April 2020 - Pharo-users - lists.pharo.org

mentor question 1

by Roelof Wobben

April 25, 2020

Re: [Pharo-users] mentor wanted

by Roelof Wobben

April 25, 2020

Re: [Pharo-users] mentor wanted

by Richard Sargent

On Fri, Apr 24, 2020, 22:25 Richard O'Keefe <raoknz(a)gmail.com> wrote: > Roelof, I don't think CRC cards or the GRASP patterns or anything like that > addresses your immediate needs. Based on other questions of yours it > seems to me that your problem is not *organising* the responsibilities in > an > OO program, but decomposing a problem into responsibilities in the first > place. I think this is perhaps the most important part of programming, and > the hardest to learn, not least because very few of us are good at teaching > it. We're not very good at teaching it in mathematics either. I do not > think > your issues are anything to do with Pharo, Smalltalk, OOP, or programming > as such. > > One symptom of the general problem that I've noticed is that I see code as > a very fluid sort of thing where pieces can be moved around and recombined, > while many people think of code as something solid and rather brittle. > > I was thinking of writing up a short description of what I was thinking > for a > RosettaCode example anyway. Would that help? > Thank you, Richard. I appreciate your offering this. I am not a teacher, so your help is truly appreciated! > > > On Thu, 23 Apr 2020 at 23:16, Roelof Wobben via Pharo-users > <pharo-users(a)lists.pharo.org> wrote: > > > > Hello, > > > > I like Pharo a lot but I hit a wall very often. > > With complex problems I do not see how to solve things in small steps. > > > > Is there somewhere who is willing to mentor me in how I can overcome > > that problem. > > > > Roelof > > > > > >

April 25, 2020

Re: [Pharo-users] mentor wanted

by Richard O'Keefe

Roelof, I don't think CRC cards or the GRASP patterns or anything like that addresses your immediate needs. Based on other questions of yours it seems to me that your problem is not *organising* the responsibilities in an OO program, but decomposing a problem into responsibilities in the first place. I think this is perhaps the most important part of programming, and the hardest to learn, not least because very few of us are good at teaching it. We're not very good at teaching it in mathematics either. I do not think your issues are anything to do with Pharo, Smalltalk, OOP, or programming as such. One symptom of the general problem that I've noticed is that I see code as a very fluid sort of thing where pieces can be moved around and recombined, while many people think of code as something solid and rather brittle. I was thinking of writing up a short description of what I was thinking for a RosettaCode example anyway. Would that help? On Thu, 23 Apr 2020 at 23:16, Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > Hello, > > I like Pharo a lot but I hit a wall very often. > With complex problems I do not see how to solve things in small steps. > > Is there somewhere who is willing to mentor me in how I can overcome > that problem. > > Roelof > >

April 25, 2020

Re: [Pharo-users] All file accesses get externalCalledFailed exceptions.

