parallel/doc/FUTURE_IDEAS

== Change number of jobs while running ==

Read -j from file. If the file is changed when a job completes the
file is re-read and the new number of jobs computed. If the number is
lower than before currently running jobs will be allowed to finish but
new jobs will not be started.

== Bug ==

(echo ; echo abc ; echo abc; echo ; echo bbc) | parallel --colsep b -v echo {1}{2}

== SQL ==

Example with %0a as newline
sql :my_postgres?'\dt %0a SELECT * FROM users'

cat ~/.sql/aliases | parallel --colsep '\s' sql {1} '"select 0.14+3;" | grep -q 3.14 || (echo dead: {1}; exit 1)'

== FEX ==

fex syntax for splitting fields
http://www.semicomplete.com/projects/fex/
sql :foo 'select * from bar' | parallel --fex '|{1,2}' do_stuff {2} {1}


--autocolsep: Læs alle linjer.
Prøv fastlængde: Find tegn, som står i alle linjer på de samme pladser. Risiko for falske pos
Prøv fieldsep: Find eet tegn, som optræder det samme antal gange i alle linjer (tab sep)
Prøv klyngesep: Find den samme klynge tegn, som står samme antal gange i alle linjer (' | ' sep)
Fjern whitespace før og efter colonne

hvis der er n af tegn A og 2n af tegn B, så 

  a | b | c

Simpleste: tab sep

for hver linje
  max,min count for hver char

for hver char
  if max == min :
    potentiel
    min_potentiel = min(min_potentiel,min)

for potentiel:
  if min % min_potentiel = 0: sepchars += potentiel,no of sepchars += min / min_potentiel

colsep = [sepchars]{no_of_sepchars}


# Hvordan udregnes system limits på remote systems hvis jeg ikke ved, hvormange
# argumenter, der er? Lav system limits lokalt og lad det være max

# TODO max_line_length on remote
# TODO compute how many can be transferred within max_line_length
# TODO Unittest with filename that is long and requires a lot of quoting. Will there be to many
# TODO --max-number-of-jobs print the system limited number of jobs

# TODO Debian package

# TODO to kill from a run script parallel should set PARALLEL_PID that can be sig termed

=head1 YouTube video2

Converting of WAV files to MP3 using GNU Parallel

# Run one jobs per CPU core
# For 'foo.wav' call the output file 'foo.mp3'

find music-files -type f | parallel -j+0 lame {} -o {.}.mp3

# Run one jobs per CPU core
# Run on local computer + 2 remote computers
# Give us progress information
# For 'foo.wav' call the output file 'foo.mp3'

find music-files -type f | parallel -j+0 -S :,server1,server2 \
--eta --trc {.}.mp3 lame {} -o {.}.mp3

# Colsep
# sem
# --retry

(echo a1.txt; echo b1.txt; echo c1.txt; echo a2.txt; echo b2.txt; echo c2.txt;)| \
parallel -X -N 3 my-program --file={}

(echo a1.txt; echo b1.txt; echo c1.txt; echo d1.txt; echo e1.txt; echo f1.txt;)| \
parallel -X my-program --file={}

# First job controls the tty
# -u needed because output should not be saved for later

find . -type f | parallel -uXj1 vim
find . -type f | parallel -uXj1 emacs

# If you have 1000 files only one contains 'foobar'
# stop when this one is found

find . -type f | parallel  grep -l foobar | head -1


# To test a list of hosts are up and pingable save this
# to a file called machinesup

#!/usr/bin/parallel --shebang --no-run-if-empty ping -c 3 {} >/dev/null 2>&1

google.com
yahoo.com
nowhere.gone

# Then:
#   chmod 755 machinesup
#   ./machinesup || echo Some machines are down



=head1 YouTube video

GNU Parallel is a tool with lots of uses in shell. Every time you use
xargs or a for-loop GNU Parallel can probably do that faster, safer
and more readable.

