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

[Spec] Issue with toolbar button width

by Hilaire

Hi, I am sketching the final touch on what will be a DrGeo workspace for kids. I am using a dedicated toolbar and I have issue with the button label: they are cut and their width seem to be somehow maximized. See bellow: By the way, Spec is quite a productive framework. Good work. Hilaire -- Dr. Geo http://drgeo.eu

April 9, 2020

Re: [Pharo-dev] [Spec] Selected item in a list off screen

by Christophe Demarey

Hi Hilaire, You may want to follow https://github.com/pharo-spec/Spec/issues/866 . What you could do for now in your presenter is: self selectIndex: anInteger. self verticalAlignment desiredVisibleRow: anInteger. Hope this helps, Christophe > Le 9 avr. 2020 Ã 10:44, Esteban Lorenzano <estebanlm(a)gmail.com> a Ã©crit : > > Hi, > >> On 9 Apr 2020, at 10:17, Hilaire <hilaire(a)drgeo.eu> wrote: >> >> Thanks Esteban. There is not hurry. I just want to be sure about my own doing. >> >> I will now write a dedicated workspace to let kids write, save and execute easily DrGeo script. > > SpCodePresenter is your friend there :) > (And Iâm polishing details on it) > > Esteban > >> >> Hilaire >> >> Le 08/04/2020 Ã 22:00, Esteban Lorenzano a Ã©crit : >>> There is an ongoing bug about list selections, I hope to work on it tomorrow if time allows me. >> >> -- >> Dr. Geo >> http://drgeo.eu >> >> >> > >

