dreeder


Hallo all.

Questions:

  . Does javascript play well with MSP?  Especially with regard to
    scheduling.  

  . Is there a threshhold of program complexity beyond which js
    objects become dangerous?

  . Opinions on which development languages best support multi-threaded
    data management?  mxj, C?  (Cursory glance at Java implies that
    only 2 threads are available: main vs. priority.)

MacOS 10.4.11 + Max/MSP/Jitter v.5.0.7.  (Eventually MacOS 10.5.*.)

I've developed a "multi-threaded" javascript environment: similar
data objects run in individual task objects, sharing memory.
They respond to one another per dynamic internal parameters and
external messages.  Presently, this program logic is intantiated
with a single js object.  (It does not share or query global objects.)

The main patch incorporating this js object is simple.  Data
tuples generated by the tasks are delvered to receive objects that
control oscillator envelopes.

Max crashes -- sometimes after 1 or 2 runs.  This did not occur
while prototyping a simpler version.

I'm _assuming_ javascript is the culprit...   And I'm humbly
_assuming_ my program is perfect. :)  To be sure, weak typing in
javascript does not aid the debugging process.

merci,
david


js-object-robustness-tasks

You can't create threads in JS. It's a piece of cake in Java, and a little bit more painful in C (although there's a cross platform way of doing it in the Max API, look at ext_systhread.h).

Good to know. The Max implementation of Java supports 

continuously runnnig code that arbitrarily spawns threads.

Is there a technical explanation for how Javascript Task objects are managed by the Max kernel? (a brief comparison to Java would also be helpful.)

Could you recommend which Java class(es) I should examine first 

to implement threading? (RTFM is okay, too. :)

Re: javascript. To be sure, I've implemented the task objects to great success. Max runs fine until I signal to stop/restart the flock more than "a few times." I will try to develop a unit 

I'm concerned that any sort of continuously running threaded code will conflict with Max scheduling (or something) -- or perhaps Max does not support threading, and was not intended

Good to know.  The Max implementation of Java supports 
continuously runnnig code that arbitrarily spawns threads.
(POSIX threading?)  

Is there a technical explanation for how Javascript Task objects are managed by the Max kernel?  (a brief comparison to Java would also be helpful.)

Could you recommend which Java class(es) I should examine first 
to implement threading?  (RTFM is okay, too. :)

Re: javascript.  To be sure, I've implemented the task objects to great success.  Max runs fine until I signal to stop/restart the flock more than "a few times."  I will try to develop a unit 
test that crashes the system.  

I'm concerned that any sort of continuously running threaded code will conflict with Max scheduling (or something) -- or perhaps Max does not support threading, and was not intended
to do so.

Automata spawns N threads which iterate once every MaxClock milliseconds preserving context between iterations. Threads run one or more arbitrary programs that return delay time until next iteration. Messages to the Automata object define program type, initial configuration and allow start/stop/replace for individual threads.

The original javascript version is in there as well.

If you find it useful, I'd love to have your feedback.

Automata spawns N threads which iterate once every MaxClock milliseconds preserving context between iterations.  Threads run one or more arbitrary programs that return delay time until next iteration.  Messages to the Automata object define program type, initial configuration and allow start/stop/replace for individual threads.  

The server was unable to complete your request.

" . Is there a threshhold of program complexity beyond which js

I'm working on code to route MIDI and control a show.

I've got a 500+ line js program running now (with additionally 200+ lines of test code so the test js file totals almost 800 lines) and I've experienced no stability issues at all - nor do I detect substantial delays in performance.

I have not tried anything involving processing audio signals, I'd expect that to simply not work.

Regarding Max crashing - I've had it happen quite a few times, and each time I tracked it down to my Javascript program doing "something wrong".

The usual culprit is an infinite loop, either in the code, or by sending something out that triggers another input, recursively.

You also need to be careful - there are two phases, the initialization phase when you can't talk to outlets, and then the rest of the JS object's life when you can.

If you try to talk to an outlet in initialization, this I believe has also crashed Max for me.

Typically, any box of complexity I write will do simple things in the initialization, and later do anything that requires outlets in response to a loadbang from the containing patch.

I've been pretty happy with my Javascript experience. It lets me write good tests and do table-driven design, which is really handy for music. I would only wish it to be Python (I've used the Python extension but JS is more built-in...)

" . Is there a threshhold of program complexity beyond which js
    objects become dangerous?"

I've got a 500+ line js program running now (with additionally 200+ lines of test code so the test js file totals almost 800 lines) and I've experienced no stability issues at all - nor do I detect substantial delays in performance.  

Regarding Max crashing - I've had it happen quite a few times, and each time I tracked it down to my Javascript program doing "something wrong".  

You also need to be careful - there are two phases, the initialization phase when you can't talk to outlets, and then the rest of the JS object's life when you can.  

I've been pretty happy with my Javascript experience.  It lets me write good tests and do table-driven design, which is really handy for music.  I would only wish it to be Python (I've used the Python extension but JS is more built-in...)


I have done everything but it still displays 404 Not Found

I have to say that I'm still not sure *why* you need threads in your Max/MSP Javascript.

Surely it's better to use the Max scheduler only than to have two separate schedulers? And there are always Max/MSP Javascript's "Tasks" objects if you need to schedule an event to happen at a future time.

It seems like unnecessary complexity. Is there a real application for it?

Surely it's better to use the Max scheduler only than to have two separate schedulers?  And there are always Max/MSP Javascript's "Tasks" objects if you need to schedule an event to happen at a future time.

It seems like unnecessary complexity.  Is there a real application for it?


Why? Shared memory between independent threads of execution which,

in turn, manage their own life cycle. I bet MaxClock is carefully

integrated into the subsystem that handles all other scheduling

needs. Intuition sez Javascript is primarily intended as

a layer of indirection for interface design and top-level object

Why?  Shared memory between independent threads of execution which,
in turn, manage their own life cycle.  I bet MaxClock is carefully
integrated into the subsystem that handles all other scheduling
needs.  Intuition sez Javascript is primarily intended as
a layer of indirection for interface design and top-level object
logic.


"Shared memory between independent threads of execution which, in turn, manage their own life cycle."

But this seems to beg the question. For what purpose do you need these independent threads of execution?

The Task class handles approximate scheduling quite well. If you want tight scheduling, there's really not better solution than Max itself.

I'm not sure I understand your answer... 

But this seems to beg the question.  For what purpose do you need these independent threads of execution?

The Task class handles approximate scheduling quite well.  If you want tight scheduling, there's really not better solution than Max itself.


I'm curious how fast the task object can run steadily. Eg, I have a program where I want to create a main loop to check for various things constantly, and this task function is set to repeat every 0,001 ms but it still misses some events (events that are of min. 150ms period, so it's very weird.)

Had a look today at this today. javascript isn't suitable for time sensitive events because they are treated as "low priority" in the scheduler. =/

js object robustness + tasks