by Michael Burns

Thanks Tim! Problem solved. I did as you suggest and added Pharo.app (and Squeak*.app) to the "Files and Foldersâ and tried again. That resolved the primary issue but when opening File Browser I got a different exception referring to /.VolumeIcon.icns not being able to be opened. The volume was my boot partition and in Catalina that is a readonly filesystem. I looked at that file with ls and file commands, and it turns out that it was a broken link to the same file in the contained Data volume. The destination does not exist: [graphe:/Volumes/Graphe6] Michael% file .VolumeIcon.icns .VolumeIcon.icns: broken symbolic link to System/Volumes/Data/.VolumeIcon.icns So, I created an empty file there: [graphe:/Volumes/Graphe6] Michael% sudo touch .VolumeIcon.icns And rechecked the link: [graphe:/Volumes/Graphe6] Michael% file .VolumeIcon.icns .VolumeIcon.icns: empty File Browser now opens and lets me navigate around. All is well. > On Apr 22, 2020, at 5:40 AM, Tim Mackinnon <tim(a)testit.works> wrote: > > H Michael- that seems strange, I just tried the following on a Pharo8 with Catalina: > > OSPlatform current currentWorkingDirectoryPath. > > > /Users/macta/Dev/Smalltalk/Pharo/Pharo 8.0 - 64bit > > Iâm using PharoLauncher, although my images are not stored in Documents, but ~/Dev/Smalltalk/Pharo (I adjusted the launcher settings). Not sure if that makes a difference? Or - perhaps you didnât allow Pharo disk read privileges (that is a new security check in Catalina - see the OSX System Preferences, Security and Privacy, Files and Folders. Mine has a pharo entry with access to Downloads, Documents and Desktop). > > Tim > >> On 22 Apr 2020, at 10:25, Michael Burns via Pharo-users <pharo-users(a)lists.pharo.org <mailto:pharo-users@lists.pharo.org>> wrote: >> >> >> From: Michael Burns <michaelburns(a)mac.com <mailto:michaelburns@mac.com>> >> Subject: All file accesses get externalCalledFailed exceptions. >> Date: 22 April 2020 at 10:25:56 BST >> To: Pharo users <pharo-users(a)lists.pharo.org <mailto:pharo-users@lists.pharo.org>> >> >> >> Newbie to Pharo >> Just installed the latest 8.0 stable image. >> Some things work, but anything I do to access any files gets an exception dealing with getcwd in libc.dylib. >> >> I am running MacOS Catalina. >> I searched and found the lib.dylib file and it is an alias to another .dylib file. >> >> Is there something else I need to install or configure? >> >> <e876cb42-0161-4573-bdb7-0bf57c073efb.png> >> Sent from my iPad >> >

April 24, 2020

Re: [Pharo-users] Don't tell I sent that ;)

by Bernardo Ezequiel Contreras

see http://stephane.ducasse.free.fr/FreeBooks.html that's a good link. On Fri, Apr 24, 2020 at 4:57 AM CÃ©drick BÃ©ler <cdrick65(a)gmail.com> wrote: > Found the link. As I guess not legal, I send private. > > Iâve the book. I liked it if I remember ;) > > > https://doc.lagout.org/programmation/Smalltalk/Smalltalk%20-%20Objects%20an… > > Cheers, > CÃ©drick > -- Bernardo E.C. Sent from a cheap desktop computer in South America.