April 9, 2020

Re: [Pharo-dev] [Vm-dev] Pony for the Pharo VM

by Ronie Salgado

Dear Shaping, You seem to misunderstand the problem. This is not a technical problem, but a political problem. The language seems very cool, but it still have to be proven in production by a large company that shows that is actually being used, it is maintained and will be keep being maintained for decades, which is something that can be said about about C/C++ (Many companies) and Rust (Mozilla) (Go (Google) is out of the question because of its mandatory garbage collector). All of the people already working on the VM has their own political and technical agendas, and they will continue working on that. Mathematical and safeness proofs are not enough. The usage of Slang is also bad on this regard, but with the difference that there is already an existing open source VM that works (and used by several companies), and making a new VM is a high risk endeavor from a technical point of view (and political and business also). This means that if you really want to use Pony for making a Pharo or Squeak VM, then you are going to have to make it yourself, or to pay someone else willing to do it. You will not be able convince the existing people to adopt a new language unless you have something running in that language that actually proves that is worth it to change. How complete is the documentation on the current Pharo VM? > Very incomplete. The best documentation is the code itself, then you have old wiki articles in the Squeak wikis, and some technical articles in Eliot Miranda and ClÃ©ment Bera blogs. There are some additional ongoing efforts on documenting the VM from the Pharo people: https://github.com/SquareBracketAssociates/Booklet-PharoVirtualMachine and here: https://github.com/pharo-open-documentation/pharo-wiki/tree/master/PharoVir… I also wrote a very simplistic vm in pure C that can load a Pharo 64 bits image, interpret the bytecodes here: https://github.com/ronsaldo/crankvm . This cannot be used for actually running Pharo because most of the primitives are not yet implemented. I wrote this mostly for documenting myself on how things work, and for getting into that I had to read several parts of the existing vm sources, and the blue book ( http://stephane.ducasse.free.fr/FreeBooks/BlueBook/Bluebook.pdf ). We are talking about different, but related things: you can write a Pony > program whose domain-level state-machine is wrong or unfinished and > therefore not working correctly. This is called *livelocking*. Itâs a > domain-level problem, not a system problem (for Pony). Livelocking is the > developerâs problem, not Ponyâs. Compiled Pony code cannot > deadlock/data-race. Itâs not possible. Dealing with livelocking > (programming a state machine thoroughly and correctly so that you get the > behavior you want and describe in your code) is the subject of a special > grammar and tool Iâm working on for state-machine based programming. This > would supplement or replace the system browser. Right now my approach to > state-machine creating is a grammatical discipline that works very well for > me. I use it in Smalltalk, increasingly, and tend not to code without it > anymore. I donât want to be limited to green threads, however, and > definitely donât want explicit concurrency management. I donât have that > much time to waste, and hope everyone reading this has been burnt badly > enough by concurrency bugs to have a similar view. > > > > You even need to model network and power failures in your state machine. > So the programming language may help you a lot with you concurrent, > distributed and fault tolerant system programming, but they are not a > silver bullet that guarantees that your system is actually going to be > correct. > > > > See above concerning the difference between livelock and deadlock. > Thanks for the correct terminology. But from the point of view of the user they are same. And a livelock seems to be far more dangerous than a traditional deadlock for which you already have some debugging tools that are relatively easy to use. You can create a pthread_mutex with deadlock detection for detecting bug, or run your program through valgrind for detecting race conditions and deadlocks. The point of this is that the language safety net is not enough, and in fact it could actually be dangerous because it can instill a false sense of safeness. That false sense of safeness can be very dangerous in real world projects with deadlines that have to be met, and non-technical managers which are going to underestimate the deadline far more on this false sense of safeness. And since in the real world deadlines have to bet met, bugs and incomplete solutions are simply shipped. > Can Sysmel manage many threads on many cores (running actor threads in > parallel, not just green-thread-concurrently on one core), whilst > guaranteeing no data-races, and switch automatically between actor-threads, > without blocking (no wasted CPU cycles), in 5 to 15 ns? Pony can do that > now. > > > > If Sysmel cannot do those operations, or cannot do them as fast, can you > add the abilities cost-effectively? They already work in Pony, and a very > active team drives the effort. > I am developing the language, and if I want or need I can create a minimal vm suitable for my purpose (I am not even trying to convince existing people to use it for now, I will when I have the next version of Woden running on it, and they will be able to just use a Pharo subset for scripting), for which I can adapt into my purposes and needs, which are currently only being fulfilled by C and C++ (and perhaps Rust, but I found it too complicated). I would just use C++ if it had runtime reflection, and easy to do, reliable and robust live programming support but it does not have these crucial features. You can implement live programming in C++ by serializing your program state, changing the dll with your code, and then deserialize your program state. Program state serialization is not easy. Real multi-threading on Sysmel is already supported when you use it without garbage collection (the language is strongly modeled after C++11 when used in this way). When you enable the GC for Smalltalk semantics, it is currently using the Boehm conservative GC (I am using it for getting things running), so the concurrency will be limited by the stop the world semantics of the GC. When I implement a proper GC, I will be able to dissociate threads that only use the native runtime from the GC. But for "many threads", and high parallelism, what I use is the GPU where Sysmel can also be used as a shading language by generating Spir-V for Vulkan consumption (for this the llvm backend is not used, it does not expose all of the required semantics, unless the changed it recently). As for the actor model and by default non-blocking semantics, I just do not care about them (for now) because I know they bring their own problem that can have their impact on other parts of system (e.g. non-blocking IO everywhere and by default, on operating systems that do not support it very