[Vm-dev] re: Can OSProcess functionality be implemented using FFI instead of plugin?

Eliot Miranda eliot.miranda at gmail.com
Mon Jan 18 12:02:26 UTC 2016

Hi Dimitris,

> On Jan 18, 2016, at 3:29 AM, Dimitris Chloupis <kilon.alios at gmail.com> wrote:
> so I assume that means callbacks from inside C threads works fine which make it more than enough at least for now. 

C threads us a misnomer.  Callbacks from native threads that are currently calling out work.  I /think/ callbacks from native threads that have previously called out but are not currently calling out work, but am not sure.  Callbacks from native threads the VM has not seen before don't yet work; the VM doesn't service them.

> Does that mean that the VM will implement a real threading mechanism ? 

This is a mechanism that allows one to freely share the VM between arbitrary native threads but only one thread can run the VM at any one time.  So it provides true multi threading but it does /not/ provide concurrency.

>> On Mon, Jan 18, 2016 at 1:11 PM Craig Latta <craig at netjam.org> wrote:
>> > ...when Craig Latta tried to use [Alien FFI] late last year it worked
>> > up to a point.  The thing that didn't work was callbacks from foreign
>> > threads.  So it looks like the core threading code is not too far
>> > away from working.
>>      (Yes, it seemed close enough that I spent several hours debugging,
>> trying to get it the rest of the way. I ran out of time, so I wrote a
>> wrapper C library around the one I wanted to use, with threaded C
>> callback functions that signalled Smalltalk semaphores on which my
>> synchronous-FFI Smalltalk process waited. A hack, but it worked fine and
>> was simple.)
>> -C
>> --
>> Craig Latta
>> netjam.org
>> +31   6 2757 7177 (SMS ok)
>> + 1 415  287 3547 (no SMS)
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