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""" This module contains utility functions to construct and manipulate counting
data structures for frames.
When performing statistical profiling we obtain many call stacks. We aggregate
these call stacks into data structures that maintain counts of how many times
each function in that call stack has been called. Because these stacks will
overlap this aggregation counting structure forms a tree, such as is commonly
visualized by profiling tools.
We represent this tree as a nested dictionary with the following form:
{
'identifier': 'root',
'description': 'A long description of the line of code being run.',
'count': 10 # the number of times we have seen this line
'children': { # callers of this line. Recursive dicts
'ident-b': {'description': ...
'identifier': 'ident-a',
'count': ...
'children': {...}},
'ident-b': {'description': ...
'identifier': 'ident-b',
'count': ...
'children': {...}}}
}
"""
from __future__ import annotations
import bisect
import dis
import linecache
import sys
import threading
from collections import defaultdict, deque
from collections.abc import Callable, Collection
from time import sleep
from types import FrameType
from typing import Any
import tlz as toolz
from dask.utils import format_time, parse_timedelta
from distributed.metrics import time
from distributed.utils import color_of
#: This lock can be acquired to ensure that no instance of watch() is concurrently holding references to frames
lock = threading.Lock()
def identifier(frame: FrameType | None) -> str:
"""A string identifier from a frame
Strings are cheaper to use as indexes into dicts than tuples or dicts
"""
if frame is None:
return "None"
else:
return ";".join(
(
frame.f_code.co_name,
frame.f_code.co_filename,
str(frame.f_code.co_firstlineno),
)
)
def _f_lineno(frame: FrameType) -> int:
"""Work around some frames lacking an f_lineno
See: https://bugs.python.org/issue47085
"""
f_lineno = frame.f_lineno
if f_lineno is not None:
return f_lineno
f_lasti = frame.f_lasti
code = frame.f_code
prev_line = code.co_firstlineno
for start, next_line in dis.findlinestarts(code):
if f_lasti < start:
return prev_line
prev_line = next_line
return prev_line
def repr_frame(frame: FrameType) -> str:
"""Render a frame as a line for inclusion into a text traceback"""
co = frame.f_code
f_lineno = _f_lineno(frame)
text = f' File "{co.co_filename}", line {f_lineno}, in {co.co_name}'
line = linecache.getline(co.co_filename, f_lineno, frame.f_globals).lstrip()
return text + "\n\t" + line
def info_frame(frame: FrameType) -> dict[str, Any]:
co = frame.f_code
f_lineno = _f_lineno(frame)
line = linecache.getline(co.co_filename, f_lineno, frame.f_globals).lstrip()
return {
"filename": co.co_filename,
"name": co.co_name,
"line_number": f_lineno,
"line": line,
}
def process(
frame: FrameType,
child: object | None,
state: dict[str, Any],
*,
stop: str | None = None,
omit: Collection[str] = (),
depth: int | None = None,
) -> dict[str, Any] | None:
"""Add counts from a frame stack onto existing state
This recursively adds counts to the existing state dictionary and creates
new entries for new functions.
Parameters
----------
frame:
The frame to process onto the state
child:
For internal use only
state:
The profile state to accumulate this frame onto, see ``create``
stop:
Filename suffix that should stop processing if we encounter it
omit:
Filenames that we should omit from processing
depth:
For internal use only, how deep we are in the call stack
Used to prevent stack overflow
Examples
--------
>>> import sys, threading
>>> ident = threading.get_ident() # replace with your thread of interest
>>> frame = sys._current_frames()[ident]
>>> state = create()
>>> process(frame, None, state)
>>> state
{'count': 1,
'identifier': 'root',
'description': 'root',
'children': {'...'}}
See also
--------
create
merge
"""
if depth is None:
depth = sys.getrecursionlimit() - 50
if depth <= 0:
return None
if any(frame.f_code.co_filename.endswith(o) for o in omit):
return None
prev = frame.f_back
if prev is not None and (
stop is None or not prev.f_code.co_filename.endswith(stop)
):
new_state = process(prev, frame, state, stop=stop, depth=depth - 1)