well). Instead I prefer explicit semantics, and if the user wants actor, then implement them as just another library in the system. BTW: how do you implement an actor? with a message queue, and how do you implement a message queue? with a mutex and a condition variable. What about deadlock? you are only taking a single mutex on the queue, so you cannot have a deadlock, since you need at least two mutexes for the dead lock that are taken in a different order. If you have N mutexes, for not having a deadlock you only have to take these N mutexe in the same order. That sounds easy, but in the practice is not and you would have to sort the actual addresses of the mutexes, and in many cases you will realize that you need to take an additional mutex after having already taken other mutexes (I know it from practice). The mutex of the queue is always the one taken last, and that is why it is safe to use the queue for message passing. So, what is so special about these actor languages? they actually use a M:N threading model where they actually use green threads in order to multiplex multiple cooperative threads into the different cores of the CPU. They only need to create N native threads that are pinned into the different cores of the CPU (sched_setaffinity in Linux), and the green threads are created by allocating stack memory and having a simple trampoline that stores all of the caller saved registers in the stack, switches the stack pointer, restores these same registers and returns. BTW the operating system level context switching machinery is also implemented on the same way, but it could have some additional instructions for returning into unprivileged code. These 5 to 15 ns figures typically come from switching the stack. And with 64 bits addresses the simplest way for allocating the stack memory is by just allocating large uncommitted memory for the stack memory, or use some other fancier schemes (See here: https://blog.cloudflare.com/how-stacks-are-handled-in-go/ ). You would also need a task queue (or process queue in OS terminology) for not blocking the different actors when they are waiting for messages. There are several papers that discuss how to implement this task queue which tends to be the main bottleneck of these system. In the case of userspace, since the OS is not aware of you green threads, you also need asynchronous IO for everything so that an IO operation does not block all of the tasks that running in a single core (I believe that I read from a different mechanism from a paper from Go that is more flexible, but I forgot about it). If you do not actually need a coroutine, and model your actors in terms of a single function application that receives a single message and process it, then you only need a single stack. (Fetch message from queue, apply the function, done), and you do not even have that 5-15 ns overhead for stack switching (you may have another overhead on pushing the pending actor on the ready queue that could outweigh the performance advantage). This is similar to a traditional asynchronous job system for which you only need a thread pool. And this can also be implemented in C/C++. Best regards, Ronie El jue., 9 abr. 2020 a las 7:43, Shaping (<shaping(a)uurda.org>) escribiÃ³: > > > I have to admit that that language looks quite interesting, but it is not > appropriate for writing an actual VM. > > > > The point of the Pony language and concurrency model is to be able to > write *any program*, even a VM, at scale and use all of the cores, with > minimal programming effort (compared to what the developer must endure when > explicitly managing synchronization issues). > > > > One thing is having the actor object model for writing an application that > scales where it can be a very desirable property, but another thing is > writing a virtual machine where you have time constraints for the just in > time compiler in a single CPU to reduce initialization time. > > > > A VM is a program. You can write any program you want with Pony. The > heaps are already actor-centric and usually very tiny, just the way we need > them for high-performance, real-time apps: > > > > Orca: GC and Type System Co-Design for Actor Languages: > > > > > https://www.ponylang.io/media/papers/orca_gc_and_type_system_co-design_for_… > > > > Can you be more specific about which program construct cannot be written > in Pony or cannot be written to run fast enough? > > > > You can write as much asynchronous and synchronous code as you wish, where > and when you needed it. The balance point is yours, as the developer, to > choose. > > > > In fact, most of the methods are actually interpreted and they are only > compiled after being executed several times for reducing this startup time. > > > > Of course. But this is not a problem peculiar to Pony (or C or Rust > orâ¦). Itâs just another programming task needed in the context of VM > design. Note the comment about using both JIT and AOT, as desired, during > development. In any case, if you use Pony, use a state-machine (which we > all should do anyway). If the developer cannot or will not develop the > discipline needed to build state-machines, systematically, Pony or any > highly concurrent, actor-based programming model will only thwart and > frustrate him. We canât efficiently use all these cores without such a > programming model. > > > > I think I would start by using the Pony compiler from a Smalltalk browser > (mod the browser to accommodate the actors too). Source code in files, > searching, and scrolling are too inefficient. > > > > In this problem domain, the actor model and the thread safeness guaranteed > by it does not help you at all, and deadlocks can always be produced. > > > > This statement is incorrect in the case of Pony (but we have a terminology > problem; see below), and this was the main reason for the post. Here is > the gist again: *Deadlocks and data-races are not possible in a Pony > program that compiles.* This is mathematically guaranteed. You can > glean this fact from the videos or study the details in Pony papers. > > I did have deadlocks problems with synchronous messages in Erlang > > > > Pony is not Erlang. It is like Erlang is many ways, but vastly improved. > My qualified (âin the round, for startersâ) comparison was a mistake. I > should have omitted the whole comment. The Erlang/Pony comparison never > goes well. Pony is a different animal. And itâs seriously powerful. > Forget about Erlang. Really. Just forget about it. Use what was learnt > there, and implement it in Pony. > > > > which forced me to go into using asynchronous messages, but if you do not > model your domain state machine you could also end with a deadlock by using > asynchronous messages, or even worse, an inconsistent state such as an > incomplete credit card transaction in a highly distributed system! > > > > We are talking about different, but related things: you can write a Pony > program whose domain-level state-machine is wrong or unfinished and > therefore not working correctly. This is called *livelocking*. Itâs a > domain-level