Debug openings and closings

senduran has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Debug openings and closings by FunkyMonk (Bishop) on Aug 27, 2007 at 08:38 UTC
You can override CORE::open and close. The following should get you going: `BEGIN { CORE::GLOBAL::open = \&my_open; sub my_open(;$@) { my ( undef, $filename, $line ) = caller; print "opening $_[2] in $filename:$line\n"; CORE::open($_[0], $_[1], $_[2]); } } open my $fh, "<", "temp~" or die $!;` [download] Googling came up with Testing Legacy Code	[reply] [d/l] [select]
Re: Debug openings and closings by moritz (Cardinal) on Aug 27, 2007 at 08:26 UTC
On linux and unix based systems you can use the command (not perl function!) `strace` to watch which files are opened and closed. On windows you can use filemon for that. I know that's not exactly what you want, but maybe when you see which files are opened you can guess which module is to blame. Perl 6 in German -- Difficult Sudoku	[reply] [d/l]
Re^2: Debug openings and closings by Fletch (Bishop) on Aug 27, 2007 at 14:44 UTC
Actually on Linuxen it's `strace`, on Solaris (and other SysVs?) it's `truss` (as Anno mentions below), and on BSDen it's a pair of utilities `ktrace` and `kdump` (Free- and OS X for sure, pretty sure about Open-).</pedant>	[reply]
Re: Debug openings and closings by bruceb3 (Pilgrim) on Aug 27, 2007 at 09:11 UTC
As a suggestion to avoid this kind of problem, if you use a lexical variable as a file handle instead of a bareword, when the variable goes out of scope, Perl will automatically close the file for you. e.g. `open my $file, "<", $filename # use lexical variable open FILE, "<", $filename # use bareword.` [download] So if you have a subroutine; `sub foo { my ($filename) = @_; open my $file, "<", $filename or die "blah :$!\n"; while (<$file>) { # etc } # explicit call to close not needed. }` [download] The file will be closed at the end of the foo subroutine. If you want the file handle then return it. And if you aren't using a lot of subroutines but want this behavior, simply start a new block.	[reply] [d/l] [select]
Re: Debug openings and closings by BrowserUk (Patriarch) on Aug 27, 2007 at 08:46 UTC
Take a look at Fatal. 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. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply]
Re: Debug openings and closings by Anno (Deacon) on Aug 27, 2007 at 08:38 UTC
On most Unix systems you can trace system calls (that includes `open()` and `close()`) using something like `strace` (`truss` in other systems). Anno	[reply] [d/l] [select]
Re: Debug openings and closings by ides (Deacon) on Aug 27, 2007 at 14:10 UTC
Definitely find out why you're running out of file handles, but if you find at the end of the day it is necessary, you can up these limits on your Linux/Unix system. Googling around for ulimit and that error message should help you to find how to do that on your particular OS. Frank Wiles <frank@revsys.com> www.revsys.com	[reply]