[issue38477] magiccube2x2 permutations 28% slower with Python 3.8.0rc1 vs 3.7
New submission from Louis Huemiller : Have created a program that by brute force determines all reachable states of a 2-by-2 MagicCube, sometimes referred to as a 2x2 Rubick's cube. On one of my servers, which is described in the attached file 20191011b_configuration, this program takes 19520.03 seconds to execute under Python2.7.15+, while under 3.8.0rc1 it takes 21887.53 seconds. This program is taking 12.13% longer to execute with 3.8.0rc1 versus 2.7.15+. The exact versions of Python as reported by sys.version are: 2.7.15+ (default, Oct 7 2019, 17:39:04) [GCC 7.4.0] 3.8.0rc1 (default, Oct 1 2019, 21:48:24) [GCC 7.4.0] Used the following script to execute this program under Python 2.7, 3.6, 3.7, and 3.8: mkdir -p ./results echo " git log " > ./results/20191011b_configuration git log -n4 >> ./results/20191011b_configuration echo "" >> ./results/20191011b_configuration echo " uname " >> ./results/20191011b_configuration uname -a >> ./results/20191011b_configuration echo "" >> ./results/20191011b_configuration echo " lsb_release " >> ./results/20191011b_configuration lsb_release -a >> ./results/20191011b_configuration echo "" >> ./results/20191011b_configuration echo " lshw " >> ./results/20191011b_configuration sudo lshw >> ./results/20191011b_configuration make clean make ./target/permutations2x2 > \ ./results/20191011b_magiccube2x2_permutations_cxx_unordered_map 2>&1 python3.8 ./permutations2x2 > \ ./results/20191011b_magiccube2x2_permutations_python3.8.0rc1 2>&1 python3.7 ./permutations2x2 > \ ./results/20191011b_magiccube2x2_permutations_python3.7 2>&1 python3.6 ./permutations2x2 > \ ./results/20191011b_magiccube2x2_permutations_python3.6 2>&1 python2.7 ./permutations2x2 > ./results/20191011b_magiccube2x2_permutations_python2.7 2>&1 Doing egrep "^# Total_Time:" on each of the output files, shows that the various executions took the following amount of time: cxx_unordered_map:# Total_Time: 1098.25 python2.7:# Total_Time: 19520.03 python3.6:# Total_Time: 19562.28 python3.7:# Total_Time: 17012.67 python3.8.0rc1:# Total_Time: 21887.53 Under Python2.7 and Python3.6 the program ran in approximately the same amount of time, while under Python3.7 it ran 12.8% faster than execution with Python2.7. Finally, the python3.8.0rc1 execution is noticeably slower than all the other executions, at 12.1% lower than Python2.7 and 28.6% slower than Python3.7. The source for the magic_cube2x2 program is available under gist.github.com at: https://gist.github.com/lhuemill/f1273291e5f5e85e4b42e5c7614e60ef This program creates a fairly large dictionary of 88.179840M entries. Each entry has a key of a string of length 29 and a value string of with a maximum length of 22 characters. A quick back-of-the-envelope calculation shows that this dictionary would use approximately 9GB of memory, but for some reason, all of the Python executions use approximately 22.6GB of memory. Even the C++ version is using 20.2GB when the permutations are stored in an unordered_map and 20.55GB when stored in a map. Quite surprising that the C++ is using over twice the expected amount of memory. CAUTION: When executing this program with less than the needed amount of physical memory, be careful that swap is not backed by a flash device. Doing so will likely cause a significant amount of I/O to the flash device and likely quickly wear it out. -- files: 20191005b_configuration messages: 354682 nosy: Louis Huemiller priority: normal severity: normal status: open title: magiccube2x2 permutations 28% slower with Python 3.8.0rc1 vs 3.7 type: performance versions: Python 3.8 Added file: https://bugs.python.org/file48660/20191005b_configuration ___ Python tracker <https://bugs.python.org/issue38477> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue38477] magiccube2x2 permutations 28% slower with Python 3.8.0rc1 vs 3.7
Louis Huemiller added the comment: Attached is a chart, which shows the results from the runs mentioned in the initial post. This chart was produced through the use of: ../permutations2x2_chart_results \ -f ./20191011b_chart.svg \ C++unordered_map:./20191011b_magiccube2x2_permutations_cxx_unordered_map \ Python2.7:./20191011b_magiccube2x2_permutations_python2.7 \ Python3.6:./20191011b_magiccube2x2_permutations_python3.6 \ Python3.7:./20191011b_magiccube2x2_permutations_python3.7 \ Python3.8.0rc1:./20191011b_magiccube2x2_permutations_python3.8.0rc1 The permutations2x2_chart_results program is present in the gist.github repository mentioned in the initial post. -- Added file: https://bugs.python.org/file48664/20191011b_chart.svg ___ Python tracker <https://bugs.python.org/issue38477> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue38477] magiccube2x2 permutations 28% slower with Python 3.8.0rc1 vs 3.7
