How to make parallel execution on folder ? Post: 302922775

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Top Forums Shell Programming and Scripting How to make parallel execution on folder ? Post 302922775 by drl on Tuesday 28th of October 2014 08:48:19 AM

10-28-2014

Registered User

Hi.

One technique for parallelizing processing on large files is to use GNU parallel. If you are interested in re-arranging the order of fields in a file, say with cut or awk, then parallel can create a sequence of processes to do this in chunks.

Here's an example from the man page:

Code:

EXAMPLE: Processing a big file using more cores
       To process a big file or some output you can use --pipe to split up the
       data into blocks and pipe the blocks into the processing program.

       If the program is gzip -9 you can do:

       cat bigfile | parallel --pipe --recend '' -k gzip -9 >bigfile.gz

       This will split bigfile into blocks of 1 MB and pass that to gzip -9 in
       parallel. One gzip will be run per CPU core. The output of gzip -9 will
       be kept in order and saved to bigfile.gz

       gzip works fine if the output is appended, but some processing does not
       work like that - for example sorting. For this GNU parallel can put the
       output of each command into a file. This will sort a big file in
       parallel:

       cat bigfile | parallel --pipe --files sort | parallel -Xj1 sort -m {}
       ';' rm {} >bigfile.sort

       Here bigfile is split into blocks of around 1MB, each block ending in
       '\n' (which is the default for --recend). Each block is passed to sort
       and the output from sort is saved into files. These files are passed to
       the second parallel that runs sort -m on the files before it removes
       the files. The output is saved to bigfile.sort.

Note that it covers two cases, the second being where the process cannot do simple appending.

Best wishes ... cheers, drl

drl

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LEARN ABOUT DEBIAN

parallel-scp

PARALLEL-SCP(1) 														   PARALLEL-SCP(1)

NAME

       parallel-scp - parallel versions of scp

SYNOPSIS

       parallel-scp [OPTIONS] -h hosts.txt local remote

DESCRIPTION

       pssh provides a number of commands for executing against a group of computers, using SSH. It's most useful for operating on clusters of
       homogenously-configured hosts.

       parallel-scp copy files in parallel to a set of machines.

OPTIONS

       -r --recursive
	   recusively copy directories (OPTIONAL)

       -h --hosts
	   hosts file (each line "host[:port] [user]")

       -l --user
	   username (OPTIONAL)

       -p --par
	   max number of parallel threads (OPTIONAL)

       -o --outdir
	   output directory for stdout files (OPTIONAL)

       -e --errdir
	   output directory for stderr files (OPTIONAL)

       -t --timeout
	   timeout (secs) (-1 = no timeout) per host (OPTIONAL)

       -O --options
	   SSH options (OPTIONAL)

       -v --verbose
	   turn on warning and diagnostic messages (OPTIONAL)

EXAMPLE

       The following example runs hostname on three machines (IPs or hostnames) specified in the file ips.txt using login irb2 and saves the
       output in /tmp/foo.

	   # parallel-scp -h ips.txt -l irb2 /etc/hosts /tmp/hosts
	   Success on 128.112.152.122:22
	   Success on 18.31.0.190:22
	   Success on 128.232.103.201:22

ENVIRONMENT

       All four programs take similar sets of options. All of these options can be set using the following environment variables:

       o   PSSH_HOSTS
       o   PSSH_USER
       o   PSSH_PAR
       o   PSSH_OUTDIR
       o   PSSH_VERBOSE
       o   PSSH_OPTIONS

SEE ALSO

       parallel-ssh(1), parallel-slurp(1), parallel-nuke(1), parallel-rsync(1), ssh(1), scp(1),

AUTHOR

       Brent N. Chun <bnc@theether.org>

COPYING

       Copyright: 2003, 2004, 2005, 2006, 2007 Brent N. Chun

NOTES

	1. bnc@theether.org
	   mailto:bnc@theether.org

								    03/30/2009							   PARALLEL-SCP(1)

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