problem, not a system problem (for Pony). Livelocking is the > developerâs problem, not Ponyâs. Compiled Pony code cannot > deadlock/data-race. Itâs not possible. Dealing with livelocking > (programming a state machine thoroughly and correctly so that you get the > behavior you want and describe in your code) is the subject of a special > grammar and tool Iâm working on for state-machine based programming. This > would supplement or replace the system browser. Right now my approach to > state-machine creating is a grammatical discipline that works very well for > me. I use it in Smalltalk, increasingly, and tend not to code without it > anymore. I donât want to be limited to green threads, however, and > definitely donât want explicit concurrency management. I donât have that > much time to waste, and hope everyone reading this has been burnt badly > enough by concurrency bugs to have a similar view. > > > > You even need to model network and power failures in your state machine. > So the programming language may help you a lot with you concurrent, > distributed and fault tolerant system programming, but they are not a > silver bullet that guarantees that your system is actually going to be > correct. > > > > See above concerning the difference between livelock and deadlock. > > > > Going back to the task of developing a VM, you also need to be able to > perform dangerous memory accessing operations for at least the following > three tasks: > > 1. Implementing the garbage collector. > > > > Actually no; there is nothing dangerous here. In Pony, a separate heap > exists for each actor. These are generally tiny, and come and go quickly. > If they are not tiny or at least very simple/uniform in structure, they > should be made so by refactoring actor scope, until they are. Smallness > and clarity of purpose are the main criteria for determining whether youâve > written an actor well. Those two properties also greatly ease debugging of > the actor. If you have a big actor not factored as a network of smaller > ones, youâve done something wrong, or youâve just started your state > machine, and have some factoring yet to do. You still have classes, but > these are an organizational tool for synchronous code used by Actors and > their asynchronous behaviors. > > > > 2. Direct access to object slots for implementing the bytecode interpreter. > > > > Not a problem. Itâs just a program feature. So we write it as it needs > to be. > > > > 3. Copying compiled machine code into executable memory and performing > position dependent relocations. > > > > Doable. The Pony FFI works well even at this early stage. > > > > The machine code generation and installation can be separated in two stage > (the current VM just generates the code directly into the executable > memory), and in fact having these two separated stages for compilation and > installation is a requirement for operating systems that enforce W^X page > level permissions, specially if you want a concurrent VM. > > > > Then do that. > > > > You need to install the executable code in an atomic way, so you need to > suspend the threads while changing the executable permission into the > writable permission. You may get away of this restriction if you are > allowed to map the same physical memory into different virtual addresses > ranges with different permissions (one writeable, and one executable). > > > > â¦as needed. > > > > Pony is changing quickly: https://ponylang.zulipchat.com/. > > > > Itâs being improved weekly. The Pony group are also working on a security > model (to deal with attacks via FFI and other sources), but this will be > some time coming. Feel free to contribute. The language is highly > moldable, especially at this stage. I think the version is 0.33. If you > need a feature or convenience not present, request it. The group is very > responsive, and eager to improve the tool. > > If there were no Smalltalk, I would certainly use Pony before C, Rust, or > Go, even at this early pre-1.0 stage. > > > > For these reasons, you need an unsafe language such as C/C++ for at least > these tasks, or a language that allows you to turn off the type and memory > safeness net. I heard that Rust has an unsafe pointer that you could also > for these purposes. > > > > The Pony FFI will work here. C libs are sometimes needed, and operations > in C code are of course not guaranteed to be safe, in any case. > > > > The Pharo team is going with the existing virtual machine for quite a > while. You cannot just replace something that is not well documented by > something new, specially when you do not have that many resources for > making a new vm. > > > > One of the main drivers in the choice of Pony is to reduce the resources > needed to create a highly performant, simple VM. One notable, > Pharo/Smalltalk-related problem for high-speed apps is stop-the-world GCing > in the one large system heap. This wonât work for high-performance, highly > concurrent, highly scalable apps, especially not for for real-time ones, > and *must go away*, if latencies approaching deterministic are to be > achieved. Pony has already solved this problem with per-actor heaps. That > design feature is very interesting because it represents much hard work > that need not be done. > > > > > > You first need to document completely the existing one, the semantics of > the bytecodes, how they are implemented, and also the same with the > primitives. > > > > Agreed. Iâm not claiming that VM development is easy or trivial, > generally or via Pony. VMs are arguably one of the most complicated things > that humans create (*not a compliment*). But Pony solves more > concurrency-related problems at compile-time than any other available tool. > > > > How complete is the documentation on the current Pharo VM? > > > > As for myself, I am putting my bets on another language that I am > developing (Sysmel: https://github.com/ronsaldo/sysmel ), and in full > ahead-of-time compilation, but my problem domain is video game programming, > low-level operating system, driver development and embedded programming > where I actually want to have control of the machine. > > > > Iâve read some on Sysmel. It appears to be an outstanding tool. > > > > Does Sysmel implement multicore concurrency, and guarantee no > deadlocks/data-races on compile? > > Pony, the language and concurrency model, will not stop us from doing > anything that can be done with the machine and OS. The Pony language is > not as interesting to me as its concurrency model. Donât like Pony syntax > (and I donât)? Then fork and change it. You have all the source. (Iâd > prefer to see keyword selectors everywhere, even without the usual > attendant polymorphism. Seriously.) > > > > Since I have written my compiler in Pharo, I can just reuse the Opal > Compiler for doing AST to AST translation and just compile Pharo (with some > limitations, for example no thisContext) into my runtime environment. If I > want a more dynamic environment, I can also serialize a Pharo > CompiledMethod, send it through a socket and then interpret