It seems your primary question has been answered. I will add: I strongly
suggest using a conjunction to lock your mutex; something similar to what I
demonstrated in the 'unwind protect' thread, as the alternative is pretty much
impossible to get right in the general case.
On Tue, 10 May 2022, Devon McCormick wrote:
Henry,
Here is the MVF - minimum viable failure. It looks like the culprit is
"read_image" which is just a cover for "readimg_jqtide_". I'm running
under jconsole.
Set up in a directory with some .JPG files:
FLS=: 0{"1 dir '*.jpg'
createThreads 5
MUTEX=: 10 T. 1 NB. Recursive mutex; either fails.
mtFileWork=: 3 : 0
tm=. 6!:1''
while. 0<#FLS do.
tn=. ":3 T. '' NB. Thread number as char
varnm=. ' '-.~'threadVar',tn
smoutput 'Thread ',tn,' locking at ',":qts''
11 T. y
smoutput 'Thread ',tn,' locked at ',":qts''
(varnm,' FLS')=: split FLS
smoutput 'Thread ',tn,' unlocking at ',(":qts''),' for file ',flnm=.
".varnm
13 T. y
smoutput 'Thread ',tn,' unlocked at ',":qts''
#read_image flnm NB. ¡Fails here!
end.
tm=. tm,~6!:1''
NB.EG mtFileWork t. '' MUTEX [ mtFileWork t. '' MUTEX [ mtFileWork t. ''
MUTEX [ mtFileWork t. '' MUTEX [ mtFileWork t. '' MUTEX
)
Any help is appreciated!
Thanks,
Devon
On Tue, May 10, 2022 at 4:46 PM Henry Rich <henryhr...@gmail.com> wrote:
If you can get me a version that fails on Windows I'll look at it.
Henry Rich
On 5/10/2022 4:20 PM, Devon McCormick wrote:
> Hi,
>
> Has anyone had success using the multi-threading mutex primitives? I've
> had limited success - I'll be presenting some basic routines at NYCJUG
this
> evening (18:00 EDT -
> https://www.meetup.com/J-Dynamic-Functional-Programming/) - but have
been
> unable to run multiple threads on a real-life process without crashing J.
>
> The following simplified demo seems to work OK but the version of this
> where I do actual work crashes - with "Process shell<1> exited abnormally
> with code 5" - after two to thirty repetitions.
>
> MUTEX=: 10 T. 0 NB. Fast mutex
> createThreads=: 3 : '{{ 0 T. '''' }} ^:y]'''''
> qts=: 6!:0
> createThreads 5
> GVAR=: 100?@$1e6 NB. Initialize global threads
will
> consume
>
> multiLockMsgUnlock=: 3 : 0
> while. 0<#GVAR do.
> tn=. ":3 T. '' NB. Thread number as char
> varnm=: ' '-.~'threadVar',tn
> smoutput 'Thread ',tn,' locking at ',":qts''
> 11 T. y
> smoutput 'Thread ',tn,' locked at ',":qts''
> (varnm,' GVAR')=: split GVAR
> smoutput 'Thread ',tn,' unlocking at ',(":qts''),' with
> ',tn,'=',":".varnm
> 13 T. y
> smoutput 'Thread ',tn,' unlocked at ',(":qts''),';
#GVAR=',":#GVAR
> end.
> )
> NB. Start five processes (one line):
> multiLockMsgUnlock t. '' MUTEX [ multiLockMsgUnlock t. '' MUTEX [
> multiLockMsgUnlock t. '' MUTEX [ multiLockMsgUnlock t. '' MUTEX [
> multiLockMsgUnlock t. '' MUTEX
>
> The actual work I'm doing is on files, a list of whose names corresponds
to
> the GVAR vector above.
>
> Any suggestions are welcome.
>
> Cheers,
>
> Devon
>
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