if new_state is None:
return None
state = new_state
ident = identifier(frame)
try:
d = state["children"][ident]
except KeyError:
d = {
"count": 0,
"description": info_frame(frame),
"children": {},
"identifier": ident,
}
state["children"][ident] = d
state["count"] += 1
if child is not None:
return d
else:
d["count"] += 1
return None
def merge(*args: dict[str, Any]) -> dict[str, Any]:
"""Merge multiple frame states together"""
if not args:
return create()
s = {arg["identifier"] for arg in args}
if len(s) != 1: # pragma: no cover
raise ValueError(f"Expected identifiers, got {s}")
children = defaultdict(list)
for arg in args:
for child in arg["children"]:
children[child].append(arg["children"][child])
try:
children_dict = {k: merge(*v) for k, v in children.items()}
except RecursionError: # pragma: no cover
children_dict = {}
count = sum(arg["count"] for arg in args)
return {
"description": args[0]["description"],
"children": children_dict,
"count": count,
"identifier": args[0]["identifier"],
}
def create() -> dict[str, Any]:
return {
"count": 0,
"children": {},
"identifier": "root",
"description": {"filename": "", "name": "", "line_number": 0, "line": ""},
}
def call_stack(frame: FrameType) -> list[str]:
"""Create a call text stack from a frame
Returns
-------
list of strings
"""
L = []
cur_frame: FrameType | None = frame
while cur_frame:
L.append(repr_frame(cur_frame))
cur_frame = cur_frame.f_back
return L[::-1]
def plot_data(state, profile_interval=0.010):
"""Convert a profile state into data useful by Bokeh
See Also
--------
plot_figure
distributed.bokeh.components.ProfilePlot
"""
starts = []
stops = []
heights = []
widths = []
colors = []
states = []
times = []
filenames = []
lines = []
line_numbers = []
names = []
def traverse(state, start, stop, height):
if not state["count"]:
return
starts.append(start)
stops.append(stop)
heights.append(height)
width = stop - start
widths.append(width)
states.append(state)
times.append(format_time(state["count"] * profile_interval))
desc = state["description"]
filenames.append(desc["filename"])
lines.append(desc["line"])
line_numbers.append(desc["line_number"])
names.append(desc["name"])
try:
fn = desc["filename"]
except IndexError: # pragma: no cover
colors.append("gray")
else:
if fn == "<low-level>": # pragma: no cover
colors.append("lightgray")
else:
colors.append(color_of(fn))
delta = (stop - start) / state["count"]
x = start
for _, child in state["children"].items():
width = child["count"] * delta
traverse(child, x, x + width, height + 1)
x += width
traverse(state, 0, 1, 0)
percentages = [f"{100 * w:.1f}%" for w in widths]
return {
"left": starts,
"right": stops,
"bottom": heights,
"width": widths,
"top": [x + 1 for x in heights],
"color": colors,
"states": states,
"filename": filenames,
"line": lines,
"line_number": line_numbers,
"name": names,
"time": times,
"percentage": percentages,
}
def _watch(
thread_id: int,
log: deque[tuple[float, dict[str, Any]]], # [(timestamp, output of create()), ...]
interval: float,
cycle: float,
omit: Collection[str],
stop: Callable[[], bool],
) -> None:
recent = create()
last = time()
while not stop():
if time() > last + cycle:
recent = create()
with lock:
log.append((time(), recent))
last = time()
try:
frame = sys._current_frames()[thread_id]
except KeyError:
return
process(frame, None, recent, omit=omit)
del frame
sleep(interval)
def watch(
thread_id: int | None = None,
interval: str = "20ms",
cycle: str = "2s",
maxlen: int = 1000,
omit: Collection[str] = (),
stop: Callable[[], bool] = lambda: False,
) -> deque[tuple[float, dict[str, Any]]]:
"""Gather profile information on a particular thread
This starts a new thread to watch a particular thread and returns a deque
that holds periodic profile information.
Parameters
----------
thread_id : int, optional
Defaults to current thread
interval : str
Time per sample
cycle : str
Time per refreshing to a new profile state
maxlen : int
Passed onto deque, maximum number of periods
omit : collection of str
Don't include entries whose filename includes any of these substrings
stop : callable
Function to call to see if we should stop. It must
accept no arguments and return a bool (True to stop,
False to continue).