April 24, 2020

Re: [Pharo-users] Non-blocking IO

by Sven Van Caekenberghe

Daniel, > On 24 Apr 2020, at 12:35, Daniel TurczaÅski <mail(a)danielturczanski.com> wrote: > > Thanks. Are there any benchmarks available for Pharo HTTP servers? Is it > possible to achieve a performance similar to node.js? I know the biggest > selling point of Smalltalk is not perf but still I'm curious. Benchmarking is a black art with many pitfalls. Let's say that Pharo HTTP performance is acceptable. Here is a test that I just ran (on a LXC/LXD container on a big production server). t3@t3-pharo-test:~/tmp/pharo9$ cat /etc/lsb-release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=18.04 DISTRIB_CODENAME=bionic DISTRIB_DESCRIPTION="Ubuntu 18.04.4 LTS" t3@t3-pharo-test:~/tmp/pharo9$ curl get.pharo.org/64/90+vm | bash % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 3054 100 3054 0 0 198k 0 --:--:-- --:--:-- --:--:-- 198k Downloading the latest 90 Image: http://files.pharo.org/get-files/90/pharo64.zip Pharo.image Downloading the latest pharoVM: http://files.pharo.org/get-files/90/pharo64-linux-stable.zip pharo-vm/pharo Creating starter scripts pharo and pharo-ui t3@t3-pharo-test:~/tmp/pharo9$ ./pharo Pharo.image printVersion [version] 'Pharo9.0.0' 'Pharo-9.0.0+build.252.sha.fe2815c89f309789cbfba9a1ce821fb959dfe987 (64 Bit)' t3@t3-pharo-test:~/tmp/pharo9$ ./pharo Pharo.image eval --no-quit 'ZnServer startDefaultOn: 1701' & [1] 32203 a ZnManagingMultiThreadedServer(running 1701) t3@t3-pharo-test:~/tmp/pharo9$ curl http://localhost:1701/random 0BFE44ECF0BEEDDD949A8D5A363E5E6192A4B7CD4939E8BD7A7C7EC69995157 t3@t3-pharo-test:~/tmp/pharo9$ ab -k -n 1024 -c 8 http://localhost:1701/random This is ApacheBench, Version 2.3 <$Revision: 1807734 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking localhost (be patient) Completed 102 requests Completed 204 requests Completed 306 requests Completed 408 requests Completed 510 requests Completed 612 requests Completed 714 requests Completed 816 requests Completed 918 requests Completed 1020 requests Finished 1024 requests Server Software: Zinc Server Hostname: localhost Server Port: 1701 Document Path: /random Document Length: 64 bytes Concurrency Level: 8 Time taken for tests: 0.246 seconds Complete requests: 1024 Failed requests: 0 Keep-Alive requests: 1024 Total transferred: 256000 bytes HTML transferred: 65536 bytes Requests per second: 4155.22 [#/sec] (mean) Time per request: 1.925 [ms] (mean) Time per request: 0.241 [ms] (mean, across all concurrent requests) Transfer rate: 1014.46 [Kbytes/sec] received This is a small, do nothing request, tested locally, and so on. I would say it is safe to say you can handle 100s to 1000s of requests per second on a single Pharo instance (which is using only a single core). The good thing about HTTP is that you can normally scale horizontally by adding more and more worker instances under a load balancer -- these are standard techniques. HTH, Sven > The Concurrency book [1] says that Pharo's Process is like a fibre and is > lightweight. How big is the stack? Java Quasar's fibers are very lightweight > with a 400 byte stacks [2]. Can you have hundreds or thousands of processes > running blocking IO without much memory and performance penalty? > > [1] http://books.pharo.org/booklet-ConcurrentProgramming/ > [2] > https://docs.paralleluniverse.co/quasar/javadoc/co/paralleluniverse/fibers/… > > > > -- > Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html >

April 24, 2020

Re: [Pharo-users] Non-blocking IO

by Daniel TurczaÅski

Thanks. Are there any benchmarks available for Pharo HTTP servers? Is it possible to achieve a performance similar to node.js? I know the biggest selling point of Smalltalk is not perf but still I'm curious. The Concurrency book [1] says that Pharo's Process is like a fibre and is lightweight. How big is the stack? Java Quasar's fibers are very lightweight with a 400 byte stacks [2]. Can you have hundreds or thousands of processes running blocking IO without much memory and performance penalty? [1] http://books.pharo.org/booklet-ConcurrentProgramming/ [2] https://docs.paralleluniverse.co/quasar/javadoc/co/paralleluniverse/fibers/… -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

April 24, 2020

Re: [Pharo-users] Non-blocking IO

by dturczanski

Thanks for pointing out the difference between non-blocking and async IO. I think in Java NIO there is a thread that constantly calls the [e]poll() in the background and this way the IO becomes non-blocking. -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

April 24, 2020

Re: [Pharo-users] mentor wanted

by Roelof Wobben

Op 24-4-2020 om 09:49 schreef Hilaire: > Find it. > > It is a chapter of the book Squeak, Open Personal Computing and > Multimedia <http://sdmeta.gforge.inria.fr/FreeBooks/CollectiveNBlueBook/> > > http://sdmeta.gforge.inria.fr/FreeBooks/GuzdialBookDrafts/DesignObjects-ch4… > > > Le 24/04/2020 Ã 09:39, Hilaire a Ã©critÂ : >> I remember about a Smalltalk book presenting the CRC concept >> precisely used to cut complex problem in small chunks. > Hilaire and Cedric thanks, I will also study those.

April 24, 2020