Beefy Boxes and Bandwidth Generously Provided by pair Networks
We don't bite newbies here... much
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??
I have a program, where several instances run concurrently. They platforms to be supported are: Windows XP, Windows 2003 Server, Windows 2008 Server, and Windows 7 (64 Bit).

These processes 'share' a piece of code which should be executed as a critical region, i.e. only one of the processes is supposed to execute this part of the code at any time. To implement this, I use flock on a lockfile to guard entry and exit to the critical region, i.e. I basically do a

sysopen(LOCKFILE,$lockfile,O_WRONLY|O_CREAT); while(!flock(LOCKFILE, LOCK_EX|LOCK_NB)) { sleep($some_random_time); } ######################### # CRITICAL REGION IS HERE ######################### flock(LOCKFILE, LOCK_UN); close(LOCKFILE);
This works well. Now I wonder: Could there be cases, where a process gets killed while being in the critical region, BUT the lock is not being released (and therefore all other processes would be locked out forever)?

I wrote a small test program to research this case, but no matter how I killed the process holding the lock, the lock was always freed afterwards. Of course this doesn't mean that what I'm doing is safe. It just means that I was not able to break it.

Could someone with good experience in Windows programming give me some enlightment here?
-- 
Ronald Fischer <ynnor@mm.st>

In reply to flock on Windows : process killed while in critical region by rovf

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • 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! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, 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, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            For:     Use:
    & &amp;
    < &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.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others browsing the Monastery: (10)
    As of 2014-09-02 13:14 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      My favorite cookbook is:










      Results (22 votes), past polls