Hmm... it "works" if I remove the first echo in the verb 'task'.
metcon=: {{
lock=: 10 T. 0
sleep=: 6!:3
task=: {{
NB. echo 'Task ',y,&":' waiting...'
11 T. lock NB. wait
sleep 2
echo r=.'Task ',y,&":' has the semaphore'
13 T. lock NB. release
r rplc 'has';'had'
}}
0&T.@'' each i.0>.4-1 T.'' NB. ensure at least four threads
echo (":1 T. ''),' threads'
r=. > task t.''"0 i.10 NB. dispatch and wait for 10 tasks
14 T. lock NB. discard lock
r
}}
metcon''
I put "works" in scare quotes because the timing of the remaining echo
statements seems wrong.
But this only happens under jqt -- when I run it from jconsole, the
timing between the echo statements seems uniform.
All of which suggests that there's something odd about the mechanism
used to send messages to jqt from threads other than the main thread.
Thanks,
--
Raul
On Wed, Jun 1, 2022 at 7:23 PM Raul Miller <[email protected]> wrote:
>
> The (10$0 1) # was to work around the value error -- it's debugging code.
>
> However, I get the crash after removing it entirely. This happens
> using f. and this happens with task defined as a global name:
>
> metcon=: {{
> lock=: 10 T. 0
> sleep=: 6!:3
> task=: {{
> echo 'Task ',y,&":' waiting...'
> 11 T. lock NB. wait
> sleep 2
> echo r=.'Task ',y,&":' has the semaphore'
> 13 T. lock NB. release
> r rplc 'has';'had'
> }}
> 0&T.@'' each i.0>.4-1 T.'' NB. ensure at least four threads
> echo (":1 T. ''),' threads'
> r=. > task t.''"0 i.10 NB. dispatch and wait for 10 tasks
> 14 T. lock NB. discard lock
> r
> }}
>
> Thanks,
>
> --
> Raul
>
>
> On Wed, Jun 1, 2022 at 7:19 PM Elijah Stone <[email protected]> wrote:
> >
> > Right... I was chasing the wrong issue. The code is wrong.
> >
> > The issue is that 'task' is a proverb, and the new thread does not inherit
> > metcon's lexical scope (which would be tantamount to closures...maybe not a
> > bad idea...), so 'task' is looked up globally, and found nowhere. Fixes
> > include making 'task' global (like 'lock' and 'sleep'), or using f. as I
> > suggested before.
> >
> > That the code appeared to work when not creating any threads is a bug.
> >
> > Incidentally, there is another issue: you destroy the mutex before ensuring
> > that all threads are done. I suggest transposing (10$0 1)&# and > .
> >
> > On Wed, 1 Jun 2022, Elijah Stone wrote:
> >
> > > BTW, 11 T.lock is equivalent to 11 T.lock;_ .
> > >
> > > On Wed, 1 Jun 2022, Raul Miller wrote:
> > >
> > >> Oops, bad copy and paste
> > >>
> > >> Ignore the first (incomplete) declaration of metcon.
> > >>
> > >> Actually, please treat the declaration at
> > >> http://www.jsoftware.com/pipermail/beta/2022-June/010566.html as
> > >> canonical for this issue.
> > >>
> > >> Thanks,
> > >>
> > >> --
> > >> Raul
> > >>
> > >> On Wed, Jun 1, 2022 at 3:57 PM Raul Miller <[email protected]> wrote:
> > >>>
> > >>> https://www.rosettacode.org/wiki/Metered_concurrency
> > >>>
> > >>> I wanted to put together a more serious J implementation of the
> > >>> rosettacode metered concurrency task.
> > >>>
> > >>> Unfortunately, either (a) I do not understand how the threading
> > >>> primitives are supposed to work, or (b) they are not working properly.
> > >>>
> > >>> metcon=: {{
> > >>> lock=: 10 T. 0
> > >>> sleep=: 6!:3
> > >>> metcon=: {{
> > >>> lock=: 10 T. 0
> > >>> sleep=: 6!:3
> > >>> task=. {{
> > >>> 11 T. lock;_ NB. wait
> > >>> sleep 2
> > >>> echo r=.'Task ',y,&":' has the semaphore'
> > >>> 13 T. lock NB. release
> > >>> r rplc 'has';'had'
> > >>> }}
> > >>> 0&T.@'' each i.0>4-1 T.'' NB. ensure at least four threads
> > >>> r=. task t.''"0 i.10 NB. dispatch 10 tasks
> > >>> #each r NB. wait for completion
> > >>> 14 T. lock NB. discard lock
> > >>> r
> > >>> }}
> > >>> I expect this to take about 20 seconds (because of the use of 6!:3)
> > >>> and run ten tasks in 3 of the four guaranteed threads.
> > >>>
> > >>> Instead, what I get is this:
> > >>>
> > >>> metcon''
> > >>> Task 1 has the semaphore
> > >>> Task 3 has the semaphore
> > >>> Task 5 has the semaphore
> > >>> Task 7 has the semaphore
> > >>> Task 9 has the semaphore
> > >>> |value error
> > >>> | #each r
> > >>>
> > >>> So it looks like half of my tasks are getting lost somewhere, and it
> > >>> looks like all of the results from those tasks are getting lost
> > >>> somewhere.
> > >>>
> > >>> JVERSION
> > >>> Engine: j904/j64avx2/windows
> > >>> Beta-d: commercial/2022-05-19T20:39:35
> > >>> Library: 9.04.01
> > >>> Qt IDE: 2.0.3/6.2.4(6.2.4)
> > >>> Platform: Win 64
> > >>> Installer: J904 install
> > >>> InstallPath: c:/other/j904
> > >>> Contact: www.jsoftware.com
> > >>>
> > >>> Thanks,
> > >>>
> > >>> --
> > >>> Raul
> > >> ----------------------------------------------------------------------
> > >> For information about J forums see http://www.jsoftware.com/forums.htm
> > > ----------------------------------------------------------------------
> > > For information about J forums see http://www.jsoftware.com/forums.htm
> > >
> > ----------------------------------------------------------------------
> > For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
