Re: Asynchronous programming

On 8/11/2016 11:55 PM, Lawrence D’Oliveiro wrote: On Friday, August 12, 2016 at 2:25:05 AM UTC+12, Terry Reedy wrote: When I read something like "Python finally acquired an event loop in 3.4" I wonder where people have been. The tk event loop has been in Python perhaps for 2 decades... As

Re: Asynchronous programming

On 08/11/2016 10:47 PM, Paul Rudin wrote: Steven D'Aprano writes: [...] In this case, all the work is pure computation, so I don't expect to save any time by doing this, because the work is still all being done in the same process/thread, not in parallel. It may even take a little bit

Re: Asynchronous programming

On Saturday, August 13, 2016 at 8:26:05 PM UTC+12, Marko Rauhamaa wrote: > ... (unless Python takes Linux's AIO API into use, which > would be groundbreaking). Last I looked, asynchronous I/O on Linux was still a work in progress. The whole POSIX API has been grounded in the assumption that all

Re: Asynchronous programming

On 08/11/2016 07:14 AM, Steven D'Aprano wrote: On Thu, 11 Aug 2016 03:06 pm, Paul Rubin wrote: The basic characteristic of asynchronous programming is that it involves changing all your usual blocking i/o calls to non-blocking ones, so your program can keep running as soon as your request

Re: Asynchronous programming

Marko Rauhamaa writes: > Also, one must be careful with file access, which is necessarily > blocking on linux (unless Python takes Linux's AIO API into use, which > would be groundbreaking). AIO is a possibility for i/o on an already-open file and I think there may be other

Re: Asynchronous programming

tabase API has yet been ported to asyncio, has it? That means database access is not yet quite usable with asyncio (or any other form of asynchronous programming). Also, one must be careful with file access, which is necessarily blocking on linux (unless Python takes Linux's AIO API into use,

Re: Asynchronous programming

Steven D'Aprano writes: >> await asyncio.sleep(0.2) # pretend to do some real work > That is *awesome*. Thank you for the example! Keep in mind that the above basically takes the task off the list of runnables for 0.2 seconds, so it sits doing nothing and

Re: Asynchronous programming

On Fri, 12 Aug 2016 03:47 pm, Paul Rudin wrote: > Steven D'Aprano writes: > >> Thanks to everyone who has answered, I think I'm slowly starting to get >> it now. Let's see if we can come up with a toy example that doesn't >> involve low-level socket programming :-)

Re: Asynchronous programming

Steven D'Aprano writes: > Thanks to everyone who has answered, I think I'm slowly starting to get it > now. Let's see if we can come up with a toy example that doesn't involve > low-level socket programming :-) > > Let me simulate a slow function call: > > > import

Re: Asynchronous programming

Steven D'Aprano writes: > How do I write work() so that it cooperatively multi-tasks with other ... > threads? processes? what the hell do we call these things? What does this > example become in the asynchronous world? If it's heavily computational then you have to

Re: Asynchronous programming

On Friday, August 12, 2016 at 2:25:05 AM UTC+12, Terry Reedy wrote: > When I read something like "Python finally acquired an event loop in > 3.4" I wonder where people have been. The tk event loop has been in > Python perhaps for 2 decades... As was pointed out to me just a few days ago,

Re: Asynchronous programming

On Fri, Aug 12, 2016 at 10:08 AM, Steven D'Aprano wrote: > Let me simulate a slow function call: > > > import random, time > > def work(id): > print("starting with id", id) > workload = random.randint(5, 15) > for i in range(workload): >

Re: Asynchronous programming

Thanks to everyone who has answered, I think I'm slowly starting to get it now. Let's see if we can come up with a toy example that doesn't involve low-level socket programming :-) Let me simulate a slow function call: import random, time def work(id): print("starting with id", id)

Re: Asynchronous programming

Steven D'Aprano writes: > But what's the point in doing it asynchronously if I have to just wait for > it to complete? > begin downloading in an async thread > twiddle thumbs, doing nothing > process download Suppose the remote server is overloaded so it sends

