Parallel Each in j

peach.ijs

NB. parallel each: peach

NB. https://code.jsoftware.com/wiki/NYCJUG/2022-11-08#Work_with_Multi-threading

echo 'Must be at least running J904'
echo JLIB

nproc =: {{ {. 8 T. '' }}
createThreads=: 3 : '{{ 0 T. '''' }} ^:({. 8 T. '''')]'''''

peach =: 1 : 'u t. '''' y'
NB. Or even simpler:
peach =: t. ''

0 : 0
Usage:
First create some background worker threads, 1 per core:
   createThreads ''

Run 5 shell commands in parallel.

   NB. a is a list of strings to execute.
   a=. '; date +%s',"1~ 'sleep ' ,"1 ":"0 i.5
   a
sleep 0; date +%s
sleep 1; date +%s
sleep 2; date +%s
sleep 3; date +%s
sleep 4; date +%s
   
   NB. Execute (2!:0) on each string of a in parallel.
   r =. 2!:0 peach"1 a
   $r
5
   r
┌───────────┬───────────┬───────────┬───────────┬───────────┐
│1667991735 │1667991740 │1667991742 │1667991745 │1667991739 │
└───────────┴───────────┴───────────┴───────────┴───────────┘

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