Fixed bug #50081: --keep-order --round-robin should give predictable results.

src/parallel

@@ -597,24 +597,38 @@ sub nindex {
 		push @robin_queue, (sort { $a->seq() <=> $b->seq() }
 				    values %Global::running);
 	    }
-	    do {
-		$written = 0;
+	    if($opt::keeporder) {
 		for my $job (@robin_queue) {
 		    if($job->block_length() > 0) {
 			$written += $job->non_blocking_write();
 		    } else {
-			$job->set_block($header_ref,$buffer_ref,
-					$endpos,$recstart,$recend);
+			$job->set_block($header_ref,$buffer_ref,$endpos,$recstart,$recend);
 			$block_passed = 1;
 			$job->set_virgin(0);
 			$written += $job->non_blocking_write();
 			last;
 		    }
 		}
-		if($written) {
-		    $sleep = $sleep/1.5+0.001;
-		}
-	    } while($written and not $block_passed);
+	    } else {
+		do {
+		    $written = 0;
+		    for my $job (@robin_queue) {
+			if($job->block_length() > 0) {
+			    $written += $job->non_blocking_write();
+			} else {
+			    $job->set_block($header_ref,$buffer_ref,
+					    $endpos,$recstart,$recend);
+			    $block_passed = 1;
+			    $job->set_virgin(0);
+			    $written += $job->non_blocking_write();
+			    last;
+			}
+		    }
+		    if($written) {
+			$sleep = $sleep/1.5+0.001;
+		    }
+		} while($written and not $block_passed);
+	    }
 	    $sleep = ::reap_usleep($sleep);
 	}
 	return $written;
@@ -961,6 +975,7 @@ sub options_hash {
 	 "cat" => \$opt::cat,
 	 "fifo" => \$opt::fifo,
 	 "pipepart|pipe-part" => \$opt::pipepart,
+	 "tee" => \$opt::tee,
 	 "hgrp|hostgrp|hostgroup|hostgroups" => \$opt::hostgroups,
 	);
 }
@@ -7876,7 +7891,8 @@ sub start {
     if($opt::pipe) {
 	my ($stdin_fh) = ::gensym();
 	$pid = open3_setpgrp($stdin_fh,$stdout_fh,$stderr_fh,$command);
-	if($opt::roundrobin) {
+	if($opt::roundrobin and not $opt::keeporder) {
+	    # --keep-order will make sure the order will be reproducible
 	    ::set_fh_non_blocking($stdin_fh);
 	}
 	$job->set_fh(0,"w",$stdin_fh);

src/parallel.pod

@@ -988,6 +988,9 @@ to see the difference:
 If used with B<--onall> or B<--nonall> the output will grouped by
 sshlogin in sorted order.
 
+If used with B<--pipe --roundrobin> and the same input, the jobslots
+will get the same blocks in the same order in every run.
+
 
 =item B<-L> I<max-lines>
 

testsuite/tests-to-run/parallel-local-1s.sh

@@ -196,6 +196,7 @@ par_result_replace() {
     rm -rf /tmp/par_*_49983-*
 }
 
+
 export -f $(compgen -A function | grep par_)
 compgen -A function | grep par_ | sort |
     parallel -j6 --tag -k --joblog +/tmp/jl-`basename $0` '{} 2>&1'

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

@@ -79,6 +79,31 @@ par_pipepart_block() {
     rm /run/shm/parallel$$
 }
 
+par_keeporder_roundrobin() {
+    echo 'bug #50081: --keep-order --round-robin should give predictable results'
+
+    export PARALLEL="-j13 --block 1m --pipe --roundrobin"
+    random500m() {
+	< /dev/zero openssl enc -aes-128-ctr -K 1234 -iv 1234 2>/dev/null |
+	    head -c 500m;
+    }
+    a=$(random500m | parallel -k 'echo {#} $(md5sum)' | sort)
+    b=$(random500m | parallel -k 'echo {#} $(md5sum)' | sort)
+    c=$(random500m | parallel    'echo {#} $(md5sum)' | sort)
+    if [ "$a" == "$b" ] ; then
+	# Good: -k should be == -k
+	if [ "$a" == "$c" ] ; then
+	    # Bad: without -k the command should give different output
+	    echo 'Broken: a == c'
+	    printf "$a\n$b\n$c\n"
+	else
+	    echo OK
+	fi
+    else
+	echo 'Broken: a <> b'
+	printf "$a\n$b\n$c\n"
+    fi
+}
 
 export -f $(compgen -A function | grep par_)
 compgen -A function | grep par_ | sort | parallel -j6 --tag -k '{} 2>&1'

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

@@ -4,6 +4,8 @@ par_children_receive_sig	Got TERM
 par_children_receive_sig	Got TERM
 par_children_receive_sig	Got INT
 par_children_receive_sig	Got TERM
+par_keeporder_roundrobin	bug #50081: --keep-order --round-robin should give predictable results
+par_keeporder_roundrobin	OK
 par_kill_int_twice	### Are children killed if GNU Parallel receives INT twice? There should be no sleep at the end
 par_kill_int_twice	bash-+-perl---bash---sleep
 par_kill_int_twice	     `-pstree