Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!rt.uk.eu.org!newsfeed.xs4all.nl!newsfeed4.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.030 X-Spam-Evidence: '*H*': 0.94; '*S*': 0.00; 'parameters': 0.04; '(even': 0.05; 'interpreter': 0.05; 'assigning': 0.09; 'naturally': 0.09; 'returns,': 0.09; 'variables.': 0.09; 'python': 0.11; 'thread': 0.14; 'assigns': 0.16; 'concurrency,': 0.16; 'concurrent': 0.16; 'fine-': 0.16; 'shot.': 0.16; 'subject:recursion': 0.16; 'tuning,': 0.16; 'appropriate': 0.16; 'wrote:': 0.18; 'bit': 0.19; 'work,': 0.20; 'to:name:python- list@python.org': 0.22; 'driver': 0.24; 'received:65.55.116': 0.24; 'subject:problem': 0.24; 'task': 0.26; 'pass': 0.26; 'certain': 0.27; 'header:In-Reply-To:1': 0.27; 'skip:- 40': 0.29; '[1]': 0.29; "i'm": 0.30; 'url:mailman': 0.30; 'code': 0.31; 'libraries': 0.31; 'run': 0.32; 'url:python': 0.33; 'date:': 0.34; 'subject:the': 0.34; 'problem': 0.35; 'but': 0.35; 'there': 0.35; 'accessing': 0.36; 'url:listinfo': 0.36; 'next': 0.36; 'method': 0.36; "i'll": 0.36; 'possible': 0.36; 'url:org': 0.36; 'should': 0.36; 'application': 0.37; 'email addr:python.org': 0.37; 'problems': 0.38; 'solving': 0.38; 'tasks': 0.38; 'url:library': 0.38; 'to:addr:python-list': 0.38; 'pm,': 0.38; 'little': 0.38; 'does': 0.39; 'subject:': 0.39; 'sure': 0.39; 'to:addr:python.org': 0.39; 'skip:p 20': 0.39; 'url:mail': 0.40; 'how': 0.40; 'even': 0.60; 'easy': 0.60; 'simple': 0.61; 'making': 0.63; 'email addr:gmail.com': 0.63; 're:': 0.63; 'more': 0.64; 'email name:python-list': 0.65; 'due': 0.66; '26,': 0.68; 'overcome': 0.74; 'bounded': 0.84; 'returns.': 0.84; 'careful': 0.91; 'simulation': 0.91; 'task,': 0.91; 'directly.': 0.95; '2013': 0.98 X-TMN: [rmYSv3HSjHLFrOOGyN1jqeUx63Gh9cR6] X-Originating-Email: [carlosnepomuceno@outlook.com] From: Carlos Nepomuceno To: "python-list@python.org" Subject: RE: Solving the problem of mutual recursion Date: Sun, 26 May 2013 21:09:29 +0300 Importance: Normal In-Reply-To: References: <55942e65-e4a5-45fc-b2fc-ceb4020959dd@k4g2000vba.googlegroups.com>, , Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginalArrivalTime: 26 May 2013 18:09:29.0445 (UTC) FILETIME=[2A4B7950:01CE5A3C] X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 49 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1369591777 news.xs4all.nl 15993 [2001:888:2000:d::a6]:36218 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:46091 ----------------------------------------=0A= > Date: Sun=2C 26 May 2013 10:21:05 -0700=0A= > Subject: Re: Solving the problem of mutual recursion=0A= > From: peter.h.m.brooks@gmail.com=0A= > To: python-list@python.org=0A= >=0A= > On May 26=2C 5:09 pm=2C Jussi Piitulainen =0A= > wrote:=0A= >>=0A= >> A light-weighter way is to have each task end by assigning the next=0A= >> task and returning=2C instead of calling the next task directly. When a= =0A= >> task returns=2C a driver loop will call the assigned task=2C which again= =0A= >> does a bounded amount of work=2C assigns the next task=2C and returns.= =0A= >> Tasks can even pass parameters in the same way.=0A= >>=0A= > Yes=2C that's true - there are a number of ways of making it linear.=0A= >=0A= > What I'm particularly pleased about with my method is the parallelism=0A= > that it achieves - with so little effort! The simulation is going to=0A= > be computationally intense and this is going to make sure that the=0A= > CPUs are all giving it their best shot. When I run this on my macbook=2C= =0A= > the python interpreter takes over 140% of CPU - with a bit of fine-=0A= > tuning=2C it should be possible to have more concurrent threads and to=0A= > use the four cores optimally.=0A= >=0A= > Naturally I'll need to be careful with the concurrency=2C but this is so= =0A= > simple and clean that it should be easy to avoid the main problems=0A= > with accessing the same variables.=0A= > --=0A= > http://mail.python.org/mailman/listinfo/python-list=0A= =0A= Python threads run in the same process and won't run concurrently:=0A= =0A= "CPython implementation detail: In CPython=2C due to the Global Interpreter= Lock=2C only one thread can execute Python code at once (even though certa= in performance-oriented libraries might overcome this limitation). If you w= ant your application to make better use of the computational resources of m= ulti-core machines=2C you are advised to use multiprocessing. However=2C th= reading is still an appropriate model if you want to run multiple I/O-bound= tasks simultaneously."[1]=0A= =0A= How can you get 140% of CPU? IS that a typo??=0A= =0A= [1] http://docs.python.org/2/library/threading.html =