in reply to Re: Opens but Won't Write to file
in thread Opens but Won't Write to file

Ignore select. The simplest way to turn off buffering on a handle is 
use IO::Handle qw( );
HANDLE->autoflush(1);

[download]

Replies are listed 'Best First'.
Re^3: Opens but Won't Write to file
by BrowserUk (Patriarch) on Oct 30, 2009 at 22:08 UTC

    Simplest, but costly. From the docs: 

     use IO::Handle;    # thousands of lines just for autoflush :-(

    [download]

    I think that comment originates from someone rather well respected within the perl community.

    That could be avoided by a simple (untested): 

    sub autoflush{ my $old = select $_[ 0 ]; $|=1; select $old; }

...
autoflush $fh;

    [download]
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]
[select]

      Actually, the OP already has IO::Handle loaded (via IO::Socket via IO::Socket::INET), so it's free for him.

      For others, it has a one-time cost of 100ms. 

      >perl -le"use Time::HiRes qw( time ); $stime=time; require IO::Handle;
+ $etime=time; print $etime-$stime;"
0.082003116607666

>perl -le"use Time::HiRes qw( time ); $stime=time; require IO::Handle;
+ $etime=time; print $etime-$stime;"
0.0974130630493164

>perl -le"use Time::HiRes qw( time ); $stime=time; require IO::Handle;
+ $etime=time; print $etime-$stime;"
0.120858192443848

      [download]

      It's up to them if that's acceptable or not. If it's not, I suggest copying autoflush out of IO::Handle and call it as follows rather than twiddling with select and $| directly. 

      autoflush(HANDLE, 1);

      [download]
[reply]
[d/l]
[select]
      Simplest, but costly.

      What kind of use do you have for a UDP server where the overhead of loading IO::Handle is even measurable?

[reply]

      Okay, thank you all for your kind notations. I have made a couple ssmall changes, doing the 'Standard' thing with Open OR Die and then using Select and autoflush($|=1); Thanks again to all Jim-

[reply]
Re^3: Opens but Won't Write to file
by MidLifeXis (Monsignor) on Nov 01, 2009 at 00:21 UTC

    Aaah, yes. Old habits (this is a monastery, after all) die hard. I guess I need to update that habit.

    --MidLifeXis

[reply]

In Section Seekers of Perl Wisdom