| dharana 2005-04-09, 7:45 am |
|
Barry Pearce wrote:
>
> Right but both flock (which is not used by the example above) and
> sempahores etc have serious imlpications for the operating system when
> you start looking at 10000 of them. Semaphores typically dont get
> cleaned up when the process dies - bad news - you have used o/s
> resource. file locks do. However, if you use a .lck file then
> technically you can support a million concurrently. By the time your
> system using flock/semaphores gets that far you have probably run out of
> memory on your server - so now I would be concerned about how long a
> session remained 'locked' for - otherwise it is easy to produce a DoS
> attack by simply starting up a large number of sessions in whatever the
> timeframe is...
>
One small question, as I don't think I understand this completely. In
the case of FileSession semaphores become used only with the lock calls
enabled, not without them, right? And in the worst case, if the locks
where there they would create a semaphore per session until the cleanup
function gets called and deletes them? Does it works likes this?
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