If you have access to more computers through ssh, GNU Parallel makes
it easy to distribute jobs to these.

terminal2: ssh parallel@vh2.pi.dk
ssh parallel@vh2.pi.dk
 and  

PS1="\[\e[7m\]GNU Parallel:\[\033[01;34m\]\w\[\033[00m\e[27m\]$ "
gunzip logs/*gz
rm -f logs/*bz2*
rm -rf zip/*[^p]
rm -rf dirs/*
rm -rf parallel-*bz2

xvidcap
ffmpeg -i 20100616_002.mp4 -ab 320k -ar 44100 speak.mp3
# Merge video using youtube
#ffmpeg -i speak.mp3 -i xvidcap.mpeg -target mpeg -hq -minrate 8000000 \
#-title "GNU Parallel" -author "Ole Tange" -copyright "(CC-By-SA) 2010" -comment "Intro video of GNU Parallel 20100616" videoaudio.mpg

# GNU PARALLEL - BASIC USAGE
# A GNU tool for parallelizing shell commands

## Ole Tange Author

# GET GNU PARALLEL
wget ftp://ftp.gnu.org/gnu/parallel/parallel-20100620.tar.bz2
tar xjf parallel-20100620.tar.bz2
cd parallel-20100620
./configure && make   ##
su
make install
exit
cd

## scp /usr/local/bin/parallel root@parallel:/usr/local/bin/


# YOUR FIRST PARALLEL JOBS
cd logs
du
/usr/bin/time gzip -1 *
## 24 sek - 22 sek
/usr/bin/time gunzip *
## 24 sek - 18
ls | time parallel gzip -1
## 17 sek - 10
ls | time parallel gunzip
## 25 sek - 19

# RECOMPRESS gz TO bz2
ls | time parallel gzip -1
ls *.gz | time parallel -j+0 --eta 'zcat {} | bzip2 -9 >{.}.bz2'
## Explain command line
## vis top local
## Man that is boring
## 2m41s - 2m - 3m35s

# RECOMPRESS gz TO bz2 USING local(:) AND REMOTE server1-4
ls *.gz |time parallel -j+0 --eta -Sserver1,server2,server3,server4,: \
--transfer --return {.}.bz2 --cleanup 'zcat {} | bzip2 -9 > {.}.bz2'
## Explain command line
## Explain server config
## vis top local
## vis top remote1-3
## 49 sek

# RECOMPRESS gz TO bz2 USING A SCRIPT ON local AND REMOTE server1-2,4
# (imagine the script is way more complex)
cp ../recompress /tmp
cat /tmp/recompress
ls *.gz |time parallel -j+0 --progress -Sserver1,server2,server4,: \
--trc {.}.bz2 --basefile /tmp/recompress '/tmp/recompress {} {.}.bz2'


# MAKING SMALL SCRIPTS
cd ../zip
ls -l
ls *.zip | parallel 'mkdir {.} && cd {.} && unzip ../{}' ###
ls -l

# GROUP OUTPUT
traceroute debian.org
traceroute debian.org & traceroute freenetproject.org  ###
(echo debian.org; echo freenetproject.org) | parallel traceroute ###

# KEEP ORDER
(echo debian.org; echo freenetproject.org) | parallel -k traceroute ###

# RUN MANY JOBS. USE OUTPUT
# Find the number of hosts responding to ping
ping -c 1 178.63.11.1
ping -c 1 178.63.11.1 | grep '64 bytes'
seq 1 255 | parallel -j255 ping -c 1 178.63.11.{} 2>&1 \
| grep '64 bytes' | wc -l
seq 1 255 | parallel -j0 ping -c 1 178.63.11.{} 2>&1 \
| grep '64 bytes' | wc -l

# MULTIPLE ARGUMENTS
# make dir: test-(1-5000).dir
cd ../dirs
rm -rf *; sync
seq 1 10 | parallel echo mkdir test-{}.dir
seq 1 5000 | time parallel mkdir test-{}.dir
## 15 sek

rm -rf *; sync
seq 1 10 | parallel -X echo mkdir test-{}.dir
seq 1 5000 | time parallel -X mkdir test-{}.dir

