Memory Eating - Dangerous?

This is a discussion on Memory Eating - Dangerous? within the C++ Programming forums, part of the General Programming Boards category; I was looking into memory managment for C/C++ and found that it can make your computer go bonkers if you ...

  1. #1
    Registered User Machewy's Avatar
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    Memory Eating - Dangerous?

    I was looking into memory managment for C/C++ and found that it can make your computer go bonkers if you don't watch it.

    Anyways, take a look at this thing I put together:

    Code:
    #include <windows.h>
    
    int main()
    {
       FreeConsole();
       int x = 1;
       while(x==1)
       {
          int* fat = new int[999];
          int* ugly = new int[999];
       }
       return 0;
    }
    If you run it, you will notice that your computer will slow down immediatly! And if you run it too long, it will just stop your system totally. My question is: Can *poor* memory management like this damage your system?

    Best Regards,
    Machewy
    "All things come to an end"

  2. #2
    Toaster Zach L.'s Avatar
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    In general, it won't provide any lasting effects that a reboot won't cure.

    Most modern OS's provide virtual memory space for each process, so that processes cannot access each other's memory. The only real potential that I can think of for lasting damage is if something that you don't own gets overwritten by your program, and then inadvertently written to disk (before the system just crashes). However, with the virtual memory space, that is not really a problem. Perhaps on a few (probably older) systems it is possible, but I find it more likely that it would just cause the system to shutdown.

    There are, however, good reasons to avoid poor memory management.
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  3. #3
    Registered User major_small's Avatar
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    I think the general rule is to turn off the computer (and power supply) for 30 seconds to clear all RAM... I've had some pretty bad memory leaks, and I've created programs like the one you just wrote just to see what would happen... I have XP, so all that happened was windows killed the process and everything was all right again...

    but no, I dont' think it will do any real damage to your computer...
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    Guest Sebastiani's Avatar
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    When you request dynamic memory, *all* that happens is that the OS's memory manager looks for an available chunk of ram of that size (or greater since it will be aligned to some boundary), and then honors the request if it is indeed available or else denies it if not. And though Windows proportedly limits the amount of available dynamic (heap) memory (based on a value that is stored directly in the executable) I have personally seen it go far past this amount - as if it were a mere suggestion.

    As for permanent damage, that is a total myth. It won't overwrite any out-of-range piece of memory, either. Nothing a simple reboot can't cure.

  5. #5
    Super Moderator VirtualAce's Avatar
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    All that does is allocate memory that is never returned to the system. When it runs out of memory the OS will shut it down because there is no more heap...then on return the memory is never given back to the OS.

    On XP, this should not be a problem as it is supposed to run code within its own 'fence' per se. So your program will never allocate another processes memory, data, and/or code - theoretically.

    In real mode, this would shut the system down totally and DOS would crash - the next time you tried to run it. Since new is basically malloc(sizeof(<object>)) malloc will return an error code indicating that no more heap memory is available. Since you never return it to the system - it is very likely that on returning from this code, your Borland Turbo IDE or DOS itself will crash.

    No physical damage, however, is done to the system.

    A reboot or reset will fix it.

  6. #6
    Nor
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    h ֆhr s Nor's Avatar
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    if your looking for a way to mess up your pc
    take a mice of metal(doesnt matter what type) and a metal grinder(black'n'Decker)
    hold the metal over your open case(on its side and the power on) then grind it down to nothing.
    that should do it. if it doesnt its an act of god and your pc will live forever
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  7. #7
    Cat without Hat CornedBee's Avatar
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    A very good idea for killing your PC would be to search for that small red switch on the back of your PSU and switch it to the other position. Works wonderfully here in Europe, maybe not as well in the USA.
    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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  8. #8
    Its not rocket science vasanth's Avatar
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    Originally posted by CornedBee
    A very good idea for killing your PC would be to search for that small red switch on the back of your PSU and switch it to the other position. Works wonderfully here in Europe, maybe not as well in the USA.

    I always experimented with my system.. did that and blew my SMPS.. nothing more than that... got it replaced for Rs 400 (10 $)....

  9. #9
    Cat without Hat CornedBee's Avatar
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    You never know - kinda like Russian roulette
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    Confused
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    I'd like to ask, FreeConsole() "detaches the calling process from its console", what does this mean / imply ? Thanks.

  11. #11
    Registered User major_small's Avatar
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    http://faq.cprogramming.com/cgi-bin/...&id=1043284385
    ^try number 5 for destroying your computer
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    Rabite SirCrono6's Avatar
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    Ooooh! Oooh! I know! How to kill your computer:

    Step 1: Get a REALLY, REALLY BIG magnet.

    Step 2: Put the magnet on the motherboard.

    Result: Total and utter computer memory death

    - SirCrono6
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  13. #13
    Cat without Hat CornedBee's Avatar
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    FreeConsole.

    Since a child process inherits the console from its parent, more than one process can "own" a console. Calling FreeConsole causes a process to give up its ownership to the console. If there are no other owners of the console, it is destroyed.
    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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  14. #14
    Confused
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    If, when a console has no owner, it is destroyed, why would it be called in this program, if all you want to do is create a massive memory leak ?

  15. #15
    Cat without Hat CornedBee's Avatar
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    To hide any trace of the program. If there's a console, the app can easily be killed without even using the task manager.
    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."
    - Flon's Law

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