parallel: --line-buffer memory usage changed from 2x to 1x.

doc/haikus

@@ -2,10 +2,6 @@ Quote of the month:
 
 
 
-With GNU Parallel you sure can!
-I like getting things done
-
---Kyle Lady @kylelady@twitter
 
 
 
@@ -37,7 +33,12 @@ It's the MapReduce of our generation!
 
 
 === Used ===
-  Ok! GNU Parallel is one of the best things out there. Almost as good as vanilla ice cream.
+With GNU Parallel you sure can!
+I like getting things done
+
+--Kyle Lady @kylelady@twitter
+
+Ok! GNU Parallel is one of the best things out there. Almost as good as vanilla ice cream.
     -- @coffe@mastodon.art
 
 HOLY STUFF I LOVE GNU PARALLEL

src/niceload

@@ -23,7 +23,7 @@
 use strict;
 use Getopt::Long;
 $Global::progname="niceload";
-$Global::version = 20190222;
+$Global::version = 20190223;
 Getopt::Long::Configure("bundling","require_order");
 get_options_from_array(\@ARGV) || die_usage();
 if($opt::version) {

src/parallel

@@ -200,13 +200,10 @@ sub pipe_tee_setup() {
 sub parcat_script() {
     # TODO if script fails: Use parallel -j0 --plain --lb cat ::: fifos
     my $script = q'{
-	use Symbol qw(gensym);
-	use IPC::Open3;
 	use POSIX qw(:errno_h);
 	use IO::Select;
 	use strict;
 	use threads;
-	use threads::shared;
 	use Thread::Queue;
 	use Fcntl qw(:DEFAULT :flock);
 
@@ -369,7 +366,7 @@ sub parcat_script() {
 	    fcntl($fh, &F_SETFL, $flags) || die $!; # Set the flags on the filehandle
 	}
     }';
-    return ::spacefree(1, $script);
+    return ::spacefree(3, $script);
 }
 
 sub sharder_script() {
@@ -432,7 +429,7 @@ sub pipe_shard_setup() {
 	open STDOUT, ">","/dev/null";
 	# The PERL_HASH_SEED must be the same for all sharders
 	# so B::hash will return the same value for any given input
-	$ENV{PERL_HASH_SEED} = $$;
+	$ENV{'PERL_HASH_SEED'} = $$;
 	exec qw(parallel --block 100k -q --pipe -j), $njobs,
 	    qw(--roundrobin -u perl -e), $script, ($opt::colsep || ","),
 	    $opt::shard, '{}', (map { (':::+', @{$_}) } @parcatfifos);
@@ -1698,7 +1695,7 @@ sub check_invalid_option_combinations() {
 
 sub init_globals() {
     # Defaults:
-    $Global::version = 20190222;
+    $Global::version = 20190223;
     $Global::progname = 'parallel';
     $Global::infinity = 2**31;
     $Global::debug = 0;
@@ -5054,6 +5051,10 @@ sub spacefree($$) {
 	# Keep newlines
 	$s =~ s/\n\n+/\n/sg;
 	$s =~ s/[ \t]+/ /mg;
+    } elsif(3 == $spaces) {
+	# Keep perl code required space
+	$s =~ s{([^a-zA-Z0-9/])\s+}{$1}sg;
+	$s =~ s{([a-zA-Z0-9/])\s+([^:a-zA-Z0-9/])}{$1$2}sg;
     } else {
 	$s =~ s/\s//mg;
     }
@@ -8516,7 +8517,7 @@ sub sshlogin_wrap($) {
 	} else {
 	    $bashfuncset = '$bashfunc = "";'
 	}
-	if($ENV{"parallel_bash_environment"}) {
+	if($ENV{'parallel_bash_environment'}) {
 	    $bashfuncset .= '$bashfunc .= "eval\ \"\$parallel_bash_environment\"\;";';
 	}
 	::debug("base64",$envset,$bashfuncset,"\n");
@@ -9527,7 +9528,11 @@ sub print_linebuffer($) {
 		# read remaining
 		my $halfline_ref = $self->{'halfline'}{$fdno};
 		if(grep /./, @$halfline_ref) {
-		    $self->add_returnsize(length join("",@$halfline_ref));
+		    my $returnsize = 0;
+		    for(@{$self->{'halfline'}{$fdno}}) {
+			$returnsize += length $_;
+		    }
+		    $self->add_returnsize($returnsize);
 		    if($opt::tag or defined $opt::tagstring) {
 			# Prepend $tag the the remaining half line
 			unshift @$halfline_ref, $self->tag();

src/parallel.pod

@@ -2148,7 +2148,7 @@ E.g.
 B<--shebang-wrap> must be set as the first option.
 
