Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

Best way to control multiple threads writing & reading from the same file (Perl)

Posted on 2010-11-27
1
Medium Priority
?
249 Views
Last Modified: 2012-05-10
Expertos,

What's the best way to control multiple threads writing & reading from the same file in Perl?

I'm working with the threads::simple module.

Thanks!

0
Comment
Question by:php-newbie
1 Comment
 
LVL 16

Accepted Solution

by:
Justin Mathews earned 2000 total points
ID: 34230935
You can use flock() to lock a file handle in exclusive or shared mode. So each thread can call flock() to acquire an exclusive lock before writing to the file and immediately release the lock so that other threads also can obtain a lock and write to the file. Here is the sample from the documentation (http://perldoc.perl.org/functions/flock.html):



use Fcntl ':flock'; # import LOCK_* constants

sub lock {
    flock(MBOX,LOCK_EX);
    # and, in case someone appended
    # while we were waiting...
    seek(MBOX, 0, 2);
}

sub unlock {
    flock(MBOX,LOCK_UN);
}

open(MBOX, ">>/usr/spool/mail/$ENV{'USER'}")
        or die "Can't open mailbox: $!";

lock();
print MBOX $msg,"\n\n";
unlock();

Open in new window

0

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

On Microsoft Windows, if  when you click or type the name of a .pl file, you get an error "is not recognized as an internal or external command, operable program or batch file", then this means you do not have the .pl file extension associated with …
I have been pestered over the years to produce and distribute regular data extracts, and often the request have explicitly requested the data be emailed as an Excel attachement; specifically Excel, as it appears: CSV files confuse (no Red or Green h…
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…
Six Sigma Control Plans

916 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question