Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask
 
PerlMonks  

comment on

( [id://3333] : superdoc . print w/replies, xml ) Need Help??
Since I store the PID value of the process in a database, this PID might be re-used by the operating system when deleting the record at startup.

There is no way to handle 100% of the termination cases at the time of termination no matter what you do (e.g. your machine suddenly loses power and the UPS fails), so you must have code that detects stale records at some future point in time. There are several ways of doing this. The canonical way to verify a pid is to record it in a lock file that the process keeps locked while it is running. When you verify the pid, if you can lock the file, the process has obviously died. Another more generic way could be to write a separate "checkpoint" record that you remove in your END block. If you start up and the checkpoint record exists, you remove the stale PID record the that checkpoint record points to as well as the checkpoint record.


In reply to Re^3: Signals and END block by bluto
in thread Signals and END block by Marcello

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



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.