pickle: Faster serialization of Unicode strings #59801

vstinner · 2012-08-08T22:38:42Z

BPO	15596
Nosy	@jcea, @pitrou, @vstinner, @avassalotti, @serhiy-storchaka
Files	pickle_unicode.patch pickleutf8.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2013-04-07.15:50:10.726>
created_at = <Date 2012-08-08.22:38:41.790>
labels = ['library', 'performance']
title = 'pickle: Faster serialization of Unicode strings'
updated_at = <Date 2013-04-07.21:34:52.757>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2013-04-07.21:34:52.757>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2013-04-07.15:50:10.726>
closer = 'pitrou'
components = ['Library (Lib)']
creation = <Date 2012-08-08.22:38:41.790>
creator = 'vstinner'
dependencies = []
files = ['26730', '29690']
hgrepos = []
issue_num = 15596
keywords = ['patch']
message_count = 15.0
messages = ['167730', '167731', '167796', '167839', '167842', '167847', '167848', '178872', '178934', '186115', '186126', '186139', '186218', '186219', '186247']
nosy_count = 6.0
nosy_names = ['jcea', 'pitrou', 'vstinner', 'alexandre.vassalotti', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue15596'
versions = ['Python 3.4']

vstinner · 2012-08-08T22:38:39Z

Serialization of Unicode strings in the pickle module is suboptimal, especially for long strings.

Attached patch optimize the serialization thanks to new properties of Unicode strings (PEP-393):

text (protocol 0): avoid any temporary buffer if the string is an ASCII or latin1 string without "\\" or "\n" character; otherwise use a small buffer of 64 KB (instead of two buffer)
binary (protocol 1, 2): avoid any temporary buffer if string is an ASCII string or if the string is already available encoded as UTF-8

The current code for protocol 0 uses raw_unicode_escape() which is really suboptimal: it uses a first buffer to write the escape string, and then a new temporary buffer to store the buffer with the right size (instead of just calling _PyBytes_Resize).

vstinner · 2012-08-08T22:41:32Z

Oh, I forgot to explain that I initially wrote the patch to fix the following failure on our "bigmem" buildbot.

http://buildbot.python.org/all/builders/AMD64%20Ubuntu%20LTS%20bigmem%203.x/builds/165/steps/test/logs/stdio

======================================================================
ERROR: test_huge_str_32b (test.test_pickle.InMemoryPickleTests)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/opt/python-bigmem/3.x.langa-bigmem/build/Lib/test/support.py", line 1281, in wrapper
    return f(self, maxsize)
  File "/opt/python-bigmem/3.x.langa-bigmem/build/Lib/test/pickletester.py", line 1267, in test_huge_str_32b
    pickled = self.dumps(data, protocol=proto)
  File "/opt/python-bigmem/3.x.langa-bigmem/build/Lib/test/test_pickle.py", line 49, in dumps
    return pickle.dumps(arg, protocol)
MemoryError

pitrou · 2012-08-09T17:10:28Z

Looks interesting. Can you post benchmark numbers?
(you can use the pickle tests from http://hg.python.org/benchmarks )

vstinner · 2012-08-09T21:49:42Z

Here is a benchmark comparing Python 3.3 without and with my patch

ned$ python3 perf.py -b fastpickle,pickle_dict,pickle_list,slowpickle ../default/python ../fasterpickle/python
Running fastpickle...
INFO:root:Running ../fasterpickle/python performance/bm_pickle.py -n 50 --use_cpickle pickle
INFO:root:Running ../default/python performance/bm_pickle.py -n 50 --use_cpickle pickle
Running pickle_dict...
INFO:root:Running ../fasterpickle/python performance/bm_pickle.py -n 50 --use_cpickle pickle_dict
INFO:root:Running ../default/python performance/bm_pickle.py -n 50 --use_cpickle pickle_dict
Running pickle_list...
INFO:root:Running ../fasterpickle/python performance/bm_pickle.py -n 50 --use_cpickle pickle_list
INFO:root:Running ../default/python performance/bm_pickle.py -n 50 --use_cpickle pickle_list
Running slowpickle...
INFO:root:Running ../fasterpickle/python performance/bm_pickle.py -n 50 pickle
INFO:root:Running ../default/python performance/bm_pickle.py -n 50 pickle

Report on Linux ned 3.4.4-4.fc16.x86_64 #1 SMP Thu Jul 5 20:01:38 UTC 2012 x86_64 x86_64
Total CPU cores: 8

### fastpickle ###
Min: 0.530622 -> 0.332841: 1.59x faster
Avg: 0.539450 -> 0.336833: 1.60x faster
Significant (t=232.04)
Stddev: 0.00552 -> 0.00276: 2.0032x smaller
Timeline: b'http://tinyurl.com/dyu3vap'

