I\'ve recently become interested in algorithms and have begun exploring them by writing a naive implementation and then optimizing it in various ways.
I\'m already f
Python 3.4 includes a new module: tracemalloc. It provides detailed statistics about which code is allocating the most memory. Here's an example that displays the top three lines allocating memory.
from collections import Counter
import linecache
import os
import tracemalloc
def display_top(snapshot, key_type='lineno', limit=3):
snapshot = snapshot.filter_traces((
tracemalloc.Filter(False, "<frozen importlib._bootstrap>"),
tracemalloc.Filter(False, "<unknown>"),
))
top_stats = snapshot.statistics(key_type)
print("Top %s lines" % limit)
for index, stat in enumerate(top_stats[:limit], 1):
frame = stat.traceback[0]
# replace "/path/to/module/file.py" with "module/file.py"
filename = os.sep.join(frame.filename.split(os.sep)[-2:])
print("#%s: %s:%s: %.1f KiB"
% (index, filename, frame.lineno, stat.size / 1024))
line = linecache.getline(frame.filename, frame.lineno).strip()
if line:
print(' %s' % line)
other = top_stats[limit:]
if other:
size = sum(stat.size for stat in other)
print("%s other: %.1f KiB" % (len(other), size / 1024))
total = sum(stat.size for stat in top_stats)
print("Total allocated size: %.1f KiB" % (total / 1024))
tracemalloc.start()
counts = Counter()
fname = '/usr/share/dict/american-english'
with open(fname) as words:
words = list(words)
for word in words:
prefix = word[:3]
counts[prefix] += 1
print('Top prefixes:', counts.most_common(3))
snapshot = tracemalloc.take_snapshot()
display_top(snapshot)
And here are the results:
Top prefixes: [('con', 1220), ('dis', 1002), ('pro', 809)]
Top 3 lines
#1: scratches/memory_test.py:37: 6527.1 KiB
words = list(words)
#2: scratches/memory_test.py:39: 247.7 KiB
prefix = word[:3]
#3: scratches/memory_test.py:40: 193.0 KiB
counts[prefix] += 1
4 other: 4.3 KiB
Total allocated size: 6972.1 KiB
That example is great when the memory is still being held at the end of the calculation, but sometimes you have code that allocates a lot of memory and then releases it all. It's not technically a memory leak, but it's using more memory than you think it should. How can you track memory usage when it all gets released? If it's your code, you can probably add some debugging code to take snapshots while it's running. If not, you can start a background thread to monitor memory usage while the main thread runs.
Here's the previous example where the code has all been moved into the count_prefixes()
function. When that function returns, all the memory is released. I also added some sleep()
calls to simulate a long-running calculation.
from collections import Counter
import linecache
import os
import tracemalloc
from time import sleep
def count_prefixes():
sleep(2) # Start up time.
counts = Counter()
fname = '/usr/share/dict/american-english'
with open(fname) as words:
words = list(words)
for word in words:
prefix = word[:3]
counts[prefix] += 1
sleep(0.0001)
most_common = counts.most_common(3)
sleep(3) # Shut down time.
return most_common
def main():
tracemalloc.start()
most_common = count_prefixes()
print('Top prefixes:', most_common)
snapshot = tracemalloc.take_snapshot()
display_top(snapshot)
def display_top(snapshot, key_type='lineno', limit=3):
snapshot = snapshot.filter_traces((
tracemalloc.Filter(False, "<frozen importlib._bootstrap>"),
tracemalloc.Filter(False, "<unknown>"),
))
top_stats = snapshot.statistics(key_type)
print("Top %s lines" % limit)
for index, stat in enumerate(top_stats[:limit], 1):
frame = stat.traceback[0]
# replace "/path/to/module/file.py" with "module/file.py"
filename = os.sep.join(frame.filename.split(os.sep)[-2:])
print("#%s: %s:%s: %.1f KiB"
% (index, filename, frame.lineno, stat.size / 1024))
line = linecache.getline(frame.filename, frame.lineno).strip()
if line:
print(' %s' % line)
other = top_stats[limit:]
if other:
size = sum(stat.size for stat in other)
print("%s other: %.1f KiB" % (len(other), size / 1024))
total = sum(stat.size for stat in top_stats)
print("Total allocated size: %.1f KiB" % (total / 1024))
main()
When I run that version, the memory usage has gone from 6MB down to 4KB, because the function released all its memory when it finished.