Returns
-------
deque of tuples:
- timestamp
- dict[str, Any] (output of ``create()``)
"""
log: deque[tuple[float, dict[str, Any]]] = deque(maxlen=maxlen)
thread = threading.Thread(
target=_watch,
name="Profile",
kwargs={
"thread_id": thread_id or threading.get_ident(),
"interval": parse_timedelta(interval),
"cycle": parse_timedelta(cycle),
"log": log,
"omit": omit,
"stop": stop,
},
)
thread.daemon = True
thread.start()
return log
def get_profile(history, recent=None, start=None, stop=None, key=None):
"""Collect profile information from a sequence of profile states
Parameters
----------
history : Sequence[Tuple[time, Dict]]
A list or deque of profile states
recent : dict
The most recent accumulating state
start : time
stop : time
"""
if start is None:
istart = 0
else:
istart = bisect.bisect_left(history, (start,))
if stop is None:
istop = None
else:
istop = bisect.bisect_right(history, (stop,)) + 1
if istop >= len(history):
istop = None # include end
if istart == 0 and istop is None:
history = list(history)
else:
iistop = len(history) if istop is None else istop
history = [history[i] for i in range(istart, iistop)]
prof = merge(*toolz.pluck(1, history))
if not history:
return create()
if recent:
prof = merge(prof, recent)
return prof
def plot_figure(data, **kwargs):
"""Plot profile data using Bokeh
This takes the output from the function ``plot_data`` and produces a Bokeh
figure
See Also
--------
plot_data
"""
from bokeh.models import HoverTool
from bokeh.plotting import ColumnDataSource, figure
if "states" in data:
data = toolz.dissoc(data, "states")
source = ColumnDataSource(data=data)
fig = figure(tools="tap,box_zoom,xwheel_zoom,reset", **kwargs)
r = fig.quad(
"left",
"right",
"top",
"bottom",
color="color",
line_color="black",
line_width=2,
source=source,
)
r.selection_glyph = None
r.nonselection_glyph = None
hover = HoverTool(
point_policy="follow_mouse",
tooltips="""
<div>
<span style="font-size: 14px; font-weight: bold;">Name:</span>&nbsp;
<span style="font-size: 10px; font-family: Monaco, monospace;">@name</span>
</div>
<div>
<span style="font-size: 14px; font-weight: bold;">Filename:</span>&nbsp;
<span style="font-size: 10px; font-family: Monaco, monospace;">@filename</span>
</div>
<div>
<span style="font-size: 14px; font-weight: bold;">Line number:</span>&nbsp;
<span style="font-size: 10px; font-family: Monaco, monospace;">@line_number</span>
</div>
<div>
<span style="font-size: 14px; font-weight: bold;">Line:</span>&nbsp;
<span style="font-size: 10px; font-family: Monaco, monospace;">@line</span>
</div>
<div>
<span style="font-size: 14px; font-weight: bold;">Time:</span>&nbsp;
<span style="font-size: 10px; font-family: Monaco, monospace;">@time</span>
</div>
<div>
<span style="font-size: 14px; font-weight: bold;">Percentage:</span>&nbsp;
<span style="font-size: 10px; font-family: Monaco, monospace;">@percentage</span>
</div>
""",
)
fig.add_tools(hover)
fig.xaxis.visible = False
fig.yaxis.visible = False
fig.grid.visible = False
return fig, source
def _remove_py_stack(frames):
for entry in frames:
if entry.is_python:
break
yield entry
def llprocess( # type: ignore[no-untyped-def]
frames,
child: object | None,
state: dict[str, Any] | None,
) -> dict[str, Any] | None:
"""Add counts from low level profile information onto existing state
This uses the ``stacktrace`` module to collect low level stack trace
information and place it onto the given state.
It is configured with the ``distributed.worker.profile.low-level`` config
entry.
See Also
--------
process
ll_get_stack
"""
if not frames:
return None
frame = frames.pop()
if frames:
state = llprocess(frames, frame, state)
assert state
addr = hex(frame.addr - frame.offset)
ident = ";".join(map(str, (frame.name, "<low-level>", addr)))
try:
d = state["children"][ident]
except KeyError:
d = {
"count": 0,
"description": {
"filename": "<low-level>",
"name": frame.name,
"line_number": 0,
"line": str(frame),
},
"children": {},
"identifier": ident,
}
state["children"][ident] = d
state["count"] += 1
if child is not None:
return d
else:
d["count"] += 1
return None
def ll_get_stack(tid):
"""Collect low level stack information from thread id"""
from stacktrace import get_thread_stack
frames = get_thread_stack(tid, show_python=False)
llframes = list(_remove_py_stack(frames))[::-1]
return llframes