Mailman 3 March 2015 - Python-Dev

Asking for review for Windows issues 21518 and 22080
by Claudiu Popa March 7, 2015

March 7, 2015

Hello, The winreg module has a function for loading a registry key under another registry key, called winreg.LoadKey. Unfortunately, the module doesn't provide a way to unload that key after the user finishes operating with it. There's a patch [1] for exporting the RegUnloadKey [2] API in winreg module as winreg.UnloadKey, similar to how RegLoadKey is exported as winreg.LoadKey. The patch is helped by another one [3], which provides a new module, test.support.windows_helper, for handling … [View More]

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Optimize binary insertion sort algorithm in Timsort.
by nha pham March 7, 2015

March 7, 2015

This describes an optimization for "binary insertion sort" (BINSORT for short). BINSORT has been implemented in Python, CyThon, and Timsort (the default Array.sort() in JAVA SE 7 and JAVA SE 8) I have read the BINSORT in Timsort http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8-b1… and I think that I can make a little more optimization. ================= The old BINSORT: The basic idea is to use binary search on the sorted list to find a final position for a new … [View More]element X, then insert X to the sorted list. [SORTED_LIST], [X in UNSORTED_LIST] // pick X in UNSORTED_LIST index = binarySeach([SORTED_LIST]) // use binary search to find appropriate location for X in SORTED_LIST [SORTED_LIST].add(index, X) // insert X to index location ================== New BINSORT: [SORTED_LIST], [A] // A is an UNSORTED_LIST j = compare(A[i], A[i+1]) // pick A[i], compare to next element index = binarySeach([SORTED_LIST], A[i]) // use binary search to find // appropriate location for A[i] in SORTED_LIST, and remember the index [SORTED_LIST].add(index, A[i]) // insert A[i] to index location // Now for A[+1], where already know where it should be, compare to A[i] if j >= 0: // A[i] > A[i+1], so A[i+1] will be in the right side of A[i] // We only have to search on a reduced Array: index = binarySearch(SORTED_LIST[index : length(SORTED_LIST)], A[i+1]) else: // we search on the left side of of A[i] index = binarySearch(SORTED_LIST[0 : index], A[i+1]) [SORTED_LIST].add(index, A[i+1]) // insert A[i+1] to index location //repeat the loop ================== Run test. Intuitively, new BINSORT will be better if the Array become bigger, because it reduce the array to search with the cost of only 1 more comparison. I only care about small array, with the length < 100 (we have known that in Timsort, the list is divided to chunks with length 64, then apply BINSORT to them). So I make a big Array, divide them, and apply new BINSORT in each chunk, then compare to OLD BINSORT. The source code is in the bottom of this document. Here is the results: cpuinfo: model name : Intel(R) Core(TM) i3 CPU M 350 @ 2.27GHz stepping : 2 microcode : 0xc cpu MHz : 933.000 cache size : 3072 KB ----- random array: ARRAY_SIZE: 1000000 CHUNK_SIZE: 100 DATA: randint(0, 1000000) OLD BINSORT: 81.45754 new BINSORT: 5.26754 RATIO: (OLD - new) / new = 14.464 --- incremental array: ARRAY_SIZE: 1000000 CHUNK_SIZE: 100 DATA: range(0, 1000000) OLD BINSORT: 81.87927 new BINSORT: 5.41651 RATIO: (OLD - new) / new = 14.11659 --- decremental array: ARRAY_SIZE: 1000000 CHUNK_SIZE: 100 DATA: range(0, 1000000) OLD BINSORT: 81.45723 new BINSORT: 5.09823 RATIO: (OLD - new) / new = 14.97753 ---- all equal array: ARRAY_SIZE: 1000000 CHUNK_SIZE: 100 DATA: 50000 OLD BINSORT: 40.46027 new BINSORT: 5.41221 RATIO: (OLD - new) / new = 6.47573 ==================== What should we do next: - Tuning my test code (I have just graphed it). - Test other cases, and bigger array (my laptop cannot handle array more than 10^6.) - Modifying Timsort in java.util. and test if it is better. ==================== My test code, written by Python. from timeit import Timer setup ="""\ import bisect from random import randint from timeit import Timer SIZE = 1000000 CHUNK = 100 NUM_CHUNK = SIZE/CHUNK data = [] data2 = [] data3 = [] for i in range(0,SIZE): data.append(randint(0,1000000)) #data.append(i) #data = data[::-1] """ sample ="""\ for j in range(0,NUM_CHUNK): low = CHUNK*j high= low + CHUNK data2.append(data[low]) index = low for i in range(low,high): x = data[i] index = bisect.bisect_right(data2[low:], x, low, len(data2) - low-1) data2.insert(index, x) """ new ="""\ for j in range(0,NUM_CHUNK): low = CHUNK*j high= low + CHUNK data3.append(data[low]) index = low for i in range(low,high): x = data[i] if x >= data[i-1]: index = bisect.bisect_right(data3[low:len(data3) - low-1], x, index, len(data3) - low-1) else: index = bisect.bisect_right(data3[low:index], x, low, index) data3.insert(index, x) """ t2 = Timer(stmt = sample, setup=setup) a = t2.timeit(1) print a t3 = Timer(stmt = new, setup=setup) b = t3.timeit(1) print b print (str((a - b)/b)) ==================================== Nha Pham Mar 07 2015 [View Less]

