- Pharo-dev - lists.pharo.org

Dealing with Class and Metaclass instances when using STON
by Sven Van Caekenberghe Dec. 26, 2015

Dec. 26, 2015

Hi, In STON #bleedingEdge I added the ability to write and read Class and Metaclass instances by using their global name. So, Point will be written as Class[#Point] while Point class will be written as Metaclass[#Point]. This is of course a short-circuit solution for the complex structure that a class actually is, but a reasonable compromise. It is in any case better than not handling these types of instances, which was the case before. === Name: STON-Core-SvenVanCaekenberghe.64 Author: SvenVanCaekenberghe Time: 23 December 2015, 10:50:14.195912 pm UUID: b7ced20a-a7a4-4b0f-8f27-db73231eeecb Ancestors: STON-Core-SvenVanCaekenberghe.63 Added the ability to write and read Class and Metaclass instances using their global name === Name: STON-Tests-SvenVanCaekenberghe.59 Author: SvenVanCaekenberghe Time: 23 December 2015, 10:51:06.830762 pm UUID: 9f684bc1-45e1-4bfa-885b-c56ea178bfca Ancestors: STON-Tests-SvenVanCaekenberghe.58 Added unit test for the ability to write and read Class and Metaclass instances using their global name === Thanks to Norbert Hartl for requesting the feature and for test driving it. Sven

3 5

Are Critical Tools Becoming Too Brittle?
by Sean P. DeNigris Dec. 25, 2015

Dec. 25, 2015

I just tried to inspect a domain object and I froze my image and had to force quit. How do I debug this? And, more importantly, when an error is encountered in a critical, basic tool like this, should there be some reasonable bare-bones alternative, like the emergency debugger? Not being able to inspect an object without crashing seems like a pretty crippling situation... ----- Cheers, Sean -- View this message in context: http://forum.world.st/Are-Critical-Tools-Becoming-Too-Brittle-tp4867206.html Sent from the Pharo Smalltalk Developers mailing list archive at Nabble.com.

7 13

AgileVisualization - call for reviewers
by Alexandre Bergel Dec. 24, 2015

Dec. 24, 2015

Dear All, As you may have heard, AgileVisualization is a book about the Roassal visualization engine. We hope to have the book released soon, within a couple of months. It would be fantastic to have feedback: http://agilevisualization.com The book is a fantastic result of the community. You guys made this possible, and we wish to thank you very much for this. Beers will flow at ESUG for everybody who comment on the chapters :-) We also have live discussion on Slack, channel #Roassal (see http://pharo.org/community on how to join Slack) Cheers, Alexandre -- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.bergel.eu ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.

2 1

Object graph stream/visitor implementation?
by Denis Kudriashov Dec. 24, 2015

Dec. 24, 2015

Hello. Do we have way to traverse object graph? I want stream which iterate object graph through instance variables with knowledge about path at every step. Maybe Fuel has classes for this ? Best regards, Denis

5 6

Examples
by Alexandre Bergel Dec. 24, 2015

Dec. 24, 2015

Hi! Having examples on the class sides imply that examples are not apparent when I do not select the class side of a class. And this is a pityâ¦ Maybe a particular icon can designate classes with examples? Or what about making the <script> pragma works also for instance methods and not only class methods? Cheers, Alexandre -- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.bergel.eu ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.

2 2

Classes with isVariable=true
by Denis Kudriashov Dec. 24, 2015

Dec. 24, 2015

Hello. I try to look how many classes has "isVariable=true" and "instSize>0". And I found two strange cases: PathTests and FileReferenceTest is variable classes. Why they are variable? And more general: how classes become variable? For example Path isVariable = true. But I not see initialize method which set it. Best regards, Denis

3 3

Re: [Pharo-dev] Examples
by Torsten Bergmann Dec. 23, 2015

Dec. 23, 2015

1 0

Can I access symbolic constants from NB FFI?
by Mariano Martinez Peck Dec. 23, 2015

Dec. 23, 2015

Hi guys, Say I want to call to waitpid like this: waitpid(childID, &status, WNOHANG); How can I do since I don't have access to WNOHANG int value in order to send it via argument .... ??? Any idea? Thanks in advance, -- Mariano http://marianopeck.wordpress.com

6 8

Re: [Pharo-dev] [Pharo-users] [ANN] Pharo Consortium Sponsored Development Effort
by Ben Coman Dec. 23, 2015