Louis Huemiller added the comment: Each of the Python runs mentioned in the initial post took around 4 hours to execute. Although not as accurate, the issue can be demonstrated in less than 5 minutes through the use of: # If needed use the following to install Python3.8.0rc1 $ apt-get update $ sudo apt-get upgrade $ sudo add-apt-repository ppa:deadsnakes/ppa $ sudo apt update $ sudo apt install python3.8 # Use Python3.7 to produce baseline. $ python3.7 permutations2x2 --max_depth 6 | egrep "^# Total_Time" # Perform Python3.8.0rc1 execution python3.8 permutations2x2 --max_depth 6 | egrep "^# Total_Time" When I did this on my server the Python3.7 execution produced: # Total_Time: 62.46 While the Python3.8.0rc1 execution produced: # Total_Time: 79.72 By running the program with "--max_depth 6" specified, the program only traversed through permutations that are up to 6 moves from the initial position. Although much less than running through an unlimited number of moves, the above run still showed the Python3.8.0rc1 run as 26.7% ((79.72 - 62.46) / 62.46) slower than the Python3.7 execution. Which is close to the 28.6% reduction in performance seen from runs with unlimited depth of moves. -- ___ Python tracker <https://bugs.python.org/issue38477> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue38477] magiccube2x2 permutations 28% slower with Python 3.8.0rc1 vs 3.7
Louis Huemiller added the comment: Thank you for looking into the potential issue. Instead of getting Python3.8 from ppa:deadsnakes/ppa, I downloaded the source from: https://www.python.org/ftp/python/3.8.0/Python-3.8.0rc1.tgz Then did the following to build and install it: $ cd /usr/src $ sudo tar xzf ~/Python-3.8.0rc1.tgz $ cd Python-3.8.0rc1/ $ sudo ./configure --enable-optimizations $ sudo apt-get install zlib1g-dev $ sudo -H make altinstall Then re-running the magiccube2x2 permutations with a max_depth of 6 I obtained: $ python3.7 permutations2x2 --max_depth 6 | egrep "^# Total_Time" # Total_Time: 61.90 $ python3.8 permutations2x2 --max_depth 6 | egrep "^# Total_Time" # Total_Time: 82.45 Unfortunately, this still shows the Python3.8 execution as significantly slower, in this case 33.2% slower. Not sure of the cause, but perhaps I wasn't completely successful at removing the prior installation from ppa:deadsnakes/ppa. I removed it through the use of: $ sudo apt remove python3.8 $ sudo add-apt-repository -r ppa:deadsnakes/ppa $ shutdown -r now Next step I will completly re-install this server and then only install Python3.8 from https://www.python.org/ftp/python/3.8.0/Python-3.8.0rc1.tgz. -- ___ Python tracker <https://bugs.python.org/issue38477> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue38477] magiccube2x2 permutations 28% slower with Python 3.8.0rc1 vs 3.7
Louis Huemiller added the comment: Reinstalled the server I'd been using for this issue, with Ubuntu 18.04.3 LTS Server amd64. This installation already came with Python3.6.8. Downloaded and installed Python3.7.3 and 3.8.0 from: https://www.python.org/ftp/python/3.7.3/Python-3.7.3.tgz https://www.python.org/ftp/python/3.8.0/Python-3.8.0.tgz The installation process was somewhat complicated, with several to be discovered prerequisites. Used "apt install" to install the following needed dependencies: build-essential checkinstall libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev zlib1g-dev libffi-dev Then was able to do the following to build and install the downloaded Python3.7.3 and 3.8.0: $ sudo ./configure --enable-optimizations $ sudo -H make altinstall Then downloaded a clone of my magiccube2x2 repository and obtained the following results: $ python3.6 ./permutations2x2 --max_depth 6 | egrep "^# Total_Time:" # Total_Time: 69.02 $ python3.7 ./permutations2x2 --max_depth 6 | egrep "^# Total_Time:" # Total_Time: 84.52 $ python3.8 ./permutations2x2 --max_depth 6 | egrep "^# Total_Time:" # Total_Time: 83.14 In this case the runtimes under both of the Python versions that I downloaded the source for and built are significantly slower than the run with python3.6, which came already as part of Ubuntu 18.04.3. Instead of using the version of python3.7.3 that I built, was able to do: $ sudo apt install python3.7 to get one that had already been built for Ubuntu. Doing this allowed the following result: $ /usr/bin/python3.7 ./permutations2x2 --max_depth 6 \ | egrep "^# Total_Time:" # Total_Time: 62.39 Which is better than even the Python3.6 result. Unfortunately, there is not currently a pre-built Ubuntu package for Python3.8 and the one from ppa:deadsnakes/ppa, I already know has the performance issue. I did some searching on wiki.python.org and I was unable to find any instructions for how to build python from the source. Perhaps the instructions are already there but I was unable to find them. Perhaps this issue should be re-opened as a documentation error. I could really use instructions on how to built a performance version of Python and I suspect several others could also use this. For example, I'd like to pass that information to the maintainers of the deadsnakes repository. -- ___ Python tracker <https://bugs.python.org/issue38477> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
