Spake Mike Branda on Wednesday, January 03, 2007 at 02:08PM -0500:
> So I've been playing with ImageMagick to batch process psd files into
> flattened jpgs. I have a bash script that runs a for loop with
> "convert" on a directory. What I have noticed is that in xosview on my
> Dual Intel Hyper Threaded box ( shows up as 4 cpu's cause of the HT ),
> only one ( or one half? ) CPU is doing all the work. Makes sense
> because of the whole user space kernel space thing and I don't really
> need both CPU's working on pieces of the same image anyway.
>
> What I would like though is a way to fork multiple children in the loop
> to start additional instances of convert until 4 are active. Then wait
> until one exits and then start on the next image. 4 active converts
> always until all the images are processed.
>
> i.e.
>
> mbranda:~> pstree
>
> ├─kdeinit─┬
> │ ├─konsole───bash───image_resize.sh─┬─convert
> |─convert
> |─convert
> |─convert
>
>
> Right now I just create 4 different dirs and run 4 instances of the
> shell script ( which calls convert ) on them. This makes the batching
> of a few hundred images go much faster. I know there's got to be a way
> to fork more instances and count how many are active. I figure the for
> loop will have to be smart in some way to fork and move on to the next
> image in $dir until the max of 4 instances is reached.
>
I don't do much shell scripting, but prepending '&' to the end of a sh
command is a fork.
Though the best way to do this would probably be using make...
hmm...
--
"You could be sad, but I'd rather you not be.
Don't dwell on the negative, just the positivity"
-- David "Ziggy" Marley, "Beautiful Day" (song)
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