Dec. 23, 2015

On Tue, Dec 22, 2015 at 3:20 AM, Mariano Martinez Peck <marianopeck(a)gmail.com> wrote: > > > On Sun, Dec 20, 2015 at 5:21 PM, Thierry Goubier <thierry.goubier(a)gmail.com> > wrote: >> >> Hi Mariano, >> >> Le 20/12/2015 19:54, Mariano Martinez Peck a Ã©crit : >>> >>> Hi Dimitri, Dave et all. >>> >>> First let me do a little disclaimer. Regarding the developments itself >>> of this sponsorship, we discussed about the topics I said in the first >>> email. However, those are not written in stone and that's why I also >>> asked for feedback. As you know, Pharo has relatively little resources >>> so those should be well spent. If we decide to take a spin into a >>> project X, it doesn't mean other projects are not worth. It simply means >>> that we think X will be the most useful for the time being. >>> >>> One of the final goals of the discusses topics, is to improve a bit the >>> infrastructure for using Pharo as scripting (imagine Coral). For such a >>> thing, we believe that improving FileSystem and OSProcess-like is a good >>> first step to improve the underlying infrastructure. >> >> >> Would we have access then to a command-line oriented minimal Pharo image? >> > > Well, just for putting perspective my sponsorship is about 3 full months of > work effort. It doesn't mean I won't work beyond that. But to give you an > idea. I think we all want minimal images , command line etc. And Pharo has > already done a huge effort in that direction. >>> >>> That being said, I of course like the idea of distributing processing >>> across multiple images. No wonder, my PhD tool (Marea) and related >>> sub-projects (Fuel, Ghost proxies, etc) have something to do with the >>> mentioned topic. Dave already mentioned about RemoteTask, which was >>> something I was about to mention. There is also Seamless project (now >>> used by Remote Debugger stuff) and quite other tools. Finally, I think >>> this project may have a big percentage that could be considered as >>> "research". So having a PhD / master student working on this would also >>> be nice. In fact, maybe Denis Kudriashov might work on that topic??? (he >>> is now in RMOD team). >>> >>> Also, not that forking the image is not my main short-term goal. As >>> said, I will experiment first with a simple tool to execute OS commands >>> that would be FFI based, trying to make async operations, and that would >>> help in most cases. Maybe for those that are not supported, then >>> fallback in OSProcess. Note that Dave (OSProcess author) is very helpful >>> with me and we are discussing together about this. >> >> >> My guess is that, at least on Linux/Unix, that FFI will be exactly the >> same as the one used/expressed by the OSProcess plugin, that is >> popen/system. > > > No, wait. You are getting down to the details so I want to discuss :) > > OSProcess does not use popen()/system() but rather fork()+exec(). That means > that OSProcess has implementing the very very low building blocks that would > allow you do to almost everything. But then it has it's complicated matters. > fork() + exec() cannot be implemented via FFI (this was already discussed in > another thread). Can you link that thread? I'm curious to learn this. Is it multi-thread related? I read [a]... ..."The biggest problem with using fork+exec in this way is that you can't guarantee *nothing* happens between the fork call and the exec call. If, for example, the JVM decides to GC or move memory around, you can have a fatal crash at the JVM process level. Because of that, I don't recommend using fork + exec via FFI in JRuby, even though it's pretty cool. " ..."However, since this post I've learned of the "posix_spawn" [b] function available on most Unix variants. It's basically fork + exec in a single function, plus most of the typical security and IO tweaks you might do after forking and before execing. It's definitely my recommended alternative to fork+exec for JRuby." And posix_spawn also seems recommended for use with the JVM [d] and that Windows and POSIX might have similar usage, and even better match Windows CreateProcess than fork/exec [f] [g] [h] And since with 64-bit Spur we can expect very large images, spawn may be preferred over fork/exec to minimize memory usage for creating application subprocesses [i] Fork versus threads section of [c] or should we be making use of pthread_atfork [e] ? Overall I learnt something new about forking in a multi-threaded environment "When fork() is called, only the calling thread is duplicated in the child process." [a] http://blog.headius.com/2009/05/fork-and-exec-on-jvm-jruby-to-rescue.html [b] http://pubs.opengroup.org/onlinepubs/009695399/functions/posix_spawn.html [d] http://skife.org/java/2012/01/24/java_daemonization_with_gressil.html [c] http://repository.readscheme.org/ftp/papers/sw2002/gasbichler.pdf [e] http://stackoverflow.com/questions/4223553/c-does-exec-have-to-immediately-… [f] http://stackoverflow.com/questions/33249253/what-is-the-difference-between-… [g] http://stackoverflow.com/questions/5883462/linux-createprocess [h] http://www.linuxquestions.org/questions/programming-9/fork-exec-versus-posi… [i] http://www.oracle.com/technetwork/server-storage/solaris10/subprocess-13643… > However, there is a lot of other stuff that we believe it > could. So... what we wanted to see if it is possible is to have one only (or > very few) primitives (like forkAndExec) and all the rest via FFI. And then > all the features I listed in the first email of this thread. > > With that in mind, we believe that: > > 1) Before starting dealing with forkAndExec, we could try a first prototype > using popen(). That would allow us test a 100% FFI based approeach, deal > with writing and reading from pipes via stream, face the blocking issue, see > a prototype on how to read async from pipes etc etc etc. If we see this > works nicely, on a second step we can build another approach that instead of > popen() uses forkAndExec primitive. Is popen() being restricted to unidirectional part of this consideration [j] ? Also I read [j] that a problem with popen is that you do not get pid of child so you cannot wait on command to complete. Could posix_spawn be preferrable to popen? and just btw, mildly interesting is using sockets rather than pipes for interprocess communication [l] [j] http://stackoverflow.com/questions/3884103/can-popen-make-bidirectional-pip… [k] http://stackoverflow.com/questions/6743771/popen-alternative [l] http://stackoverflow.com/questions/25161377/open-a-cmd-program-with-full-fu… > > 2) We believe that there is a large number of OSProcess users that use > OSProcess only for executing OS commands AND popen() approach would be more > than enough (we will do a survey about this). So, a very simply solution via > FFI for these users rather than having all OSProcess, Command Shell, the > plugins etc, may be worth. > > What do you think? > >> >> Now, given some of the difficulties seen when dealing with external >> processes, I'd be wary of the "async" side of things. Random failures >> seemingly linked to signal loss are certainly not something I'd like to >> debug. >> > > Indeed, it won't be easy I guess. But sometimes the process you execute may > take quite some time and blocking the VM for that period is not a good > choice. So... what would you prefer to solve that? Do you prefer image-based > pooling as OSProcess does when IOPlugin is not used? How much might your work overlap with the Threaded FFI project for Cog?... ..."The Cog VM is single-threaded, providing green threads to the Smalltalk level, as do most Smalltalk VMs. There is a prototype subclass of the CoInterpreter, CoInterpreterMT, which provides a Python-like multi-threaded VM where any number of threads can share the VM with only one running the VM at any one time. This uses an extremely simple low-level scheme for releasing and re-acquiring ownership of the VM designed by David Simmons. This results in any and all FFI calls being non-blocking since there is such a low overhead to making a non-blocking FFI call that all FFI calls can be non-blocking. Eliot has worked on this, implementing the prototype and the reentrant FFI plugin it requires. But this needs to be revived. It would be a really powerful enhancement." cheers -ben P.S. Just another article warning against mixing fork and multiple-threads (which it seems posix_spawn may avoid)... http://www.linuxprogrammingblog.com/threads-and-fork-think-twice-before-usi…

