From @AlexDaniel

Code​:

sub get-output() {
  my $proc = Proc​::Async.new​: :w, â��headâ��, â��-nâ��, â��1â��;
  my $success;
  react {
  whenever $proc.stdout { $success = True }
  whenever $proc.start { die â��FAIL!â�� unless $success }

  $proc.print​: â��one\ntwo\nthree\nfourâ��;
  $proc.close-stdin;
  }
  say $++;
}

loop { get-output }

Again, the result depends on your luck. Ideally it should not �die� ever, because there should always be one line in the output and therefore $success will be set to true. However, sometimes its stdout is empty and therefore it fails. It may fail after 20+ executions, and sometimes it fails almost immediately.

Related ticket​: https://rt-archive.perl.org/perl6/Ticket/Display.html?id=131763

From @niner

$proc.print is asynchronous while $proc.close-stdin is not. In some cases $proc simply does not get the input because we closed its stdin before printing anything.

If .close-stdin is meant to by synchronous, this needs a doc patch. Otherwise we'd probably need to await any outstanding write promises before performing the actual nqp​::closefh.

The RT System itself - Status changed from 'new' to 'open'

From @AlexDaniel

Alright, it seems that rakudo is not entirely incorrect here. See this discussion​: https://irclog.perlgeek.de/perl6-dev/2017-07-18#i_14885863

TL;DR, one should use something like this​:

whenever $proc.print(“one\ntwo\nthree\nfour”) { $proc.close-stdin }

So it seems that it's not a bug, but a trap maybe?

I'll leave this for somebody else to close.

On 2017-07-17 22​:45​:01, alex.jakimenko@​gmail.com wrote​:

Code​:

sub get-output() {
my $proc = Proc​::Async.new​: :w, ‘head’, ‘-n’, ‘1’;
my $success;
react {
whenever $proc.stdout { $success = True }
whenever $proc.start { die ‘FAIL!’ unless $success }

$proc.print​: “one\ntwo\nthree\nfour”;
$proc.close-stdin;
}
say $++;
}

loop { get-output }

Again, the result depends on your luck. Ideally it should not “die”
ever, because there should always be one line in the output and
therefore $success will be set to true. However, sometimes its stdout
is empty and therefore it fails. It may fail after 20+ executions, and
sometimes it fails almost immediately.

Related ticket​: https://rt-archive.perl.org/perl6/Ticket/Display.html?id=131763

From @AlexDaniel

Closing this myself in favor of this ticket​: Raku/doc#1567

On 2017-07-17 23​:51​:21, alex.jakimenko@​gmail.com wrote​:

Alright, it seems that rakudo is not entirely incorrect here. See this
discussion​: https://irclog.perlgeek.de/perl6-dev/2017-07-18#i_14885863

TL;DR, one should use something like this​:

whenever $proc.print(“one\ntwo\nthree\nfour”) { $proc.close-stdin }

So it seems that it's not a bug, but a trap maybe?

I'll leave this for somebody else to close.

On 2017-07-17 22​:45​:01, alex.jakimenko@​gmail.com wrote​:

Code​:

sub get-output() {
my $proc = Proc​::Async.new​: :w, ‘head’, ‘-n’, ‘1’;
my $success;
react {
whenever $proc.stdout { $success = True }
whenever $proc.start { die ‘FAIL!’ unless $success }

$proc.print​: “one\ntwo\nthree\nfour”;
$proc.close-stdin;
}
say $++;
}

loop { get-output }

Again, the result depends on your luck. Ideally it should not “die”
ever, because there should always be one line in the output and
therefore $success will be set to true. However, sometimes its stdout
is empty and therefore it fails. It may fail after 20+ executions, and
sometimes it fails almost immediately.

Related ticket​: https://rt-archive.perl.org/perl6/Ticket/Display.html?id=131763

@AlexDaniel - Status changed from 'open' to 'resolved'