Fill Queue with Files! 2

[FOR111]

Hi all,

I'm very new to Java and i need a small helping hand..just to get the ball rolling! I need to test the Garbage collection if its leaking memory, and they told me to create a simple queue of 1000, and fill them with a 100K file. Then loop endlesly pushing a new file and popping an old..and this should be recursive.

I'm using Java 1.506..just in case.

Thanks very much for any help! I would be much obliged for any help you could fork out!

Nick

 

[Diancecht]

I can assure the garbage collection works OK

Some links that can help you

http://java.sun.com/docs/books/tutorial/essential/io/

http://java.sun.com/j2se/1.4.2/docs/api/java/util/Stack.html

Btw, I don't understand why using files, the file is not loaded into memory, AFAIK.

Cheers,
Dian

 

[FOR111]

Hi Dian

thanks for your reply.

It seems that our system is having some memory leak somewhere as memory is being consumed by the miniute, and they want to verify if its the Garbage collection that's at fault (since this version had a bug which was then solved in v1.508) or our system!

Thanks
Nick

 

[Diancecht]

Oh, sorry, I thought you were doing that as an exercise to learn Java, so it was just a joke.

I can offer you some more options:

1.- Do some profiling on the leaking machine, measuring the memory to test if it's really Java who is consuming memory. If so, use a profile monitor like JProbe to see which objects are consuming the memory.

2.- Update to 1.5 to test if the fix arranges the problem.

Anyway, if you tell us which is the bug, maybe we can offer any other sollution.

Cheers,
Dian

 

[FOR111]

Hi again,

No though i'm actually learning java in the process..i'm more of a c++ developer though i'm still finding the syntax quite quirky hehe!

Thanks for the suggestion i will defintly put the JProbe suggestion forward to my collegue (now he is a Java guru hehe!)



Cheers
Nick

 

[FOR111]

Just a small question:

What is the best way of creating a 100K dump temporary file?


Thanks
Nick

 

[Diancecht]

Something like

try {
        BufferedWriter out = new BufferedWriter(new FileWriter("outfilename"));
        for (int i=0;i<100000;i++)
           out.write("a");
        out.close();
    } catch (IOException e) {
    }

would do the job.

Cheers,
Dian

 

[FOR111]

yeah i did that..though its very slow!

Thought there is a better way off!

Tahnks anyways!
Nick

 

[sedj]

well another way is :

byte[] data = new byte[100000];
for (int i = 0; i < data.length; i++) {
  data[i] = (byte)1;
}
FileOutputStream fos = new FileOutputStream("somefile.txt");
fos.write(data);
fos.flush();
fos.close();

--------------------------------------------------
Free Java/J2EE Database Connection Pooling Software

http://www.primrose.org.uk

 

[Diancecht]

Forget about the buffer then

char[] buffer = new char[100000];
java.util.Arrays.fill(buffer,'a');
try {
        FileWriter fw = new FileWriter("outfilename"));
        fw.write(buffer);
        fw.close();
    } catch (IOException e) {
    }

Cheers,
Dian

 

[FOR111]

Great..guys i thank you alot!

It got better now and its working great!

Cheers
Nick