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Re^2: Timeouts: Any alternative to alarm in Win32?

by jbbarnes (Novice)
on Dec 04, 2008 at 00:11 UTC ( #727836=note: print w/replies, xml ) Need Help??


in reply to Re: Timeouts: Any alternative to alarm in Win32?
in thread Timeouts: Any alternative to alarm in Win32?

So far, this seems to work very well under Win32. I will test it under Linux when I get back to my office. Thanks a lot.

One question: Do you see any problem with removing the sleep 1; line from the loop? This code will be part of a loop itself to test the response of about 150 machines. I can normally get responses from up to ten machines per second. With the sleep line, that will drop it to maybe one machine every couple of seconds, which is a big performance hit. So far it appears to work reliably without the sleep line.

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Re^3: Timeouts: Any alternative to alarm in Win32?
by BrowserUk (Patriarch) on Dec 04, 2008 at 00:43 UTC
    Do you see any problem with removing the sleep 1; line from the loop?

    Well, without it, the loop will burn 100% cpu. If you need to go more quickly when the response is available more quickly, use Time::HiRes::usleep and say 25 milliseconds. (Or select<c>undef, undef, undef, 0.025;</c. would do.)

    It'll avoid maxing the cpu but cut the minimum delay to 1/40th. Vary the number to see what you find acceptable. As there is IO involved, I doubt you'll go much more quickly with less than 25 millseconds.

    I will test it under Linux when I get back to my office.

    Be aware that I have no idea whether that ioctl number (0x8004667e), which is the key to the approach, will work on any system other than Win32. It might, but don't be surprised if it doesn't. Alternatively, if it does, please post to let me (us) know. It's always good to know these things.


    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.

      Yes, 0x8004667e did work under Linux, which actually surprised me. So the ioctl line works for both platforms, though the timeout doesn't.

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