# CALLING GNU PARALLEL FROM GNU PARALLEL
# make dir: top-(1-100)/sub-(1-100)
rm -rf *; sync
seq 1 100 | time parallel -I @@ \
'mkdir top-@@; seq 1 100 | parallel -X mkdir top-@@/sub-{}'
find | wc -l

cd
# Thank you for watching
#
# If you like GNU Parallel:
# * Post this video on your blog/Twitter/Facebook/Linkedin
# * Join the mailing list http://lists.gnu.org/mailman/listinfo/parallel
# * Request or write a review for your favourite magazine
# * Request or build a package for your favourite distribution
# * Invite me for your next conference (Contact http://ole.tange.dk)
#
# If GNU Parallel saves you money:
# * Donate to FSF https://my.fsf.org/donate/
#
# Find GNU Parallel at http://www.gnu.org/software/parallel/


# GIVE ME THE FIRST RESULT
(echo foss.org.my; echo debian.org; echo freenetproject.org) | parallel -H2 traceroute {}";false"

find . -type f | parallel -k -j150% -n 1000 -m grep -H -n STRING {}

(echo foss.org.my; echo debian.org; echo freenetproject.org) | parallel traceroute


=head1 IDEAS

Kan vi lave flere ssh'er, hvis vi venter lidt?
En ssh med 20% loss og 900 ms delay, så kan login nås på 15 sek.

Test if -0 works on filenames ending in '\n'

If there are nomore jobs (STDIN is eof) then make sure to
distribute the arguments evenly if running -X.


=head1 options

One char options not used: A D F G J K O Q R T Z


=head2 mutex

mutex -b -n -l lockid -m max_locks [command]
mutex -u lockid

-b run command in background 
-l lockfile will lock using the lockid
-n nonblocking
-m maximal number of locks (default 1)
-u unlock

If command given works like: mutex -l lockfile -n number_of_locks ; command; mutex -u lockfile
If -b given works like: mutex -l lockfile -n number_of_locks ; (command; mutex -u lockfile)&

Kan vi finde på lockid som giver mening?

Parallelize so this can be done:
mdm.screen find dir -execdir mdm-run cmd {} \;
Maybe:
find dir -execdir par$ --communication-file /tmp/comfile cmd {} \;

find dir -execdir mutex -j4 -b cmd {} \;

=head2 Comfile

This will put a lock on /tmp/comfile. The number of locks is the number of running commands.
If the number is smaller than -j then it will start a process in the background ( cmd & ),
otherwise wait.

par$ --wait /tmp/comfile will wait until no more locks on the file



=head1 Unlikely

Accept signal INT instead of TERM to complete current running jobs but
do not start new jobs. Print out the number of jobs waiting to
complete on STDERR. Accept sig INT again to kill now. This seems to be
hard, as all foreground processes get the INT from the shell.



# Gzip all files in parallel
parallel gzip ::: *

# Convert *.wav to *.mp3 using LAME running one process per CPU core:
parallel -j+0 lame {} -o {.}.mp3 ::: *.wav

# Make an uncompressed version of all *.gz
parallel zcat {} ">"{.} ::: *.gz

# Recompress all .gz files using bzip2 running 1 job per CPU core:
find . -name '*.gz' | parallel -j+0 "zcat {} | bzip2 >{.}.bz2 && rm {}"

# Create a directory for each zip-file and unzip it in that dir
parallel 'mkdir {.}; cd {.}; unzip ../{}' ::: *.zip

# Convert all *.mp3 in subdirs to *.ogg running 
#   one process per CPU core on local computer and server2
find . -name '*.mp3' | parallel --trc {.}.ogg -j+0 -S server2,: \
         'mpg321 -w - {} | oggenc -q0 - -o {.}.ogg'

# Run mycmd on column 1-3 of each row of TAB separated values
parallel -a table_file.tsv --colsep '\t' mycmd -o {2} {3} -i {1}

# Run traceroute in parallel, but keep the output order the same
parallel -k traceroute ::: foss.org.my debian.org freenetproject.org