Top prefixes: [('con', 1220), ('dis', 1002), ('pro', 809)]
Top 3 lines
#1: collections/__init__.py:537: 0.7 KiB
self.update(*args, **kwds)
#2: collections/__init__.py:555: 0.6 KiB
return _heapq.nlargest(n, self.items(), key=_itemgetter(1))
#3: python3.6/heapq.py:569: 0.5 KiB
result = [(key(elem), i, elem) for i, elem in zip(range(0, -n, -1), it)]
10 other: 2.2 KiB
Total allocated size: 4.0 KiB
Now here's a version inspired by another answer that starts a second thread to monitor memory usage.
from collections import Counter
import linecache
import os
import tracemalloc
from datetime import datetime
from queue import Queue, Empty
from resource import getrusage, RUSAGE_SELF
from threading import Thread
from time import sleep
def memory_monitor(command_queue: Queue, poll_interval=1):
tracemalloc.start()
old_max = 0
snapshot = None
while True:
try:
command_queue.get(timeout=poll_interval)
if snapshot is not None:
print(datetime.now())
display_top(snapshot)
return
except Empty:
max_rss = getrusage(RUSAGE_SELF).ru_maxrss
if max_rss > old_max:
old_max = max_rss
snapshot = tracemalloc.take_snapshot()
print(datetime.now(), 'max RSS', max_rss)
def count_prefixes():
sleep(2) # Start up time.
counts = Counter()
fname = '/usr/share/dict/american-english'
with open(fname) as words:
words = list(words)
for word in words:
prefix = word[:3]
counts[prefix] += 1
sleep(0.0001)
most_common = counts.most_common(3)
sleep(3) # Shut down time.
return most_common
def main():
queue = Queue()
poll_interval = 0.1
monitor_thread = Thread(target=memory_monitor, args=(queue, poll_interval))
monitor_thread.start()
try:
most_common = count_prefixes()
print('Top prefixes:', most_common)
finally:
queue.put('stop')
monitor_thread.join()
def display_top(snapshot, key_type='lineno', limit=3):
snapshot = snapshot.filter_traces((
tracemalloc.Filter(False, "<frozen importlib._bootstrap>"),
tracemalloc.Filter(False, "<unknown>"),
))
top_stats = snapshot.statistics(key_type)
print("Top %s lines" % limit)
for index, stat in enumerate(top_stats[:limit], 1):
frame = stat.traceback[0]
# replace "/path/to/module/file.py" with "module/file.py"
filename = os.sep.join(frame.filename.split(os.sep)[-2:])
print("#%s: %s:%s: %.1f KiB"
% (index, filename, frame.lineno, stat.size / 1024))
line = linecache.getline(frame.filename, frame.lineno).strip()
if line:
print(' %s' % line)
other = top_stats[limit:]
if other:
size = sum(stat.size for stat in other)
print("%s other: %.1f KiB" % (len(other), size / 1024))
total = sum(stat.size for stat in top_stats)
print("Total allocated size: %.1f KiB" % (total / 1024))
main()
The resource
module lets you check the current memory usage, and save the snapshot from the peak memory usage. The queue lets the main thread tell the memory monitor thread when to print its report and shut down. When it runs, it shows the memory being used by the list()
call:
2018-05-29 10:34:34.441334 max RSS 10188
2018-05-29 10:34:36.475707 max RSS 23588
2018-05-29 10:34:36.616524 max RSS 38104
2018-05-29 10:34:36.772978 max RSS 45924
2018-05-29 10:34:36.929688 max RSS 46824
2018-05-29 10:34:37.087554 max RSS 46852
Top prefixes: [('con', 1220), ('dis', 1002), ('pro', 809)]
2018-05-29 10:34:56.281262
Top 3 lines
#1: scratches/scratch.py:36: 6527.0 KiB
words = list(words)
#2: scratches/scratch.py:38: 16.4 KiB
prefix = word[:3]
#3: scratches/scratch.py:39: 10.1 KiB
counts[prefix] += 1
19 other: 10.8 KiB
Total allocated size: 6564.3 KiB
If you're on Linux, you may find /proc/self/statm more useful than the resource
module.
