Initialize the size of array but face OutOfmemoryException

[macneed]

i wrote a program that have a large size array, but the size is change often
(about 3 -4 mins)

the program like that:

public class MemoryArray
{
public float[,,] MM;

public MemoryArray(int Size)
{
MM = new float[Size, 10000, 10000];
}
}

static void Main(string[] args)
{
int[] SizeArray = { 100, 200, 300, 400 };
MemoryArray MA = new MemoryArray(1);
int i=0;

while (true)
{
MA = null; // I try to use it to release memory
GC.Collect();

MA = new MemoryArray(Siz eArray[i++%4];

[Marc Gravell]

Re: Initialize the size of array but face OutOfmemoryExce ption

Well, just a single 10k-by-10k of float is ~380MB; if you have another
dimension too... ouch.

so you are going to put some enormous pressure on the GC, and you'll
probably fragment the Large Object Heap too. It might last a *bit*
longer on Win64 with a lot of memory, but it would be better to not need
such a big buffer.

Dare I ask what this is for?

Marc

[Pavel Minaev]

Re: Initialize the size of array but face OutOfmemoryExce ption

On Sep 18, 3:06 pm, "macneed" <macn...@yahoo. com.hkwrote:

i wrote a program that have a large size array, but the size is change often
(about 3 -4 mins)
>
the program like that:
>
public class MemoryArray
{
    public float[,,] MM;
>
    public MemoryArray(int Size)
    {
        MM = new float[Size, 10000, 10000];
    }
>
}
>
static void Main(string[] args)
{
    int[] SizeArray = { 100, 200, 300, 400 };
    MemoryArray MA = new MemoryArray(1);
    int i=0;
>
    while (true)
    {
        MA = null; // I try to use it to release memory
        GC.Collect();
>
        MA = new MemoryArray(Siz eArray[i++%4];
        .
        .
        .
>
    }
>
}
>
But the program seems can't release memory,
it alway break at below line after running a period of time
        MA = new MemoryArray(Siz eArray[i++%4];
and return a outofmemoryexce ption

My guess would be that it happens because GC.Collect() is asynchronous
- it returns immediately, and the collection is started on a different
thread. There's no guarantee that it completes when you next execute
new[]. Not to mention that Collect() explicitly does not guarantee
that all memory will be reclaimed.

[Marc Gravell]

Re: Initialize the size of array but face OutOfmemoryExce ption

I just noticed that the other dimension *starts* at 100...

100 x 10000 x 10000 x 4 = ~37GB

That is some /serious/ memory (unless my math is wrong)

Marc

[Marc Gravell]

Re: Initialize the size of array but face OutOfmemoryExce ption

My guess would be that it happens because GC.Collect() is asynchronous

- it returns immediately, and the collection is started on a different
thread.

Well, GC takes priority (i.e. suspends) your threads... but as you say,
it isn't obliged to do *anything*. You can ask it a bit more forcefully:

GC.Collect(GC.M axGeneration, GCCollectionMod e.Forced);

You can also play with LatencyMode - but ultimately it is not
recommended to mess with GC; let it do what it does best. If you are
fighting GC, there is a good bet you are simply trying to use too much
momory (or have a leak*).

Marc

*=meaning: you have left objects accidentally referenced, for example
from a static event.

[Marc Gravell]

Re: Initialize the size of array but face OutOfmemoryExce ption

See also: http://blogs.msdn.com/joshwil/archiv...10/450202.aspx

[Brian Gideon]

Re: Initialize the size of array but face OutOfmemoryExce ption

On Sep 18, 6:06 am, "macneed" <macn...@yahoo. com.hkwrote:

i wrote a program that have a large size array, but the size is change often
(about 3 -4 mins)
>
the program like that:
>
public class MemoryArray
{
    public float[,,] MM;
>
    public MemoryArray(int Size)
    {
        MM = new float[Size, 10000, 10000];
    }
>
}
>
static void Main(string[] args)
{
    int[] SizeArray = { 100, 200, 300, 400 };
    MemoryArray MA = new MemoryArray(1);
    int i=0;
>
    while (true)
    {
        MA = null; // I try to use it to release memory
        GC.Collect();
>
        MA = new MemoryArray(Siz eArray[i++%4];
        .
        .
        .
>
    }
>
}
>
But the program seems can't release memory,
it alway break at below line after running a period of time
        MA = new MemoryArray(Siz eArray[i++%4];
and return a outofmemoryexce ption
>
how can i release a array allocated memory and reset the size of it?
>
THANKS

Wow...a 100 * 10000 * 10000 array! Even if you allocated your entire
harddrive for the page file (using a 64-bit OS would be a given) I
still don't think that would work.

I've got to ask...what could you possibly be doing?