finding the memory footprint of DOMDocument

[muralibala68]

Hi,

Is there a way to find the total size of the DOMDocument created using
xerces C++ API (without serializing it) ?

Thanks.

 

[Codedigestion]

Hi,

Is there a way to find the total size of the DOMDocument created using
xerces C++ API (without serializing it) ?

Thanks.

Peace,

I'm working on the same problem myself. I've got an interesting piece
of software in development to compare the different parsers to see the
time taken and memory footpaths of the built DOM's. I figured out a
way to use java.lang.Runtime to get memory details of the JVM to
indirectly assert out the size, but, this is NOT an ABSOLUTE method.
Meanwhile, I've happened across the following code and you may be able
to apply it, as I intend to myself for the same reaon in a few days.
Just haven't had the time to study the code yet. Let me know how it
comes along, eh....

public class Sizeof
{
public static void main (String [] args) throws Exception
{
// Warm up all classes/methods we will use
runGC ();
usedMemory ();

// Array to keep strong references to allocated objects
final int count = 100000;
Object [] objects = new Object [count];

long heap1 = 0;

// Allocate count+1 objects, discard the first one
for (int i = -1; i < count; ++ i)
{
Object object = null;

// Instantiate your data here and assign it to object

object = new Object ();
//object = new Integer (i);
//object = new Long (i);
//object = new String ();
//object = new byte [128][1]

if (i >= 0)
objects = object;
else
{
object = null; // Discard the warm up object
runGC ();
heap1 = usedMemory (); // Take a before heap snapshot
}
}

runGC ();
long heap2 = usedMemory (); // Take an after heap snapshot:

final int size = Math.round (((float)(heap2 - heap1))/count);
System.out.println ("'before' heap: " + heap1 +
", 'after' heap: " + heap2);
System.out.println ("heap delta: " + (heap2 - heap1) +
", {" + objects [0].getClass () + "} size = " + size + "
bytes");

for (int i = 0; i < count; ++ i) objects = null;
objects = null;
}

private static void runGC () throws Exception
{
// It helps to call Runtime.gc()
// using several method calls:
for (int r = 0; r < 4; ++ r) _runGC ();
}

private static void _runGC () throws Exception
{
long usedMem1 = usedMemory (), usedMem2 = Long.MAX_VALUE;
for (int i = 0; (usedMem1 < usedMem2) && (i < 500); ++ i)
{
s_runtime.runFinalization ();
s_runtime.gc ();
Thread.currentThread ().yield ();

usedMem2 = usedMem1;
usedMem1 = usedMemory ();
}
}

private static long usedMemory ()
{
return s_runtime.totalMemory () - s_runtime.freeMemory ();
}

private static final Runtime s_runtime = Runtime.getRuntime ();

} // End of class

 

[Codedigestion]

Hi,

Is there a way to find the total size of the DOMDocument created using
xerces C++ API (without serializing it) ?

Thanks.

Peace,

I'm working on the same problem myself. I've got an interesting piece
of software in development to compare the different parsers to see the
time taken and memory footpaths of the built DOM's. I figured out a
way to use java.lang.Runtime to get memory details of the JVM to
indirectly assert out the size, but, this is NOT an ABSOLUTE method.
Meanwhile, I've happened across the following code and you may be able
to apply it, as I intend to myself for the same reaon in a few days.
Just haven't had the time to study the code yet. Let me know how it
comes along, eh....

public class Sizeof
{
public static void main (String [] args) throws Exception
{
// Warm up all classes/methods we will use
runGC ();
usedMemory ();

// Array to keep strong references to allocated objects
final int count = 100000;
Object [] objects = new Object [count];

long heap1 = 0;

// Allocate count+1 objects, discard the first one
for (int i = -1; i < count; ++ i)
{
Object object = null;

// Instantiate your data here and assign it to object

object = new Object ();
//object = new Integer (i);
//object = new Long (i);
//object = new String ();
//object = new byte [128][1]

if (i >= 0)
objects = object;
else
{
object = null; // Discard the warm up object
runGC ();
heap1 = usedMemory (); // Take a before heap snapshot
}
}

runGC ();
long heap2 = usedMemory (); // Take an after heap snapshot:

final int size = Math.round (((float)(heap2 - heap1))/count);
System.out.println ("'before' heap: " + heap1 +
", 'after' heap: " + heap2);
System.out.println ("heap delta: " + (heap2 - heap1) +
", {" + objects [0].getClass () + "} size = " + size + "
bytes");

for (int i = 0; i < count; ++ i) objects = null;
objects = null;
}

private static void runGC () throws Exception
{
// It helps to call Runtime.gc()
// using several method calls:
for (int r = 0; r < 4; ++ r) _runGC ();
}

private static void _runGC () throws Exception
{
long usedMem1 = usedMemory (), usedMem2 = Long.MAX_VALUE;
for (int i = 0; (usedMem1 < usedMem2) && (i < 500); ++ i)
{
s_runtime.runFinalization ();
s_runtime.gc ();
Thread.currentThread ().yield ();

usedMem2 = usedMem1;
usedMem1 = usedMemory ();
}
}

private static long usedMemory ()
{
return s_runtime.totalMemory () - s_runtime.freeMemory ();
}

private static final Runtime s_runtime = Runtime.getRuntime ();

} // End of class

OOPS, you mentioned C++ - This is Java Code... SORRY!

 

[Codedigestion]

Hi,

Is there a way to find the total size of the DOMDocument created using
xerces C++ API (without serializing it) ?

Thanks.

I believe there's a method available called, sizeOf() which would do it
for you.

 

[Joe Kesselman]

I believe there's a method available called, sizeOf() which would do it
for you.

Not according to http://xml.apache.org/xerces-c/apiDocs/functions.html
and I don't see anything else in there which will directly tell you this.

Since the memory manager for Xerces is a plug-in API, you could try
supplying an instrumented version thereof and see how many bytes are
being allocated and deallocated. Remember to consider alignment issues,
which will depend the platform, compiler, and compiler settings.