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Summary of Python tracker Issues
by Python tracker March 6, 2015

March 6, 2015

ACTIVITY SUMMARY (2015-02-27 - 2015-03-06) Python tracker at http://bugs.python.org/ To view or respond to any of the issues listed below, click on the issue. Do NOT respond to this message. Issues counts and deltas: open 4804 (+16) closed 30555 (+45) total 35359 (+61) Open issues with patches: 2260 Issues opened (47) ================== #22079: Ensure in PyType_Ready() that base class of static type is sta http://bugs.python.org/issue22079 reopened by doko #23538: New Windows … [View More]

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subprocess, buffered files, pipes and broken pipe errors
by Victor Stinner March 6, 2015

March 6, 2015

Hi, => I propose to ignore BrokenPipeError on Popen.__exit__(), what do you think? A recent issue fixed subprocess.Popen.__exit__() to read the exit status of the child process, even if stdin.close() raised a BrokenPipeError: http://bugs.python.org/issue21619 When I saw the issue, I was surprised that Popen.__exit__() doesn't ignore BrokenPipeError. Popen.communicate() is designed to handle corner cases and it ignores BrokenPipeError. Popen.__exit__() only returns when the process … [View More]

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PEP 485 review (isclose())
by Guido van Rossum March 5, 2015

March 5, 2015

I think it's time to accept PEP 485. I've re-read it once more, and it looks like the text is in great shape. (My only recommendation would be to update the Abstract to state that we're specifically adding math.isclose().) A wording question: "This implementation has a flag that lets the user select which relative tolerance test to apply -- this PEP does not suggest that that be retained, but rather than the weak test be selected." -- I think this was meant to say "... rather *that* the weak … [View More]

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Make review
by Serhiy Storchaka March 5, 2015

March 5, 2015

If you have ready patches that wait for review and committing, tell me. Send me no more than 5 links to issues per person (for first time) in private and I'll try to make reviews if I'm acquainted with affected modules or areas.

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Re: [Python-Dev] Python-Dev Digest, Vol 140, Issue 6
by SHAHRUKH KHAN March 5, 2015

March 5, 2015

i think it's time to rename math module to math.py module On Thu, Mar 5, 2015 at 4:30 PM, <python-dev-request(a)python.org> wrote: > Send Python-Dev mailing list submissions to > python-dev(a)python.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://mail.python.org/mailman/listinfo/python-dev > or, via email, send a message with subject or body 'help' to > python-dev-request(a)python.org > > You can reach the … [View More]

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Any volunteers to implement PEP 479?
by Guido van Rossum March 5, 2015

March 5, 2015

There's a proof of concept patch in http://bugs.python.org/issue22906, but it doesn't have the __future__ import and probably gets other details wrong. Reference: PEP 479 -- Change StopIteration handling inside generators <https://www.python.org/dev/peps/pep-0479/> -- --Guido van Rossum (python.org/~guido)

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Wg: Re: [Python-checkins] cpython (3.4): Issue #23446: Use PyMem_New instead of PyMem_Malloc to avoid possible integer
by s.krah March 1, 2015

March 1, 2015

== == == == == == Weitergeleitete Nachricht == == == == == == Absender : Stefan Krah<stefan(a)bytereef.org> Empfänger : "Victor Stinner"<victor.stinner(a)gmail.com> Datum : So, 01 Mrz 2015 18:58:43 +0000 Betreff : Re: [Python-Dev] [Python-checkins] cpython (3.4): Issue #23446: Use PyMem_New instead of PyMem_Malloc to avoid possible integer == == == == == == Weitergeleitete Nachricht == == == == == == On Mon, Feb 16, 2015 at 10:14:59PM +0100, Victor Stinner wrote: … [View More]

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