it on the > Sysmel side: > https://github.com/ronsaldo/sysmel/blob/master/module-sources/Sysmel.Core/S… > by just reusing the existing language semantics. Currently although I am > just supporting Linux, and Windows support is coming in a couple of weeks > after getting a proper module system working for reducing compilation > times. For the backend I am using LLVM, wasm is not yet supported because I > am generating some IR that are not supported by the wasm backend > > > > Wasm and WASI will be good when they are ready. > > > > (vtable layouts, and some intrinsics that I am using for non-local > returns), but they should not be that complicated to fix. > > > > Can Sysmel manage many threads on many cores (running actor threads in > parallel, not just green-thread-concurrently on one core), whilst > guaranteeing no data-races, and switch automatically between actor-threads, > without blocking (no wasted CPU cycles), in 5 to 15 ns? Pony can do that > now. > > > > If Sysmel cannot do those operations, or cannot do them as fast, can you > add the abilities cost-effectively? They already work in Pony, and a very > active team drives the effort. > > > > > > Best, > > > > Shaping > > > > > > > > > > El lun., 6 abr. 2020 a las 6:05, Shaping (<shaping(a)uurda.org>) escribiÃ³: > > I should have initially posted this to the Pharo-dev list, as well. > > > > *From:* Pharo-users [mailto:pharo-users-bounces@lists.pharo.org] *On > Behalf Of *Shaping > *Sent:* Friday, 3 April, 2020 14:05 > *To:* 'Any question about pharo is welcome' <pharo-users(a)lists.pharo.org> > *Subject:* Re: [Pharo-users] Latest PharoJS Success Story; Wasm/WASI; > very keen on Pony for the Pharo VM > > > > All: > > > Brain Treats got stuck during launch on my LG. > > > > > Which android version are you using ? > > > > The phone is old and this is likely the problem. > > > > Android version: 4.4.2 > > Kernel version: 3.4.0 > > > > > Is there a plan to move PharoJS to Wasm/WASI? > > > > > Dave and I talked about it a long time ago. This sounds like a good idea. > > Actually, Dave has a very ambition idea = turn PharoJS into Pharo* where * > can be different targets. > > But, there's a lot to do before reaching this goal. So, don't expect it > any time soon. > > > > Not to change the topic too much, but the following is related and I often > think of itâ¦ > > > > Consider writing the pharo VM in Wasm or, better, with *Pony* (which can > emit Wasm, as needed). Ponyâs reference-capability-based (ref-cap) > concurrency-model guarantees provably that no data-races or deadlocks can > happen if the code compiles; this solves a very large class of extremely > ugly concurrency problems that no one ever wants to face. > > > > Pony gives high-performance concurrency (5 to 15 ns actor-thread switching > time, depending on platform), and solves the most difficult class of > synchronization problems at compile time. It runs as fast as C. It runs > faster than C, as concurrency scales. You canât scale a highly concurrent > app efficiently in C, and really shouldnât try if you wish to remain happy > and mentally healthy. > > > > Pony is still pre-1.0, but the group is very active and competent. I > think we should consider using it to build the VM. Have a look. Some > videos for your amusement and information: > > > > > > https://www.youtube.com/watch?v=ODBd9S1jV2s > > https://www.youtube.com/watch?v=u1JfYa413fY > > https://www.youtube.com/watch?v=fNdnr1MUXp8 > > https://www.ponylang.io/ > > > > There are many others. I mentioned the Pony concurrency architecture > around the holidays, but there was no interest from the listânot a good > time perhaps. > > > > The tentative plan is to do what Google does with Flutter: have the JIT > in support of the usual dynamicity a Smalltalker needs for rapid > development; and have AOT, fully optimized compiling for production or > speed-related reality checks, presumably needed less often during > development. There are other possibilities. > > > > Anyone interested? > > > > I have some ideas for simplifying use of the six ref caps in the context > of Pharo/Smalltalk. If this path is chosen, one must commit to strict > state-machine-based algorithm development, without exception. This should > have happened anyway by now, broadly in the programming space, but didnât. > Iâm working on a programming graphical tool and associated grammar (in VW) > that make state-machine development easy and attractive. This , besides > efficient use of machine resources, is the other reason for pushing in this > direction. > > > > A Pony program is built from a net of asynchronously communicating > actors. You change the state of your program with asynchronous messaging > between actors. There is no blocking--no mutexes or semaphoresâand > therefore no wasted CPU cycles or mushrooming program complexity, as you > try to use mutexes in a fine-grained way (a very bad idea). And as > mentioned, there are never deadlocks or data-races. All cores on all CPUs > stay busy, always, until the program goes idle or exits. The Pony group is > also working on extending the model to the network level, so that all > machine nodes in the network stay busy. In the round, as a start, think of > Pony as Erlang/OTP, but much faster, with no legacy bugs, and provably > no-deadlocking on compile. > > > > The asynchronous actor model is the programming pattern that Kay had in > mind when he said âobject-oriented.â Itâs the one I want to implement in > Pharo. The green threads are light, but donât efficiently use the cores, > and a net of VMs with their respective images still communicate too slowly. > > > > I your time permits, please study Pony for a bit, before rejecting the > idea as too big a change in direction or too complicated. Using Pony looks > like the ideal VM simplification strategy, if our aim is efficient use of > networks of machines, each with at least one CPU (often more), each, in > turn, with many cores (whose numbers are still increasing). This pattern > in hardware probably wonât be changing much, now that speeds are topping > out. Winning the performance game is therefore about efficiently using > many cores at once, *without burdening the programmer*. I donât see a > better way to do this now than with Pony. > > > > Thoughts and suggestions are welcome. > > > > > > Shaping > > > > > > > > > > > -----Original Message----- > > > From: Pharo-users [mailto:pharo-users-bounces@lists.pharo.org > <pharo-users-bounces(a)lists.pharo.org>] On > > > Behalf Of N. Bouraqadi > > > Sent: Tuesday, 28 January, 2020 12:18 > > > To: Any question about pharo is welcome <pharo-users(a)lists.pharo.org> > > > Subject: [Pharo-users] Latest PharoJS Success Story > > > > > > The latest PharoJS-powered smartphone app is now live. > > > Development has been made using Pharo. > > > Then, javascript code is generated using PharoJS. > > > Last, the app is built to target both iOS and Android thanks to Apache > > > Cordova. > > > > > > Learn more and Download at > > > https://nootrix.com/projects/brain-treats-app/ > > > > > > Noury > > > > > > > > > > > >

