads and greenlets. (One greenlet will duplicate one thread,
the current thread and greenlet. If there are multiple running threads,
the stack for the current greenlet may be incorrectly duplicated in multiple
greenlets.)
Extra information about
:class:`gevent.Greenlet` object will also be returned.
.. versionadded:: 1.3a1
.. versionchanged:: 1.3a2
Renamed from ``dump_stacks`` to reflect the fact that this
prints additional information about greenlets, including their
spawning stack, parent, locals, and any spawn tree locals.
.. versionchanged:: 1.3b1
Added the *thread_stacks*, *greenlet_stacks*, and *limit* params.
"""
if current_thread_ident is None:
from gevent import monkey
current_thread_ident = monkey.get_original(thread_mod_name, 'get_ident')()
lines = []
limit = _STACK_LIMIT if limit is _NONE else limit
_format_thread_info(lines, thread_stacks, limit, current_thread_ident)
_format_greenlet_info(lines, greenlet_stacks, limit)
return lines
def is_idle_threadpool_worker(frame):
return frame.f_locals and frame.f_locals.get('gevent_threadpool_worker_idle')
def _format_thread_info(lines, thread_stacks, limit, current_thread_ident):
import threading
threads = {th.ident: th for th in threading.enumerate()}
lines.append('*' * 80)
lines.append('* Threads')
thread = None
frame = None
for thread_ident, frame in sys._current_frames().items():
do_stacks = thread_stacks
lines.append("*" * 80)
thread = threads.get(thread_ident)
name = None
if not thread:
# Is it an idle threadpool thread? thread pool threads
# don't have a Thread object, they're low-level
if is_idle_threadpool_worker(frame):
name = 'idle threadpool worker'
do_stacks = False
else:
name = thread.name
if getattr(thread, 'gevent_monitoring_thread', None):
name = repr(thread.gevent_monitoring_thread())
if current_thread_ident == thread_ident:
name = '%s) (CURRENT' % (name,)
lines.append('Thread 0x%x (%s)\n' % (thread_ident, name))
if do_stacks:
lines.append(''.join(traceback.format_stack(frame, limit)))
elif not thread_stacks:
lines.append('\t...stack elided...')
# We may have captured our own frame, creating a reference
# cycle, so clear it out.
del thread
del frame
del lines
del threads
def _format_greenlet_info(lines, greenlet_stacks, limit):
# Use the gc module to inspect all objects to find the greenlets
# since there isn't a global registry
lines.append('*' * 80)
lines.append('* Greenlets')
lines.append('*' * 80)
for tree in sorted(GreenletTree.forest(),
key=lambda t: '' if t.is_current_tree else repr(t.greenlet)):
lines.append("---- Thread boundary")
lines.extend(tree.format_lines(details={
# greenlets from other threads tend to have their current
# frame just match our current frame, which is not helpful,
# so don't render their stack.
'running_stacks': greenlet_stacks if tree.is_current_tree else False,
'running_stack_limit': limit,
}))
del lines
dump_stacks = format_run_info
def _line(f):
@functools.wraps(f)
def w(self, *args, **kwargs):
r = f(self, *args, **kwargs)
self.lines.append(r)
return w
class _TreeFormatter(object):
UP_AND_RIGHT = '+'
HORIZONTAL = '-'
VERTICAL = '|'
VERTICAL_AND_RIGHT = '+'
DATA = ':'
label_space = 1
horiz_width = 3
indent = 1
def __init__(self, details, depth=0):
self.lines = []
self.depth = depth
self.details = details
if not details:
self.child_data = lambda *args, **kwargs: None
def deeper(self):
return type(self)(self.details, self.depth + 1)
@_line
def node_label(self, text):
return text
@_line
def child_head(self, label, right=VERTICAL_AND_RIGHT):
return (
' ' * self.indent
+ right
+ self.HORIZONTAL * self.horiz_width
+ ' ' * self.label_space
+ label
)
def last_child_head(self, label):
return self.child_head(label, self.UP_AND_RIGHT)
@_line
def child_tail(self, line, vertical=VERTICAL):
return (
' ' * self.indent
+ vertical
+ ' ' * self.horiz_width
+ line
)
def last_child_tail(self, line):
return self.child_tail(line, vertical=' ' * len(self.VERTICAL))
@_line
def child_data(self, data, data_marker=DATA): # pylint:disable=method-hidden
return ((
' ' * self.indent
+ (data_marker if not self.depth else ' ')
+ ' ' * self.horiz_width
+ ' ' * self.label_space
+ data
),)
def last_child_data(self, data):
return self.child_data(data, ' ')
def child_multidata(self, data):
# Remove embedded newlines
for l in data.splitlines():
self.child_data(l)
class GreenletTree(object):
"""
Represents a tree of greenlets.
In gevent, the *parent* of a greenlet is usually the hub, so this
tree is primarily arganized along the *spawning_greenlet* dimension.
This object has a small str form showing this hierarchy. The `format`
method can output more details. The exact output is unspecified but is
intended to be human readable.