Re: Asynchronous programming

On Fri, Aug 12, 2016 at 12:55 AM, Steven D'Aprano wrote: > On Thu, 11 Aug 2016 02:41 pm, Chris Angelico wrote: > >> Consider these three ways of doing a database transaction: >> >> def synchronous(id): >> trn = conn.begin_transaction() >> trn.execute("select

Re: Asynchronous programming

On Thu, 11 Aug 2016 03:34 pm, Paul Rudin wrote: > Steven D'Aprano <steve+pyt...@pearwood.info> writes: > >> >> Is there a good beginner's tutorial introducing the basics of >> asynchronous programming? Starting with, why and where would you use it? > >

Re: Asynchronous programming

Steven D'Aprano writes: > > But what's the point in doing it asynchronously if I have to just wait for > it to complete? > > begin downloading in an async thread > twiddle thumbs, doing nothing > process download If you have nothing else to do, then there's no

Re: Asynchronous programming

Michael Selik writes: > On Thu, Aug 11, 2016 at 11:46 AM Michael Selik > wrote: > >> On Thu, Aug 11, 2016 at 11:01 AM Steven D'Aprano < >> steve+pyt...@pearwood.info> wrote: >> >>> That ... looks wrong. You're taking something which looks like a

Re: Asynchronous programming

On Thu, Aug 11, 2016 at 11:46 AM Michael Selik wrote: > On Thu, Aug 11, 2016 at 11:01 AM Steven D'Aprano < > steve+pyt...@pearwood.info> wrote: > >> That ... looks wrong. You're taking something which looks like a procedure >> in the first case (trn.execute), so it

Re: Asynchronous programming

On Thu, Aug 11, 2016 at 11:01 AM Steven D'Aprano wrote: > That ... looks wrong. You're taking something which looks like a procedure > in the first case (trn.execute), so it probably returns None, and yielding > over it. Even it that's not wrong, and it actually

Re: Asynchronous programming

On Thu, 11 Aug 2016 02:41 pm, Chris Angelico wrote: > Consider these three ways of doing a database transaction: > > def synchronous(id): > trn = conn.begin_transaction() > trn.execute("select name from people where id=%d", (id,)) > name, = trn.fetchone() > trn.execute("update

Re: Asynchronous programming

Steven D'Aprano : > Say I want to download data from a network, and it will take a long > time. If I can do the read in parallel to something else, that makes > sense: > > begin downloading in another thread/process > make a coffee > process download > > But

Re: Asynchronous programming

On Thu, 11 Aug 2016 03:06 pm, Paul Rubin wrote: > The basic characteristic of asynchronous programming is that it involves > changing all your usual blocking i/o calls to non-blocking ones, so your > program can keep running as soon as your request is started. That's the bit that confu

Re: Asynchronous programming

Steven D'Aprano : > Instructions unclear, poked myself in the eye with a sharp stick. I have updated my Dining Philosophers example for Python 3.5: http://pacujo.net/~marko/philosophers.py> It demonstrates how to get an event loop and start a number of asyncs

Re: Asynchronous programming

On 8/11/2016 2:34 AM, Christian Gollwitzer wrote: Am 11.08.16 um 06:38 schrieb Terry Reedy: You might be able to glean something from the succession of files I uploaded to https://bugs.python.org/issue27546 Integrate tkinter and asyncio (and async) I started with just mixing tk and asyncio

Re: Asynchronous programming

On Thu, 11 Aug 2016 07:33 pm, Chris Angelico wrote: > Yes, > threading bugs can be harder to debug; but only when you've violated > the other principles. Especially the principle "Avoid threaded programming". Some people, when faced with a problem, Now they think "I know, I'll have use two

Re: Asynchronous programming

On Thu, 11 Aug 2016 03:34 pm, Paul Rudin wrote: > Steven D'Aprano <steve+pyt...@pearwood.info> writes: > >> >> Is there a good beginner's tutorial introducing the basics of >> asynchronous programming? Starting with, why and where would you use it? > >

Re: Asynchronous programming

Chris Angelico : > On Thu, Aug 11, 2016 at 5:55 PM, Marko Rauhamaa wrote: >> My favorite asynchronous development model is the "callback hell," where >> each cell of the state/event matrix is represented by a method (or at >> least a switch case in C) and each

