[perl #131764] Passing stdin to Proc::Async mostly does not work ($proc.print: …; $proc.close-stdin)
Closing this myself in favor of this ticket:
https://github.com/perl6/doc/issues/1567
On 2017-07-17 23:51:21, alex.jakime...@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.jakime...@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 $success will be set to true. However, sometimes its stdout
> > is empty and therefore it fails. It may fail after 20+ executions, and
> > sometimes it fails almost immediately.
> >
> > Related ticket: https://rt.perl.org/Ticket/Display.html?id=131763
[perl #131764] Passing stdin to Proc::Async mostly does not work ($proc.print: …; $proc.close-stdin)
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.jakime...@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 $success will be set to true. However, sometimes its stdout
> is empty and therefore it fails. It may fail after 20+ executions, and
> sometimes it fails almost immediately.
>
> Related ticket: https://rt.perl.org/Ticket/Display.html?id=131763
[perl #131764] Passing stdin to Proc::Async mostly does not work ($proc.print: …; $proc.close-stdin)
$proc.print is asynchronous while $proc.close-stdin is not. In some cases $proc simply does not get the input because we closed its stdin before printing anything. If .close-stdin is meant to by synchronous, this needs a doc patch. Otherwise we'd probably need to await any outstanding write promises before performing the actual nqp::closefh.
[perl #131764] Passing stdin to Proc::Async mostly does not work ($proc.print: …; $proc.close-stdin)
# New Ticket Created by Aleks-Daniel Jakimenko-Aleksejev
# Please include the string: [perl #131764]
# in the subject line of all future correspondence about this issue.
# https://rt.perl.org/Ticket/Display.html?id=131764 >
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.perl.org/Ticket/Display.html?id=131763