 
-=item B<--shellquote> (alpha testing)
+=item B<--shellquote> (beta testing)
 
 Does not run the command but quotes it. Useful for making quoted
 composed commands for GNU B<parallel>.

src/parallel_alternatives.pod

@@ -1959,6 +1959,46 @@ https://github.com/codingo/Interlace can be run with GNU B<parallel>:
 
 https://github.com/codingo/Interlace (Last checked: 2019-02)
 
+
+=head2 DIFFERENCES BETWEEN otonvm Parallel AND GNU Parallel
+
+I have been unable to get the code to run at all. It seems unfinished.
+
+https://github.com/otonvm/Parallel (Last checked: 2019-02)
+
+
+=head2 DIFFERENCES BETWEEN k-bx par AND GNU Parallel
+
+B<par> requires Haskell to work. This limits the number of platforms
+this can work on.
+
+B<par> does line buffering in memory. The memory usage is 3x the
+longest line (compared to 1x for B<parallel --lb>). Commands must be
+given as arguments. There is no template.
+
+These are the examples from https://github.com/k-bx/par with the
+corresponding GNU B<parallel> command.
+
+  par "echo foo; sleep 1; echo foo; sleep 1; echo foo" \
+      "echo bar; sleep 1; echo bar; sleep 1; echo bar" && echo "success"
+  parallel --lb ::: "echo foo; sleep 1; echo foo; sleep 1; echo foo" \
+      "echo bar; sleep 1; echo bar; sleep 1; echo bar" && echo "success"
+
+  par "echo foo; sleep 1; foofoo" \
+      "echo bar; sleep 1; echo bar; sleep 1; echo bar" && echo "success"
+  parallel --lb --halt 1 ::: "echo foo; sleep 1; foofoo" \
+      "echo bar; sleep 1; echo bar; sleep 1; echo bar" && echo "success"
+
+  par "PARPREFIX=[fooechoer] echo foo" "PARPREFIX=[bar] echo bar"
+  parallel --lb --colsep , --tagstring {1} {2} \
+    ::: "[fooechoer],echo foo" "[bar],echo bar"
+
+  par --succeed "foo" "bar" && echo 'wow'
+  parallel "foo" "bar"; true && echo 'wow'
+
+https://github.com/k-bx/par (Last checked: 2019-02)
+
+
 =head2 Todo
 
 Url for spread
@@ -1979,13 +2019,6 @@ https://github.com/xuchenCN/go-pssh
 
 https://github.com/amritb/with-this.git
 
-https://github.com/fd0/machma Requires Go >= 1.7.
-
-https://github.com/k-bx/par requires Haskell to work. This limits the
-number of platforms this can work on.
-
-https://github.com/otonvm/Parallel
-
 https://github.com/flesler/parallel
 
 https://github.com/Julian/Verge

src/parallel_design.pod

@@ -20,6 +20,14 @@ a single file: No need to mess around with environment variables like
 PERL5LIB.
 
 
+=head2 Interpreted language
+
+GNU B<parallel> is designed to be able to run on old systems. That
+means that it cannot depend on a compiler being installed - and
+especially not a compiler for a language that is younger than 20 years
+old.
+
+
 =head2 Old Perl style 
 
 GNU B<parallel> uses some old, deprecated constructs. This is due to a
@@ -526,6 +534,63 @@ The real killer comes when you try to combine several of these: Doing
 that correctly for all corner cases is next to impossible to do by
 hand.
 