April 9, 2020

Re: [Pharo-dev] [Spec] Selected item in a list off screen

by Esteban Lorenzano

Hi, > On 9 Apr 2020, at 10:17, Hilaire <hilaire(a)drgeo.eu> wrote: > > Thanks Esteban. There is not hurry. I just want to be sure about my own doing. > > I will now write a dedicated workspace to let kids write, save and execute easily DrGeo script. SpCodePresenter is your friend there :) (And Iâm polishing details on it) Esteban > > Hilaire > > Le 08/04/2020 Ã 22:00, Esteban Lorenzano a Ã©crit : >> There is an ongoing bug about list selections, I hope to work on it tomorrow if time allows me. > > -- > Dr. Geo > http://drgeo.eu > > >

April 9, 2020

Re: [Pharo-dev] [Spec] Selected item in a list off screen

by Hilaire

Thanks Esteban. There is not hurry. I just want to be sure about my own doing. I will now write a dedicated workspace to let kids write, save and execute easily DrGeo script. Hilaire Le 08/04/2020 Ã 22:00, Esteban Lorenzano a Ã©critÂ : > There is an ongoing bug about list selections, I hope to work on it tomorrow if time allows me. -- Dr. Geo http://drgeo.eu

April 9, 2020

Pony for the Pharo VM

by Shaping

I have to admit that that language looks quite interesting, but it is not appropriate for writing an actual VM. The point of the Pony language and concurrency model is to be able to write any program, even a VM, at scale and use all of the cores, with minimal programming effort (compared to what the developer must endure when explicitly managing synchronization issues). One thing is having the actor object model for writing an application that scales where it can be a very desirable property, but another thing is writing a virtual machine where you have time constraints for the just in time compiler in a single CPU to reduce initialization time. A VM is a program. You can write any program you want with Pony. The heaps are already actor-centric and usually very tiny, just the way we need them for high-performance, real-time apps: Orca: GC and Type System Co-Design for Actor Languages: https://www.ponylang.io/media/papers/orca_gc_and_type_system_co-design_for_… Can you be more specific about which program construct cannot be written in Pony or cannot be written to run fast enough? You can write as much asynchronous and synchronous code as you wish, where and when you needed it. The balance point is yours, as the developer, to choose. In fact, most of the methods are actually interpreted and they are only compiled after being executed several times for reducing this startup time. Of course. But this is not a problem peculiar to Pony (or C or Rust orâ¦). Itâs just another programming task needed in the context of VM design. Note the comment about using both JIT and AOT, as desired, during development. In any case, if you use Pony, use a state-machine (which we all should do anyway). If the developer cannot or will not develop the discipline needed to build state-machines, systematically, Pony or any highly concurrent, actor-based programming model will only thwart and frustrate him. We canât efficiently use all these cores without such a programming model. I think I would start by using the Pony compiler from a Smalltalk browser (mod the browser to accommodate the actors too). Source code in files, searching, and scrolling are too inefficient. In this problem domain, the actor model and the thread safeness guaranteed by it does not help you at all, and deadlocks can always be produced. This statement is incorrect in the case of Pony (but we have a terminology problem; see below), and this was the main reason for the post. Here is the gist again: Deadlocks and data-races are not possible in a Pony program that compiles. This is mathematically guaranteed. You can glean this fact from the videos or study the details in Pony papers. I did have deadlocks problems with synchronous messages in Erlang Pony is not Erlang. It is like Erlang is many ways, but vastly improved. My qualified (âin the round, for startersâ) comparison was a mistake. I should have omitted the whole comment. The Erlang/Pony comparison never goes well. Pony is a different animal. And itâs seriously powerful. Forget about Erlang. Really. Just forget about it. Use what was learnt there, and implement it in Pony. which forced me to go into using asynchronous messages, but if you do not model your domain state machine you could also end with a deadlock by using asynchronous messages, or even worse, an inconsistent state such as an incomplete credit card transaction in a highly distributed system! We are talking about different, but related things: you can write a Pony program whose domain-level state-machine is wrong or unfinished and therefore not working correctly. This is called livelocking. Itâs a domain-level problem, not a system problem (for Pony). Livelocking is the developerâs problem, not Ponyâs. Compiled Pony code cannot deadlock/data-race. Itâs not possible. Dealing with livelocking (programming a state machine thoroughly and correctly so that you get the behavior you want and describe in your code) is the subject of a special grammar and tool Iâm working on for state-machine based programming. This would supplement or replace the system browser. Right now my approach to state-machine creating is a grammatical discipline that works very well for me. I use it in Smalltalk, increasingly, and tend not to code without it anymore. I donât want to be limited to green threads, however, and definitely donât want explicit concurrency management. I donât have that much time to waste, and hope everyone reading this has been burnt badly enough by concurrency bugs to have a similar view. You even need to model network and power failures in your state machine. So the programming language may help you a lot with you concurrent, distributed and fault tolerant system programming, but they are not a silver bullet that guarantees that your system is actually going to be correct. See above concerning the difference between livelock and deadlock. Going back to the task of developing a VM, you also need to be able to perform dangerous memory accessing operations for at least the following three tasks: 1. Implementing the garbage collector. Actually no; there is nothing dangerous here. In Pony, a separate heap exists for each actor. These are generally tiny, and come and go quickly. If they are not tiny or at least very simple/uniform in structure, they should be made so by refactoring actor scope, until they are. Smallness and clarity of purpose are the main criteria for determining whether youâve written an actor well. Those two properties also greatly ease debugging of the actor. If you have a big actor not factored as a network of smaller ones, youâve done something wrong, or youâve just started your state machine, and have some factoring yet to do. You still have classes, but these are an organizational tool for synchronous code used by Actors and their asynchronous behaviors. 2. Direct access to object slots for implementing the bytecode interpreter. Not a problem. Itâs just a program feature. So we write it as it needs to be. 3. Copying compiled machine code into executable memory and performing position dependent relocations. Doable. The Pony FFI works well even at this early stage. The machine code generation and installation can be separated in two stage (the current VM just generates the code directly into the executable memory), and in fact having these two separated stages for compilation and installation is a requirement for operating systems that enforce W^X page level permissions, specially if you want a concurrent VM. Then do that. You need to install the executable code in an atomic way, so you need to suspend the threads while changing the executable permission into the writable permission. You may get away of this restriction if you are allowed to map the same physical memory into different virtual addresses ranges with different permissions (one writeable, and one executable). â¦as needed. Pony is changing quickly: https://ponylang.zulipchat.com/. Itâs being improved weekly. The Pony group are also working on a security model (to deal with attacks via FFI and other sources), but this will be some time coming. Feel free to contribute. The language is highly moldable, especially at this stage. I think the version is 0.33. If you need a feature or convenience not present, request it. The group is very responsive, and eager to improve the tool. If there were no Smalltalk, I would certainly use Pony before C, Rust, or Go, even at this early pre-1.0 stage. For these reasons, you need an unsafe language such as C/C++ for at least these tasks, or a language that allows you to turn off the type and memory safeness net. I heard that Rust has an unsafe pointer that you could also for these purposes. The Pony FFI will work here. C libs are sometimes needed, and operations in C code are of course not guaranteed to be safe, in any case. The Pharo team is going with the existing virtual machine for quite a while. You cannot just replace something that is not well documented by something new, specially when you do