The following not significant results are hidden, use -v to show them:
pickle_dict, pickle_list, slowpickle.

vstinner · 2012-08-09T22:03:37Z

For your information, results of benchmark comparing Python 3.2 to 3.3:

ned$ python3 perf.py -b fastpickle,pickle_dict,pickle_list,slowpickle ../3.2/python ../default/python
Running fastpickle...
INFO:root:Running ../default/python performance/bm_pickle.py -n 50 --use_cpickle pickle
INFO:root:Running ../3.2/python performance/bm_pickle.py -n 50 --use_cpickle pickle
Running pickle_dict...
INFO:root:Running ../default/python performance/bm_pickle.py -n 50 --use_cpickle pickle_dict
INFO:root:Running ../3.2/python performance/bm_pickle.py -n 50 --use_cpickle pickle_dict
Running pickle_list...
INFO:root:Running ../default/python performance/bm_pickle.py -n 50 --use_cpickle pickle_list
INFO:root:Running ../3.2/python performance/bm_pickle.py -n 50 --use_cpickle pickle_list
Running slowpickle...
INFO:root:Running ../default/python performance/bm_pickle.py -n 50 pickle
INFO:root:Running ../3.2/python performance/bm_pickle.py -n 50 pickle

Report on Linux ned 3.4.4-4.fc16.x86_64 #1 SMP Thu Jul 5 20:01:38 UTC 2012 x86_64 x86_64
Total CPU cores: 8

### fastpickle ###
Min: 0.455842 -> 0.542103: 1.19x slower
Avg: 0.462334 -> 0.547271: 1.18x slower
Significant (t=-101.15)
Stddev: 0.00362 -> 0.00471: 1.3028x larger
Timeline: b'http://tinyurl.com/btr644x'

### pickle_dict ###
Min: 0.360125 -> 0.345850: 1.04x faster
Avg: 0.364019 -> 0.348431: 1.04x faster
Significant (t=30.84)
Stddev: 0.00308 -> 0.00181: 1.6973x smaller
Timeline: b'http://tinyurl.com/cd3ashu'

### pickle_list ###
Min: 0.803941 -> 0.584800: 1.37x faster
Avg: 0.811115 -> 0.589200: 1.38x faster
Significant (t=455.00)
Stddev: 0.00261 -> 0.00225: 1.1612x smaller
Timeline: b'http://tinyurl.com/8u4m2wf'

### slowpickle ###
Min: 0.409008 -> 0.461257: 1.13x slower
Avg: 0.413668 -> 0.466201: 1.13x slower
Significant (t=-115.31)
Stddev: 0.00236 -> 0.00219: 1.0772x smaller
Timeline: b'http://tinyurl.com/czrg5kf'

avassalotti · 2012-08-09T22:08:24Z

Amazing! Though, it would probably be good idea to benchmarks non-ASCII strings as well.

vstinner · 2012-08-09T22:08:26Z

Last one: Python 3.2 vs patched Python 3.3.

ned$ python3 perf.py -b fastpickle,pickle_dict,pickle_list,slowpickle ../3.2/python ../fasterpickle/python
Running fastpickle...
INFO:root:Running ../fasterpickle/python performance/bm_pickle.py -n 50 --use_cpickle pickle
INFO:root:Running ../3.2/python performance/bm_pickle.py -n 50 --use_cpickle pickle
Running pickle_dict...
INFO:root:Running ../fasterpickle/python performance/bm_pickle.py -n 50 --use_cpickle pickle_dict
INFO:root:Running ../3.2/python performance/bm_pickle.py -n 50 --use_cpickle pickle_dict
Running pickle_list...
INFO:root:Running ../fasterpickle/python performance/bm_pickle.py -n 50 --use_cpickle pickle_list
INFO:root:Running ../3.2/python performance/bm_pickle.py -n 50 --use_cpickle pickle_list
Running slowpickle...
INFO:root:Running ../fasterpickle/python performance/bm_pickle.py -n 50 pickle
INFO:root:Running ../3.2/python performance/bm_pickle.py -n 50 pickle

Report on Linux ned 3.4.4-4.fc16.x86_64 #1 SMP Thu Jul 5 20:01:38 UTC 2012 x86_64 x86_64
Total CPU cores: 8

### fastpickle ###
Min: 0.470211 -> 0.322453: 1.46x faster
Avg: 0.475718 -> 0.328496: 1.45x faster
Significant (t=205.65)
Stddev: 0.00317 -> 0.00395: 1.2456x larger
Timeline: b'http://tinyurl.com/9qpphzp'

