Source code for gevent.util

# 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

[docs]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)
[docs]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 _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 frame.f_locals and frame.f_locals.get('gevent_threadpool_worker_idle'): 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)
[docs]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, }
[docs] 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
[docs] 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) self.__render_children(tree) 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
[docs] @classmethod def forest(cls): """ forest() -> sequence Return a sequence of `GreenletTree`, one for each running native thread. """ return list(cls._forest()[0].values())
[docs] @classmethod def current_tree(cls): """ current_tree() -> GreenletTree Returns the `GreenletTree` for the current thread. """ return cls._forest()[1]
class _FailedToSwitch(AssertionError): pass
[docs]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)