not have that many resources for making a new vm. One of the main drivers in the choice of Pony is to reduce the resources needed to create a highly performant, simple VM. One notable, Pharo/Smalltalk-related problem for high-speed apps is stop-the-world GCing in the one large system heap. This wonât work for high-performance, highly concurrent, highly scalable apps, especially not for for real-time ones, and must go away, if latencies approaching deterministic are to be achieved. Pony has already solved this problem with per-actor heaps. That design feature is very interesting because it represents much hard work that need not be done. You first need to document completely the existing one, the semantics of the bytecodes, how they are implemented, and also the same with the primitives. Agreed. Iâm not claiming that VM development is easy or trivial, generally or via Pony. VMs are arguably one of the most complicated things that humans create (not a compliment). But Pony solves more concurrency-related problems at compile-time than any other available tool. How complete is the documentation on the current Pharo VM? As for myself, I am putting my bets on another language that I am developing (Sysmel: https://github.com/ronsaldo/sysmel ), and in full ahead-of-time compilation, but my problem domain is video game programming, low-level operating system, driver development and embedded programming where I actually want to have control of the machine. Iâve read some on Sysmel. It appears to be an outstanding tool. Does Sysmel implement multicore concurrency, and guarantee no deadlocks/data-races on compile? Pony, the language and concurrency model, will not stop us from doing anything that can be done with the machine and OS. The Pony language is not as interesting to me as its concurrency model. Donât like Pony syntax (and I donât)? Then fork and change it. You have all the source. (Iâd prefer to see keyword selectors everywhere, even without the usual attendant polymorphism. Seriously.) Since I have written my compiler in Pharo, I can just reuse the Opal Compiler for doing AST to AST translation and just compile Pharo (with some limitations, for example no thisContext) into my runtime environment. If I want a more dynamic environment, I can also serialize a Pharo CompiledMethod, send it through a socket and then interpret it on the Sysmel side: https://github.com/ronsaldo/sysmel/blob/master/module-sources/Sysmel.Core/S… by just reusing the existing language semantics. Currently although I am just supporting Linux, and Windows support is coming in a couple of weeks after getting a proper module system working for reducing compilation times. For the backend I am using LLVM, wasm is not yet supported because I am generating some IR that are not supported by the wasm backend Wasm and WASI will be good when they are ready. (vtable layouts, and some intrinsics that I am using for non-local returns), but they should not be that complicated to fix. Can Sysmel manage many threads on many cores (running actor threads in parallel, not just green-thread-concurrently on one core), whilst guaranteeing no data-races, and switch automatically between actor-threads, without blocking (no wasted CPU cycles), in 5 to 15 ns? Pony can do that now. If Sysmel cannot do those operations, or cannot do them as fast, can you add the abilities cost-effectively? They already work in Pony, and a very active team drives the effort. Best, Shaping El lun., 6 abr. 2020 a las 6:05, Shaping (<shaping(a)uurda.org <mailto:shaping@uurda.org> >) escribiÃ³: I should have initially posted this to the Pharo-dev list, as well. From: Pharo-users [mailto:pharo-users-bounces@lists.pharo.org <mailto:pharo-users-bounces@lists.pharo.org> ] On Behalf Of Shaping Sent: Friday, 3 April, 2020 14:05 To: 'Any question about pharo is welcome' <pharo-users(a)lists.pharo.org <mailto:pharo-users@lists.pharo.org> > Subject: Re: [Pharo-users] Latest PharoJS Success Story; Wasm/WASI; very keen on Pony for the Pharo VM All: > Brain Treats got stuck during launch on my LG. > Which android version are you using ? The phone is old and this is likely the problem. Android version: 4.4.2 Kernel version: 3.4.0 > Is there a plan to move PharoJS to Wasm/WASI? > Dave and I talked about it a long time ago. This sounds like a good idea. Actually, Dave has a very ambition idea = turn PharoJS into Pharo* where * can be different targets. But, there's a lot to do before reaching this goal. So, don't expect it any time soon. Not to change the topic too much, but the following is related and I often think of itâ¦ Consider writing the pharo VM in Wasm or, better, with Pony (which can emit Wasm, as needed). Ponyâs reference-capability-based (ref-cap) concurrency-model guarantees provably that no data-races or deadlocks can happen if the code compiles; this solves a very large class of extremely ugly concurrency problems that no one ever wants to face. Pony gives high-performance concurrency (5 to 15 ns actor-thread switching time, depending on platform), and solves the most difficult class of synchronization problems at compile time. It runs as fast as C. It runs faster than C, as concurrency scales. You canât scale a highly concurrent app efficiently in C, and really shouldnât try if you wish to remain happy and mentally healthy. Pony is still pre-1.0, but the group is very active and competent. I think we should consider using it to build the VM. Have a look. Some videos for your amusement and information: https://www.youtube.com/watch?v=ODBd9S1jV2s https://www.youtube.com/watch?v=u1JfYa413fY https://www.youtube.com/watch?v=fNdnr1MUXp8 https://www.ponylang.io/ There are many others. I mentioned the Pony concurrency architecture around the holidays, but there was no interest from the listânot a good time perhaps. The tentative plan is to do what Google does with Flutter: have the JIT in support of the usual dynamicity a Smalltalker needs for rapid development; and have AOT, fully optimized compiling for production or speed-related reality checks, presumably needed less often during development. There are other possibilities. Anyone interested? I have some ideas for simplifying use of the six ref caps in the context of Pharo/Smalltalk. If this path is chosen, one must commit to strict state-machine-based algorithm development, without exception. This should have happened anyway by now, broadly in the programming space, but didnât. Iâm working on a programming graphical tool and associated grammar (in VW) that make state-machine development easy and attractive. This , besides efficient use of machine resources, is the other reason for pushing in this direction. A Pony program is built from a net of asynchronously communicating actors. You change the state of your program with asynchronous messaging between actors. There is no blocking--no mutexes or semaphoresâand therefore no wasted CPU cycles or mushrooming program complexity, as you try to use mutexes in a fine-grained way (a very bad idea). And as mentioned, there are never deadlocks or data-races. All cores on all CPUs stay busy, always, until the program goes idle or exits. The Pony group is also working on extending the model to the network level, so that all machine nodes in the network stay busy. In the round, as a start, think of Pony as Erlang/OTP, but much faster, with no legacy bugs, and provably no-deadlocking on compile. The asynchronous actor model is the programming pattern that Kay had in mind when he said âobject-oriented.â Itâs the one I want to implement in Pharo. The green threads are light, but donât efficiently use the cores, and a net of VMs with their respective images still communicate too slowly. I your time permits, please study Pony for a bit, before rejecting the idea as too big a change in direction or too complicated. Using Pony looks like the ideal VM simplification strategy, if our aim is efficient use of networks of machines, each with at least one CPU (often more), each, in turn, with many cores (whose numbers are still increasing). This pattern in hardware probably wonât be changing much, now that speeds are topping out. Winning the performance game is therefore about efficiently using many cores at once, without burdening the programmer. I donât see a better way to do this now than with Pony. Thoughts and suggestions are welcome. Shaping > -----Original Message----- > From: Pharo-users [ <mailto:pharo-users-bounces@lists.pharo.org> mailto:pharo-users-bounces@lists.pharo.org] On > Behalf Of N. Bouraqadi > Sent: Tuesday, 28 January, 2020 12:18 > To: Any question about pharo is welcome < <mailto:pharo-users@lists.pharo.org> pharo-users(a)lists.pharo.org> > Subject: [Pharo-users] Latest PharoJS Success Story > > The latest PharoJS-powered smartphone app is now live. > Development has been made using Pharo. > Then, javascript code is generated using PharoJS. > Last, the app is built to target both iOS and Android thanks to Apache > Cordova. > > Learn more and Download at > <https://nootrix.com/projects/brain-treats-app/> https://nootrix.com/projects/brain-treats-app/ > > Noury > >