### pickle_dict ###
Min: 0.353965 -> 0.347959: 1.02x faster
Avg: 0.358980 -> 0.350596: 1.02x faster
Significant (t=10.44)
Stddev: 0.00545 -> 0.00160: 3.3956x smaller
Timeline: b'http://tinyurl.com/9pfeqf9'

### pickle_list ###
Min: 0.838222 -> 0.593497: 1.41x faster
Avg: 0.844636 -> 0.599491: 1.41x faster
Significant (t=296.53)
Stddev: 0.00520 -> 0.00267: 1.9521x smaller
Timeline: b'http://tinyurl.com/9rynvnv'

### slowpickle ###
Min: 0.408205 -> 0.458309: 1.12x slower
Avg: 0.413738 -> 0.463916: 1.12x slower
Significant (t=-53.85)
Stddev: 0.00263 -> 0.00604: 2.3019x larger
Timeline: b'http://tinyurl.com/coffkbg'

vstinner · 2013-01-03T01:14:15Z

serhiy: I'm not really motivated to finish the work on this issue (especially "... it would probably be good idea to benchmarks non-ASCII strings as well."). Would you like to work on this?

serhiy-storchaka · 2013-01-03T11:04:53Z

Well, I take care of this. I have the own patch for raw_unicode_escape() optimization, but microbenchmarks don't show any speed up. Maybe your approach will be better.

pitrou · 2013-04-05T23:27:46Z

Ping?

pitrou · 2013-04-06T14:39:27Z

Since protocol 0 is essentially dead in Python 3, I would like to propose something simpler and safer: only optimize the binary protocols. If noone beats me to it, I'll adapt Victor's patch for that.

pitrou · 2013-04-06T16:48:12Z

Here is a new patch. Benchmark:

### fastpickle ###
Min: 0.631457 -> 0.399104: 1.58x faster
Avg: 0.631868 -> 0.399519: 1.58x faster
Significant (t=701.85)
Stddev: 0.00037 -> 0.00064: 1.7604x larger
Timeline: http://tinyurl.com/c6n8h5g

python-dev · 2013-04-07T15:41:02Z

New changeset 09a84091ae96 by Antoine Pitrou in branch 'default':
Issue bpo-15596: Faster pickling of unicode strings.
http://hg.python.org/cpython/rev/09a84091ae96

pitrou · 2013-04-07T15:50:11Z

I've applied the review comments and committed the patch. Thank you!

vstinner · 2013-04-07T21:34:53Z

Hi Antoine, I prefer your patch. Great job!

2013/4/7 Antoine Pitrou <report@bugs.python.org>:

Antoine Pitrou added the comment:

I've applied the review comments and committed the patch. Thank you!

----------
resolution: -> fixed
stage: patch review -> committed/rejected
status: open -> closed

Python tracker <report@bugs.python.org>
<http://bugs.python.org/issue15596\>

vstinner added stdlib Python modules in the Lib dir performance Performance or resource usage labels Aug 8, 2012

pitrou closed this as completed Apr 7, 2013

ezio-melotti transferred this issue from another repository Apr 10, 2022

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pickle: Faster serialization of Unicode strings #59801

pickle: Faster serialization of Unicode strings #59801

vstinner commented Aug 8, 2012

vstinner commented Aug 8, 2012

vstinner commented Aug 8, 2012

pitrou commented Aug 9, 2012

vstinner commented Aug 9, 2012

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avassalotti commented Aug 9, 2012

vstinner commented Aug 9, 2012

vstinner commented Jan 3, 2013

serhiy-storchaka commented Jan 3, 2013

pitrou commented Apr 5, 2013

pitrou commented Apr 6, 2013

pitrou commented Apr 6, 2013

python-dev mannequin commented Apr 7, 2013

pitrou commented Apr 7, 2013

vstinner commented Apr 7, 2013

pickle: Faster serialization of Unicode strings #59801

pickle: Faster serialization of Unicode strings #59801

Comments

vstinner commented Aug 8, 2012

vstinner commented Aug 8, 2012

vstinner commented Aug 8, 2012

pitrou commented Aug 9, 2012

vstinner commented Aug 9, 2012

vstinner commented Aug 9, 2012

avassalotti commented Aug 9, 2012

vstinner commented Aug 9, 2012

vstinner commented Jan 3, 2013

serhiy-storchaka commented Jan 3, 2013

pitrou commented Apr 5, 2013

pitrou commented Apr 6, 2013

pitrou commented Apr 6, 2013

python-dev mannequin commented Apr 7, 2013

pitrou commented Apr 7, 2013

vstinner commented Apr 7, 2013