Threading

This is a discussion on Threading within the C# Programming forums, part of the General Programming Boards category; If I access to the same memory adress at the same time it might have a "little" problem right? So ...

  1. #1
    Registered User gavra's Avatar
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    Threading

    If I access to the same memory adress at the same time it might have a "little" problem right?
    So how do I solve it? (like checking if a specific adress is in use..)
    Thanks.
    gavra.

  2. #2
    Banned master5001's Avatar
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    I don't know the C# specific way of doing this, but you can use something called a Semiphore or a Mutex. Well... nifty. I just did a quick google search for "c# semiphore" and this came up.

  3. #3
    Cat without Hat CornedBee's Avatar
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    "Semaphore". The word has nothing to do with "semi".
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
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    Confused Magos's Avatar
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    Take a look at the lock statement
    Beware of deadlocks though
    MagosX.com

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    Malum in se abachler's Avatar
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    Quote Originally Posted by CornedBee View Post
    "Semaphore". The word has nothing to do with "semi".
    Is a semifore just a fo?
    Until you can build a working general purpose reprogrammable computer out of basic components from radio shack, you are not fit to call yourself a programmer in my presence. This is cwhizard, signing off.

  6. #6
    Registered User gavra's Avatar
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    First of all thanks (:
    What is the first argument (Semaphore) meant to be for?
    and if I don't want diffrent threads to use the same adress concurrently I need to set the second argument to 1?
    and one more thing what is the diffrence between "lock statement" and "semaphore"?
    Last edited by gavra; 09-17-2008 at 09:12 AM.
    gavra.

  7. #7
    Malum in se abachler's Avatar
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    Semaphore is a fancy name for a flag. Similar to a critical section. In this context you woudl test the state of the semaphore prior to entering the critical area and wait to procede until the flag is not set. Once enteing the critical area, you set the flag to rpevent other threads form modifying the protected resource, then you operate ont hat resource and when finished you reset the semaphore. Under windows, use CRITICAL_SECTION's. SEMAPHORE's under windows are generally reserved for interprocess locking, CRITICAL_SECTION's are for intraprocess locking.
    Until you can build a working general purpose reprogrammable computer out of basic components from radio shack, you are not fit to call yourself a programmer in my presence. This is cwhizard, signing off.

  8. #8
    Registered User gavra's Avatar
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    When you say it, it seems to be very simple (and logical) but I don't see it that way \:
    What is those counters meant to do?
    and way they use array?
    gavra.

  9. #9
    Kernel hacker
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    You may want to look at the Wiki for semaphore:
    http://en.wikipedia.org/wiki/Semaphore_(programming)

    --
    Mats
    Last edited by matsp; 09-17-2008 at 10:39 AM. Reason: Edit Fix the URL.
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  10. #10
    Registered User gavra's Avatar
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    This page doesn't exist yet.
    gavra.

  11. #11
    Kernel hacker
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    Quote Originally Posted by gavra View Post
    This page doesn't exist yet.
    Because of the parsing of URL's, You have to manually add the missing ). Edit: And I fixed it in the orignal post, so you can click the link.

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    Mats
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    Please don't PM me for help - and no, I don't do help over instant messengers.

  12. #12
    Registered User gavra's Avatar
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    oh thanks but the explanation is only connected with the "theory".
    and why isn't it use only true or false?
    gavra.

  13. #13
    Banned master5001's Avatar
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    Quote Originally Posted by CornedBee View Post
    "Semaphore". The word has nothing to do with "semi".
    Yet when I googled it I did spell semaphore correctly... Go figure. And no, google did not just correct my misspelling. I sleep very little lately... leave me alone guys -_-

  14. #14
    Banned master5001's Avatar
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    Quote Originally Posted by Magos View Post
    Take a look at the lock statement
    Beware of deadlocks though
    Very cool, Magos. I guess C# programmers can be useful afterall.

  15. #15
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    What you are seeking is the pthread_mutex_lock function in C (or a lock { } block in C#), so only one thread can execute a particular piece of code at a time.

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