April 9, 2020

Re: [Pharo-dev] [Spec] Selected item in a list off screen

by Esteban Lorenzano

Hi Hilaire, There is an ongoing bug about list selections, I hope to work on it tomorrow if time allows me. Esteban > On 8 Apr 2020, at 19:54, Hilaire <hilaire(a)drgeo.eu> wrote: > > So this is the normal behavior? > > I am not missing anything ? > > Hilaire > > Le 04/04/2020 Ã 19:57, Hilaire a Ã©crit : >> >> Hi, >> >> When I programmatically selects an item in a presenter list *and* when this item is off screen -- for example at the end of a long list -- the list widget is not scrolled to make it visible. >> >> (DrGScriptBrowser2 new script: DrGeoUserScript allSubclasses last; yourself) openWithSpec >> >> Is it a bug or am I missing something >> >> Thanks >> >> Hilaire >> >> -- >> Dr. Geo >> http://drgeo.eu > > -- > Dr. Geo > http://drgeo.eu > > >

April 8, 2020

Re: [Pharo-dev] [Spec] Selected item in a list off screen

by Hilaire

So this is the normal behavior? I am not missing anything ? Hilaire Le 04/04/2020 Ã 19:57, Hilaire a Ã©critÂ : > > Hi, > > When I programmatically selects an item in a presenter list *and* when > this item is off screen -- for example at the end of a long list -- > the list widget is not scrolled to make it visible. > > (DrGScriptBrowser2 new script: DrGeoUserScript allSubclasses last; > yourself) openWithSpec > > Is it a bug or am I missing something > > Thanks > > Hilaire > > -- > Dr. Geo > http://drgeo.eu -- Dr. Geo http://drgeo.eu

April 8, 2020

Re: [Pharo-dev] Cover for PBE8

by Alexandre Bergel

I like the mosaic Alexandre -- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.bergel.eu ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;. > On Apr 7, 2020, at 8:31 AM, CÃ©drick BÃ©ler <cdrick65(a)gmail.com> wrote: > > Just a try. > > I searched for free picture around the words lighthouse and/or (mosaic patchwork painterâ¦). > A bit like this one (which is not free). > <GraphiqueCollÃ©-4.png> > > > Also, I kind of like the spiral effect which evoke practicing the internalâ¦ and the spiral effet (learning/getting better). > https://www.flickr.com/photos/28752865@N08/19369475232 <https://www.flickr.com/photos/28752865@N08/19369475232> > > There are some other free and available. This one is Creative Commons: > https://www.flickr.com/photos/kaptainkobold/6699472801 <https://www.flickr.com/photos/kaptainkobold/6699472801> > <GraphiqueCollÃ©-2.png> > => google image searches <https://www.google.com/search?q=lighthouse+inside+stairs&tbm=isch&ved=2ahUK…> on Â« free Â» internal stairs. > > > I also searched for Â« lighthouse anatomy / internals Â». Itâs nice but donât think usable out of the box. It should be stylized (and eventually adapted to programming internals). > https://commons.wikimedia.org/wiki/File:Antique_-_Maniguin_Lighthouse_-_Ori… <https://commons.wikimedia.org/wiki/File:Antique_-_Maniguin_Lighthouse_-_Ori…>. Section_of_new_Eddystone_Lighthouse.jpg <https://upload.wikimedia.org/wikipedia/commons/7/74/Section_of_new_Eddyston…>. > > > My 2 cents, > CÃ©drick (preference for the spiral effect) >

April 8, 2020

[Pharo 9.0] Build #229: ReflectivityAfterOptimizedBlocks

by ci-pharo-ci-jenkins2＠inria.fr

There is a new Pharo build available! The status of the build #229 was: SUCCESS. The Pull Request #6153 was integrated: "ReflectivityAfterOptimizedBlocks" Pull request url: https://github.com/pharo-project/pharo/pull/6153 Issue Url: https://github.com/pharo-project/pharo/issues/ReflectivityAfterOptimizedBlo… Build Url: https://ci.inria.fr/pharo-ci-jenkins2/job/Test%20pending%20pull%20request%2…

April 8, 2020