Exceeding the number of open files is an error, but it is most likely that managing them with the right kind of structure is the issue.

The way I usually do that is to use a stack just like in the old PDP-11 days. This ensures that files are opened and closed in a non-abusive way so that you can catch the abuse at the right point and may even solve the problem before it happens, just because you organised your recursive code better.

By the way, the hash-style subroutine parameters can be replaced with whatever you normally do, they are only there for clarity although if you do want to try that out too... don't forget to enclose the parameter array (@_) in brackets when reloading it into a hash or it won't work -- the point at which you can check the number of open files is marked in subroutine "Open"

my %controlCentre=();

$controlCentre{ FH } = [];
$controlCentre{ DH } = [];

Traverse( tree => 'whatever-path',
          control => \%controlCentre );

sub Traverse{
    my %par = (@_);
    my $dh = OpenDir(dir=>$par{ tree },
                     control=>$par{control});
    foreach my $file ( grep !/^\./, readdir $dh ) {
        my $path = "$par{tree}/$file";
        if ( -d $path ) {
            Traverse( tree => $path,
                      control => $par{ control }
                    );
        else {
            ProcessFile( name => $path,
                         control => $par{ control } );
        }
    }
    CloseDir( dh => $dh, control => $par{ control });
}

sub ProcessFile{ 
    my %par =(@_);
    my $fh = Open( cmd => "<$par{name}",
                   control =>$par{control} );
    # ...
    # process <$fh> here with any recursive calls
    # to ProcessFile that may be required
    #...

    Close( control => $par{ control } ),
           fh=>$fh );
}

sub Open{
    my %par = (@_);
    open my $fh, $par{ cmd };
    my $aref=$par{ control } -> { FH };
    push @$aref, $fh;

    # N.B. $#$aref is now one less than
    # the count of open files

    return $fh;
}

sub Close{
    my %par = (@_);
    close $par{ fh };
    my $aref = $par{ control } -> { FH };
    my $fh = pop @$aref;
    ( $fh eq $par{ fh } )
        or die "fh stack was abused: "
             . "$fh does not match $par{ fh }";
}

sub OpenDir{
    my %par = (@_);
    opendir my $dh, $par{ dir };
    my $aref=$par{ control } -> { DH };
    push @$aref, $dh;
    return $dh;
}

sub CloseDir
    my %par = (@_);
    closedir $par{ dh };
    my $aref = $par{ control } -> { DH };
    my $dh = pop @$aref;
    ( $dh eq $par{ dh } )
        or die "dh stack was abused: "
             . "$dh does not match $par{ dh }";
}
[download]

-S

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.