Structure memory usage?

[James]

Hi,

I need help with a couple of questions, I have create and structure like:
Structure byteArray
Public byteA() As Byte

End Structure

Public ptrArray() As byteArray

I have redim ptrArray(1000000) and the memory usage in Windows Task Manager
shows an increase of 4MB bytes that seems OK.

Then I have done

for intI=1 to 1000000

Redim ptrArray(intI).byteA(1)

next intI

And now the memory in task manager shows and increase of almost 16 MB,
instead of 1MB.

QUESTIONS:

1) It seems that an structure increase the memory usage (I suppose it create
internal variables). Is there any other way that I can have an "Array of
Arrays" that can be dinamically increase without the memory overcost of
using a structure?.

2) Is ther any way (not Windows Task Manager) to know how much memory a
variable, or structure is using in vb.net?.

Thanks,

James

 

[Armin Zingler]

Hi,

I need help with a couple of questions, I have create and structure
like:
Structure byteArray
Public byteA() As Byte

End Structure

Public ptrArray() As byteArray

I have redim ptrArray(1000000) and the memory usage in Windows Task
Manager
shows an increase of 4MB bytes that seems OK.

Then I have done

for intI=1 to 1000000

Redim ptrArray(intI).byteA(1)

next intI

And now the memory in task manager shows and increase of almost 16
MB,
instead of 1MB.

You probably mean 2 MB because arrays are zero-based, and an upper bound of
1 creates the items 0 and 1.

QUESTIONS:

1) It seems that an structure increase the memory usage (I suppose
it create
internal variables). Is there any other way that I can have an
"Array of
Arrays" that can be dinamically increase without the memory overcost
of
using a structure?.

I don't know if it solves the memory issue, but and array of arrays can be
declared this way:

Public ptrArray()() As byte

This is an array of byte-arrays.

Public ptrArray(999999)() As byte

This is an array that can point to 1,000,000 byte arrays. Each of the 1 mio.
items is still Nothing.

Redim ptrArray(0)(99)

Now Item 0 points to an array of 100 bytes.

2) Is ther any way (not Windows Task Manager) to know how much memory a
variable, or structure is using in vb.net?.

I have no reliable answer to this. I can only point to

VB language reference -> data types -> data type summary.

There are few words about the memory consumption of arrays - maybe this
helps. Using that information: 1,000,000 * (12 + 8 + 2) = ~22 MB. But as I
said, I can not say this for sure, above all because the automatic memory
management is a "black box". Maybe you can ask this in the
microsoft.public.dotnet.framework.clr group because it is not really VB.Net
related.


Armin

 

[Herfried K. Wagner [MVP]]

2) Is ther any way (not Windows Task Manager) to know how much memory a
variable, or structure is using in vb.net?.

In addition to the other replies:

Allocation Profiler src
<URL:http://www.gotdotnet.com/Community/...mpleGuid=3254325d-a4aa-4bb3-aa86-c72d5104ec74>

CLR Profiler (v2.0)
<URL:http://www.microsoft.com/downloads/...52-D7F4-4AEB-9B7A-94635BEEBDDA&displaylang=en>