3 5

A Suggested Promotion
by Torsten Bergmann Dec. 23, 2015

Dec. 23, 2015

Jecel Assumpcao Jr. wrote on squeak-dev: >>In fact, it could be an extremely stripped down Linux focused exclusively >>on running Squeak (like Dan Ingalls did for his weather station). One >>advantage of that is that the boot time would be much smaller than what >>people are used to. John Hylands wrote on squeak-dev >My brother and I have been experimenting with Tiny Core Linux, which is >available on the Pi as piCore. > >It boots in 12 seconds, from power on to login prompt, on a Pi 2. That >gives you wifi plus an openssh server. It would probably add a few seconds >to get a graphical shell running, which it also includes. Note that for Pharo there is a project from Mike Filonov (owner of pharocloud.com) which was initially called "PharoNOS". It is also based on TinyCore Linux, here x86 based directly booting into Pharo. A description and an downloadable ISO is available on [1]. Runs fine on VirtualBox. >From the name often people thought it was a project similar to "SqueakNOS" (but SqueakNOS boots into Squeak and needed no Linux or other underneath as even the drivers were written in Smalltalk). I guess therefore Mike renamed the project to "Pharocloud OS" now, he also made the build scripts available on [2]. I also did some experiments with Pharo on the Pi - described in an article on [3]. The result was similar: directly booting into the Pharo environment/ a Smalltalk application - but on the Pi. There is Raspbian underneath. A video is available on [4]. However: if there is now some interest in having a fast and direct Squeak/Pharo booting on the Pi maybe this could be a shared effort between both communities as well. Beside squeak-dev I therefore CC the pharo-dev mailinglist as well. Bye T. [1] http://pillarhub.pharocloud.com/hub/mikefilonov/pharonos [2] http://os.pharocloud.com [3] https://medium.com/concerning-pharo/pharo-pi-9eef257b6a21#.qgqg6765p [4] https://www.youtube.com/watch?v=sfxFqQIuawg

1 0