Re: Asynchronous programming

Chris Angelico writes: > On Thu, Aug 11, 2016 at 7:45 PM, Steven D'Aprano > wrote: >> I don't know whether you would call that a callback. I suppose it could be, >> in >> the sense that you might say: >> >>

Re: Asynchronous programming

On Thu, Aug 11, 2016 at 7:45 PM, Steven D'Aprano wrote: > I don't know whether you would call that a callback. I suppose it could be, in > the sense that you might say: > > button.set_mouseup_function(mouseUp) > > but I'm used to thinking of it as a

Re: Asynchronous programming

On Thursday 11 August 2016 16:21, Christian Gollwitzer wrote: > In typical GUI code, there are usually not that many places qhere ou > have sequential code. A simple exmaple might be a counter. Using asyncio > and a properly integrated GUI toolkit, you could write it as (pseudo-code) > > async

Re: Asynchronous programming

s that. (That's one of the advantages of Python's generator-based async model - although it's not perfect.) > Instead, I strongly prefer asynchronous programming and multiprocessing. Multiprocessing is *exactly* as complicated as multithreading, with the additional overhead of having to pass stat

Re: Asynchronous programming

g. * No cancellation. * Deadlocks and/or race conditions are virtually guaranteed. * Error symptoms are highly nonlocal making debugging very tricky. Instead, I strongly prefer asynchronous programming and multiprocessing. However, I'm afraid Python is following an unfortunate trend with asy

Re: Asynchronous programming

Christian Gollwitzer writes: > I'm convinced that it is possible to integrate Tcl's event loop with > asyncio's loop without regular update polling. This might require a > patch to Tkinter at the C level. For example, an easy way is to put > Tcl/Tk in it's own thread. ... I did

Re: Asynchronous programming

Am 11.08.16 um 06:38 schrieb Terry Reedy: You might be able to glean something from the succession of files I uploaded to https://bugs.python.org/issue27546 Integrate tkinter and asyncio (and async) I started with just mixing tk and asyncio callbacks. After some struggle with similar question

Re: Asynchronous programming

. Asynchronous programming is event based programming. In fact if you drop down to the C level, it works the same - you get callbacks when new data arives over a socket, or when a timer triggers. asyncio is just a way that makes writing stateful callback handlers easier, in the same way

Re: Asynchronous programming

Steven D'Aprano <steve+pyt...@pearwood.info> writes: > > Is there a good beginner's tutorial introducing the basics of asynchronous > programming? Starting with, why and where would you use it? You could do worse than watch Dave Beazley's pycon talk: https://www.youtube.com/watc

Re: Asynchronous programming

On Thu, Aug 11, 2016 at 3:06 PM, Paul Rubin wrote: > The basic reason to do it is it lets you serve a lot of concurrent i/o > channels (network connections, say) without using threads. If you want > to read a packet, you launch a non-blocking read that returns >

Re: Asynchronous programming

Steven D'Aprano <steve+pyt...@pearwood.info> writes: > Is there a good beginner's tutorial introducing the basics of asynchronous > programming? Starting with, why and where would you use it? You might look at some node.js tutorials since there are about a gazillion of them and some

Re: Asynchronous programming

On Thu, Aug 11, 2016 at 1:53 PM, Steven D'Aprano wrote: > How is this the same as, or different from, event-based programming? I'm > familiar with programming in an event-based language where the interpreter > itself provides an event loop and dispatches messages to

Re: Asynchronous programming

On 8/10/2016 11:53 PM, Steven D'Aprano wrote: The latest versions of Python are introducing new keywords for asynchronous programming, async and await. See PEP 492: https://www.python.org/dev/peps/pep-0492/ Is there a good beginner's tutorial introducing the basics of asynchronous programming

Asynchronous programming

The latest versions of Python are introducing new keywords for asynchronous programming, async and await. See PEP 492: https://www.python.org/dev/peps/pep-0492/ Is there a good beginner's tutorial introducing the basics of asynchronous programming? Starting with, why and where would you use

[ANN]: asyncoro: Framework for asynchronous programming with coroutines

I posted this message earlier to the list, but realized that URLs appear broken with '.' at the end of URL. Sorry for that mistake and this duplicate! asyncoro is a framework for developing concurrent programs with asynchronous event completions and coroutines. Asynchronous completions currently

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