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@mskrajnowski
Last active December 6, 2018 11:20
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Flamegraph django middleware
"""
Django middleware for generating request flame graphs.
Requires the flamegraph.pl perl script:
https://github.com/brendangregg/FlameGraph/blob/master/flamegraph.pl
Installation:
1. Create a directory for flame graphs
2. Copy the flamegraph.pl script to it
3. Add the FLAMES_DIR django setting
4. Add the flames.FlamesMiddleware to MIDDLEWARE_CLASSES
Usage:
To generate a flame graph just append ?flames to the requested url.
Middleware will create an svg in the FLAMES_DIR with the current timestamp.
Uncomment line 88 to automatically open the svg in a new google chrome tab.
"""
import os
import subprocess
import sys
import threading
import time
import traceback
from datetime import datetime
from xml.dom.minidom import Text
from django.conf import settings
FLAMES_DIR = os.path.abspath(settings.FLAMES_DIR)
FLAMEGRAPH_SCRIPT_PATH = os.path.join(FLAMES_DIR, 'flamegraph.pl')
def get_module_name(module_path):
for path in sys.path:
path = path or os.getcwd()
if module_path.startswith(path):
rel_path = module_path[len(path) + 1:]
return (
rel_path
.replace(u'/__init__.py', u'')
.replace(u'/', '.')
.replace(u'.py', u'')
.strip()
)
return module_path
def write_samples(file, samples):
for _, frame in samples:
stack = traceback.extract_stack(frame)
frame_strings = (
func_name + u'@' + get_module_name(module_path)
for module_path, _, func_name, _ in stack
)
stack_string = u';'.join(frame_strings)
file.write(u'{} {}\n'.format(stack_string, 1))
def write_flames(logger, title='flames'):
base_path = os.path.join(
FLAMES_DIR,
datetime.now().strftime('%Y-%m-%dT%H:%M:%S'),
)
out_txt_path = base_path + '.txt'
out_svg_path = base_path + '.svg'
title_element = Text()
title_element.data = title
title_xml = title_element.toxml()
with open(out_txt_path, 'w') as out_txt:
write_samples(out_txt, logger.samples)
with open(out_svg_path, 'w') as out_svg:
subprocess.call(
[
'perl', FLAMEGRAPH_SCRIPT_PATH, out_txt_path,
'--title', title_xml,
],
stdout=out_svg
)
# subprocess.call(['google-chrome', 'file://' + out_svg_path])
class StackLogger(object):
def __init__(self, thread_id, interval=0.001):
super(StackLogger, self).__init__()
self.thread_id = thread_id
self.interval = interval
self.should_stop = False
self.samples = []
self.started = threading.Event()
self.thread = threading.Thread(target=self.run)
def run(self):
start_time = time.time()
self.samples = []
self.started.set()
while not self.should_stop:
frame_start = time.clock()
timestamp = time.time() - start_time
frame = sys._current_frames()[self.thread_id]
self.samples.append((timestamp, frame))
frame_dt = time.clock() - frame_start
time.sleep(max(0, self.interval - frame_dt))
def start(self):
self.started.clear()
self.should_stop = False
self.thread.start()
self.started.wait()
def stop(self):
self.should_stop = True
self.thread.join()
class FlamesMiddleware(object):
def process_request(self, request):
if settings.DEBUG and 'flames' in request.GET:
logger = StackLogger(threading.current_thread().ident)
logger.start()
request._stack_logger = logger
def process_response(self, request, response):
if settings.DEBUG and hasattr(request, '_stack_logger'):
logger = request._stack_logger
logger.stop()
url = request.build_absolute_uri()
write_flames(logger, title=url)
return response
@elmehalawi
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Use this fork for >= django 1.10.

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