+=head2 --shard
+
+The simple way to implement sharding would be to:
+
+=over 5
+
+=item 1
+
+start n jobs,
+
+=item 2
+
+split each line into columns,
+
+=item 3
+
+select the data from the relevant column
+
+=item 4
+
+compute a hash value from the data
+
+=item 5
+
+take the modulo n of the hash value
+
+=item 6
+
+pass the full line to the jobslot that has the computed value
+
+=back
+
+Unfortunately Perl is rather slow at computing the hash value (and
+somewhat slow at splitting into columns).
+
+One solution is to use a compiled language for the splitting and
+hashing, but that would go against the design criteria of not
+depending on a compiler.
+
+Luckily those tasks can be parallelized. So GNU B<parallel> starts n
+sharders that do step 2-6, and passes blocks of 100k to each of those
+in a round robin manner. To make sure these sharders compute the hash
+the same way, $PERL_HASH_SEED is set to the same value for all sharders.
+
+Running n sharders poses a new problem: Instead of having n outputs
+(one for each computed value) you now have n outputs for each of the n
+values, so in total n*n outputs; and you need to merge these n*n
+outputs together into n outputs.
+
+This can be done by simply running 'parallel -j0 --lb cat :::
+outputs_for_one_value', but that is rather inefficient, as it spawns a
+process for each file. Instead the core code from 'parcat' is run,
+which is also a bit faster.
+
+All the sharders and parcats communicate through named pipes that are
+unlinked as soon as they are opened.
+
 
 =head2 Shell shock
 

src/sql

@@ -574,7 +574,7 @@ $Global::Initfile && unlink $Global::Initfile;
 exit ($err);
 
 sub parse_options {
-    $Global::version = 20190222;
+    $Global::version = 20190223;
     $Global::progname = 'sql';
 
     # This must be done first as this may exec myself

testsuite/tests-to-run/parallel-local-3s.sh

@@ -275,6 +275,27 @@ par_test_diff_roundrobin_k() {
     fi
 }
 
+par_lb_mem_usage() {
+    long_line() {
+	perl -e 'print "x"x100_000_000'
+    }
+    export -f long_line
+    memusage() {
+	round=$1
+	shift
+	/usr/bin/time -v "$@" 2>&1 >/dev/null |
+	    perl -ne '/Maximum resident set size .kbytes.: (\d+)/ and print $1,"\n"' |
+	    perl -pe '$_ = int($_/'$round')."\n"'
+    }
+    # 1 line - RAM usage 1 x 100 MB
+    memusage 100000 parallel --lb ::: long_line
+    # 2 lines - RAM usage 1 x 100 MB
+    memusage 100000 parallel --lb ::: 'long_line; echo; long_line'
+    # 1 double length line - RAM usage 2 x 100 MB
+    memusage 100000 parallel --lb ::: 'long_line; long_line'
+}
+
+
 export -f $(compgen -A function | grep par_)
 compgen -A function | grep par_ | LC_ALL=C sort |
     parallel -j6 --tag -k --joblog /tmp/jl-`basename $0` '{} 2>&1'

testsuite/wanted-results/parallel-local-10s

@@ -27,8 +27,8 @@ par_interactive	sleep 0.1; echo opt-p 2 ?...n
 par_interactive	sleep 0.1; echo opt-p 3 ?...y
 par_interactive	spawn /tmp/parallel-script-for-expect
 par_k	### Test -k
-par_k	parallel: Warning: Only enough file handles to run 8 jobs in parallel.
-par_k	parallel: Warning: Running 'parallel -j0 -N 8 --pipe parallel -j0' or
+par_k	parallel: Warning: Only enough file handles to run 9 jobs in parallel.
+par_k	parallel: Warning: Running 'parallel -j0 -N 9 --pipe parallel -j0' or
 par_k	parallel: Warning: raising 'ulimit -n' or 'nofile' in /etc/security/limits.conf
 par_k	parallel: Warning: or /proc/sys/fs/file-max may help.
 par_k	begin

testsuite/wanted-results/parallel-local-3s

@@ -62,6 +62,9 @@ par_kill_term_twice	parallel: bash -c 'sleep 120 & pid=$!; wait $pid' 1
 par_kill_term_twice	bash-+-perl---bash---sleep
 par_kill_term_twice	     `-pstree
 par_kill_term_twice	bash---pstree
+par_lb_mem_usage	1
+par_lb_mem_usage	1
+par_lb_mem_usage	2
 par_multiline_commands	bug #50781: joblog format with multiline commands
 par_multiline_commands	1
 par_multiline_commands	finish 1

testsuite/wanted-results/parallel-local23

@@ -61,7 +61,7 @@ echo '### Check that 4 processes are really used'
 echo '### --version must have higher priority than retired options'
 ### --version must have higher priority than retired options
   $NICEPAR --version -g -Y -U -W -T | tail
-GNU parallel 20190123
+GNU parallel 20190223
 Copyright (C) 2007-2019 Ole Tange and Free Software Foundation, Inc.
 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
 This is free software: you are free to change and redistribute it.