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Jeremy Cline |
cce01a3 |
#!/bin/sh
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Jeremy Cline |
cce01a3 |
# Reads filenames on stdin, xz-compresses each in place.
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Jeremy Cline |
cce01a3 |
# Not optimal for "compress relatively few, large files" scenario!
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Jeremy Cline |
cce01a3 |
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Jeremy Cline |
cce01a3 |
# How many xz's to run in parallel:
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Jeremy Cline |
cce01a3 |
procgroup=""
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Jeremy Cline |
cce01a3 |
while test "$#" != 0; do
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Jeremy Cline |
cce01a3 |
# Get it from -jNUM
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Jeremy Cline |
cce01a3 |
N="${1#-j}"
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Jeremy Cline |
cce01a3 |
if test "$N" = "$1"; then
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Jeremy Cline |
cce01a3 |
# Not -j<something> - warn and ignore
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Jeremy Cline |
cce01a3 |
echo "parallel_xz: warning: unrecognized argument: '$1'"
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Jeremy Cline |
cce01a3 |
else
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Jeremy Cline |
cce01a3 |
procgroup="$N"
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Jeremy Cline |
cce01a3 |
fi
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Jeremy Cline |
cce01a3 |
shift
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Jeremy Cline |
cce01a3 |
done
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Jeremy Cline |
cce01a3 |
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Jeremy Cline |
cce01a3 |
# If told to use only one cpu:
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Jeremy Cline |
cce01a3 |
test "$procgroup" || exec xargs -r xz
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Jeremy Cline |
cce01a3 |
test "$procgroup" = 1 && exec xargs -r xz
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Jeremy Cline |
cce01a3 |
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Jeremy Cline |
cce01a3 |
# xz has some startup cost. If files are really small,
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Jeremy Cline |
cce01a3 |
# this cost might be significant. To combat this,
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Jeremy Cline |
cce01a3 |
# process several files (in sequence) by each xz process via -n 16:
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Jeremy Cline |
cce01a3 |
exec xargs -r -n 16 -P $procgroup xz
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