Use the `forest` method to get the root greenlet trees for
all threads, and the `current_tree` to get the root greenlet tree for
the current thread.
"""
#: The greenlet this tree represents.
greenlet = None
#: Is this tree the root for the current thread?
is_current_tree = False
def __init__(self, greenlet):
self.greenlet = greenlet
self.child_trees = []
def add_child(self, tree):
if tree is self:
return
self.child_trees.append(tree)
@property
def root(self):
return self.greenlet.parent is None
def __getattr__(self, name):
return getattr(self.greenlet, name)
DEFAULT_DETAILS = {
'running_stacks': True,
'running_stack_limit': _STACK_LIMIT,
'spawning_stacks': True,
'locals': True,
}
def format_lines(self, details=True):
"""
Return a sequence of lines for the greenlet tree.
:keyword bool details: If true (the default),
then include more informative details in the output.
"""
if not isinstance(details, dict):
if not details:
details = {}
else:
details = self.DEFAULT_DETAILS.copy()
else:
params = details
details = self.DEFAULT_DETAILS.copy()
details.update(params)
tree = _TreeFormatter(details, depth=0)
lines = [l[0] if isinstance(l, tuple) else l
for l in self._render(tree)]
return lines
def format(self, details=True):
"""
Like `format_lines` but returns a string.
"""
lines = self.format_lines(details)
return '\n'.join(lines)
def __str__(self):
return self.format(False)
@staticmethod
def __render_tb(tree, label, frame, limit):
tree.child_data(label)
tb = ''.join(traceback.format_stack(frame, limit))
tree.child_multidata(tb)
@staticmethod
def __spawning_parent(greenlet):
return (getattr(greenlet, 'spawning_greenlet', None) or _noop)()
def __render_locals(self, tree):
# Defer the import to avoid cycles
from gevent.local import all_local_dicts_for_greenlet
gr_locals = all_local_dicts_for_greenlet(self.greenlet)
if gr_locals:
tree.child_data("Greenlet Locals:")
for (kind, idl), vals in gr_locals:
if not vals:
continue # not set in this greenlet; ignore it.
tree.child_data(" Local %s at %s" % (kind, hex(idl)))
tree.child_multidata(" " + pprint.pformat(vals))
def _render(self, tree):
label = repr(self.greenlet)
if not self.greenlet: # Not running or dead
# raw greenlets do not have ready
if getattr(self.greenlet, 'ready', _ready)():
label += '; finished'
if self.greenlet.value is not None:
label += ' with value ' + repr(self.greenlet.value)[:30]
elif getattr(self.greenlet, 'exception', None) is not None:
label += ' with exception ' + repr(self.greenlet.exception)
else:
label += '; not running'
tree.node_label(label)
tree.child_data('Parent: ' + repr(self.greenlet.parent))
if getattr(self.greenlet, 'gevent_monitoring_thread', None) is not None:
tree.child_data('Monitoring Thread:' + repr(self.greenlet.gevent_monitoring_thread()))
if self.greenlet and tree.details and tree.details['running_stacks']:
self.__render_tb(tree, 'Running:', self.greenlet.gr_frame,
tree.details['running_stack_limit'])
spawning_stack = getattr(self.greenlet, 'spawning_stack', None)
if spawning_stack and tree.details and tree.details['spawning_stacks']:
# We already placed a limit on the spawning stack when we captured it.
self.__render_tb(tree, 'Spawned at:', spawning_stack, None)
spawning_parent = self.__spawning_parent(self.greenlet)
tree_locals = getattr(self.greenlet, 'spawn_tree_locals', None)
if tree_locals and tree_locals is not getattr(spawning_parent, 'spawn_tree_locals', None):
tree.child_data('Spawn Tree Locals')
tree.child_multidata(pprint.pformat(tree_locals))
self.__render_locals(tree)
try:
self.__render_children(tree)
except RuntimeError: # pragma: no cover
# If the tree is exceptionally deep, we can hit the recursion error.
# Usually it's several levels down so we can make a print call.
# This came up in test__semaphore before TestSemaphoreFair
# was fixed.
print("When rendering children", *sys.exc_info())
return tree.lines
def __render_children(self, tree):