A simple example to calculate the memory usage of a block of codes / function using memory_profile, while returning result of the function:
import memory_profiler as mp
def fun(n):
tmp = []
for i in range(n):
tmp.extend(list(range(i*i)))
return "XXXXX"
calculate memory usage before running the code then calculate max usage during the code:
start_mem = mp.memory_usage(max_usage=True)
res = mp.memory_usage(proc=(fun, [100]), max_usage=True, retval=True)
print('start mem', start_mem)
print('max mem', res[0][0])
print('used mem', res[0][0]-start_mem)
print('fun output', res[1])
calculate usage in sampling points while running function:
res = mp.memory_usage((fun, [100]), interval=.001, retval=True)
print('min mem', min(res[0]))
print('max mem', max(res[0]))
print('used mem', max(res[0])-min(res[0]))
print('fun output', res[1])
Credits: @skeept
This one has been answered already here: Python memory profiler
Basically you do something like that (cited from Guppy-PE):
>>> from guppy import hpy; h=hpy()
>>> h.heap()
Partition of a set of 48477 objects. Total size = 3265516 bytes.
Index Count % Size % Cumulative % Kind (class / dict of class)
0 25773 53 1612820 49 1612820 49 str
1 11699 24 483960 15 2096780 64 tuple
2 174 0 241584 7 2338364 72 dict of module
3 3478 7 222592 7 2560956 78 types.CodeType
4 3296 7 184576 6 2745532 84 function
5 401 1 175112 5 2920644 89 dict of class
6 108 0 81888 3 3002532 92 dict (no owner)
7 114 0 79632 2 3082164 94 dict of type
8 117 0 51336 2 3133500 96 type
9 667 1 24012 1 3157512 97 __builtin__.wrapper_descriptor
<76 more rows. Type e.g. '_.more' to view.>
>>> h.iso(1,[],{})
Partition of a set of 3 objects. Total size = 176 bytes.
Index Count % Size % Cumulative % Kind (class / dict of class)
0 1 33 136 77 136 77 dict (no owner)
1 1 33 28 16 164 93 list
2 1 33 12 7 176 100 int
>>> x=[]
>>> h.iso(x).sp
0: h.Root.i0_modules['__main__'].__dict__['x']
>>>
maybe it help:
<see additional>
pip install gprof2dot
sudo apt-get install graphviz
gprof2dot -f pstats profile_for_func1_001 | dot -Tpng -o profile.png
def profileit(name):
"""
@profileit("profile_for_func1_001")
"""
def inner(func):
def wrapper(*args, **kwargs):
prof = cProfile.Profile()
retval = prof.runcall(func, *args, **kwargs)
# Note use of name from outer scope
prof.dump_stats(name)
return retval
return wrapper
return inner
@profileit("profile_for_func1_001")
def func1(...)
Disclosure:
But nice because of its simplicity:
import resource
def using(point=""):
usage=resource.getrusage(resource.RUSAGE_SELF)
return '''%s: usertime=%s systime=%s mem=%s mb
'''%(point,usage[0],usage[1],
usage[2]/1024.0 )
Just insert using("Label")
where you want to see what's going on. For example
print(using("before"))
wrk = ["wasting mem"] * 1000000
print(using("after"))
>>> before: usertime=2.117053 systime=1.703466 mem=53.97265625 mb
>>> after: usertime=2.12023 systime=1.70708 mem=60.8828125 mb
Below is a simple function decorator which allows to track how much memory the process consumed before the function call, after the function call, and what is the difference:
import time
import os
import psutil
def elapsed_since(start):
return time.strftime("%H:%M:%S", time.gmtime(time.time() - start))
def get_process_memory():
process = psutil.Process(os.getpid())
mem_info = process.memory_info()
return mem_info.rss
def profile(func):
def wrapper(*args, **kwargs):
mem_before = get_process_memory()
start = time.time()
result = func(*args, **kwargs)
elapsed_time = elapsed_since(start)
mem_after = get_process_memory()
print("{}: memory before: {:,}, after: {:,}, consumed: {:,}; exec time: {}".format(
func.__name__,
mem_before, mem_after, mem_after - mem_before,
elapsed_time))
return result
return wrapper
Here is my blog which describes all the details. (archived link)