Parallelism a la make -j <n> / GNU parallel

[Colin McEwan]

Hi there,

I don't know if this is anything that has ever been discussed or
considered, but would be interested in any thoughts.

I frequently find myself these days writing shell scripts, to run on
multi-core machines, which could easily exploit lots of parallelism (eg. a
batch of a hundred independent simulations).

The basic parallelism construct of '&' for async execution is highly
expressive, but it's not useful for this sort of use-case: starting up 100
jobs at once will leave them competing, and lead to excessive context
switching and paging.

So for practical purposes, I find myself reaching for 'make -j<n>' or GNU
parallel, both of which destroy the expressiveness of the shell script as I
have to redirect commands and parameters to Makefiles or stdout, and
wrestle with appropriate levels of quoting.

What I would really *like* would be an extension to the shell which
implements the same sort of parallelism-limiting / 'process pooling' found
in make or 'parallel' via an operator in the shell language, similar to '&'
which has semantics of *possibly* continuing asynchronously (like '&') if
system resources allow, or waiting for the process to complete (';').

Any thoughts, anyone?

Thanks!

-- 
C.

https://plus.google.com/109211294311109803299
https://www.facebook.com/mcewanca