children = sorted(self.child_trees,
key=lambda c: (
# raw greenlets first. Note that we could be accessing
# minimal_ident for a hub from a different thread, which isn't
# technically thread safe.
getattr(c, 'minimal_ident', -1),
# running greenlets next
getattr(c, 'ready', _ready)(),
id(c.parent)))
for n, child in enumerate(children):
child_tree = child._render(tree.deeper())
head = tree.child_head
tail = tree.child_tail
data = tree.child_data
if n == len(children) - 1:
# last child does not get the line drawn
head = tree.last_child_head
tail = tree.last_child_tail
data = tree.last_child_data
head(child_tree.pop(0))
for child_data in child_tree:
if isinstance(child_data, tuple):
data(child_data[0])
else:
tail(child_data)
return tree.lines
@staticmethod
def _root_greenlet(greenlet):
while greenlet.parent is not None and not getattr(greenlet, 'greenlet_tree_is_root', False):
greenlet = greenlet.parent
return greenlet
@classmethod
def _forest(cls):
from gevent._greenlet_primitives import get_reachable_greenlets
main_greenlet = cls._root_greenlet(getcurrent())
trees = {} # greenlet -> GreenletTree
roots = {} # root greenlet -> GreenletTree
current_tree = roots[main_greenlet] = trees[main_greenlet] = cls(main_greenlet)
current_tree.is_current_tree = True
root_greenlet = cls._root_greenlet
glets = get_reachable_greenlets()
for ob in glets:
spawn_parent = cls.__spawning_parent(ob)
if spawn_parent is None:
# spawn parent is dead, or raw greenlet.
# reparent under the root.
spawn_parent = root_greenlet(ob)
if spawn_parent is root_greenlet(spawn_parent) and spawn_parent not in roots:
assert spawn_parent not in trees
trees[spawn_parent] = roots[spawn_parent] = cls(spawn_parent)
try:
parent_tree = trees[spawn_parent]
except KeyError: # pragma: no cover
parent_tree = trees[spawn_parent] = cls(spawn_parent)
try:
# If the child also happened to be a spawning parent,
# we could have seen it before; the reachable greenlets
# are in no particular order.
child_tree = trees[ob]
except KeyError:
trees[ob] = child_tree = cls(ob)
parent_tree.add_child(child_tree)
return roots, current_tree
@classmethod
def forest(cls):
"""
forest() -> sequence
Return a sequence of `GreenletTree`, one for each running
native thread.
"""
return list(cls._forest()[0].values())
@classmethod
def current_tree(cls):
"""
current_tree() -> GreenletTree
Returns the `GreenletTree` for the current thread.
"""
return cls._forest()[1]
class _FailedToSwitch(AssertionError):
pass
class assert_switches(object):
"""
A context manager for ensuring a block of code switches greenlets.
This performs a similar function as the :doc:`monitoring thread
</monitoring>`, but the scope is limited to the body of the with
statement. If the code within the body doesn't yield to the hub
(and doesn't raise an exception), then upon exiting the
context manager an :exc:`AssertionError` will be raised.
This is useful in unit tests and for debugging purposes.
:keyword float max_blocking_time: If given, the body is allowed
to block for up to this many fractional seconds before
an error is raised.
:keyword bool hub_only: If True, then *max_blocking_time* only
refers to the amount of time spent between switches into the
hub. If False, then it refers to the maximum time between
*any* switches. If *max_blocking_time* is not given, has no
effect.
Example::
# This will always raise an exception: nothing switched
with assert_switches():
pass
# This will never raise an exception; nothing switched,
# but it happened very fast
with assert_switches(max_blocking_time=1.0):
pass
.. versionadded:: 1.3
.. versionchanged:: 1.4
If an exception is raised, it now includes information about
the duration of blocking and the parameters of this object.
"""
hub = None
tracer = None
_entered = None
def __init__(self, max_blocking_time=None, hub_only=False):
self.max_blocking_time = max_blocking_time
self.hub_only = hub_only
def __enter__(self):
from gevent import get_hub
from gevent import _tracer
self.hub = hub = get_hub()
# TODO: We could optimize this to use the GreenletTracer
# installed by the monitoring thread, if there is one.
# As it is, we will chain trace calls back to it.
if not self.max_blocking_time:
self.tracer = _tracer.GreenletTracer()
elif self.hub_only:
self.tracer = _tracer.HubSwitchTracer(hub, self.max_blocking_time)
else:
self.tracer = _tracer.MaxSwitchTracer(hub, self.max_blocking_time)
self._entered = perf_counter()
self.tracer.monitor_current_greenlet_blocking()
return self
def __exit__(self, t, v, tb):
self.tracer.kill()
hub = self.hub; self.hub = None
tracer = self.tracer; self.tracer = None
# Only check if there was no exception raised, we
# don't want to hide anything
if t is not None:
return
did_block = tracer.did_block_hub(hub)
if did_block:
execution_time_s = perf_counter() - self._entered
active_greenlet = did_block[1]
report_lines = tracer.did_block_hub_report(hub, active_greenlet, {})
message = 'To the hub' if self.hub_only else 'To any greenlet'
message += ' in %.4f seconds' % (execution_time_s,)
max_block = self.max_blocking_time
message += ' (max allowed %.4f seconds)' % (max_block,) if max_block else ''
message += '\n'
message += '\n'.join(report_lines)
raise _FailedToSwitch(message)
def clear_stack_frames(frame):
"""Do our best to clear local variables in all frames in a stack."""
# On Python 3, frames have a .clear() method that can raise a RuntimeError.
while frame is not None:
try:
frame.clear()
except (RuntimeError, AttributeError):
pass
frame.f_locals.clear()
frame = frame.f_back