How to trace an OutOfMemoryError?

Thread view:

Princess Morgiah - 04 Apr 2004 12:09 GMT

Hi everyone,

I'm stuck with a little application I wrote some time ago. After using it
for a while, the application hangs and an OutOfMemoryError is written to the
console (java.lang.OutOfMemoryError is all that is written).

Since there is no stacktrace, no extra information and thus no way of
knowing where the error comes from, how do I trace this back to it's origin?

I have tried to increase the memory available to the JVM, setting it to a
minimum of 256M and a maximum of 512M, but to no avail. And even if it did
work, this would not be needed - the application itself should be very happy
with a maximum of 1M!

There are some parts of the application that could be at fault - database
stuff, creating a lot of objects, etc... I've had a look at them but all
seems to be in order.

Any ideas?

Princess Morgiah

Reply to this Message

Ryan Stewart - 04 Apr 2004 13:57 GMT

> Hi everyone,
>
[quoted text clipped - 17 lines]
>
> Princess Morgiah

First, look for infinite loops. Then use a logger to track where you are in
the execution.

Reply to this Message

Princess Morgiah - 04 Apr 2004 20:39 GMT

> First, look for infinite loops. Then use a logger to track where you are in
> the execution.

Thanks, yours turns out to be very sound advice - I already had a logger in
place but removed some log calls inside pieces of 'trusted code'.

As it turns out, one of those loops kept reading from an invalid stream,
ignoring invalid input without providing a way out, hence the accepting
buffer grew and grew with the expected result.

Thanks again Ryan!

Princess Morgiah

Reply to this Message

Knute Johnson - 04 Apr 2004 19:29 GMT

> Hi everyone,
>
[quoted text clipped - 17 lines]
>
> Princess Morgiah

Wrap all of the code in:

try {
} catch (Exception e) {
e.printStackTrace();
}

Signature

Knute Johnson
email s/nospam/knute/
Molon labe...

Reply to this Message

Inertia_sublimation - 04 Apr 2004 20:37 GMT

> > Hi everyone,
> >
[quoted text clipped - 24 lines]
> e.printStackTrace();
> }

Isnt java.lang.OutOfMemoryError an Error, and not an Exception?
If so, I think that catch statement should be instead:

catch(Throwable e)

or catch(Error e) if the OP wants to catch only that error.

Reply to this Message

Princess Morgiah - 04 Apr 2004 20:46 GMT

> Wrap all of the code in:
>
> try {
> } catch (Exception e) {
> e.printStackTrace();
> }

Thanks for the suggestion, I tried it before but it turns out that I was
tracing the wrong part of the code.

A small correction is in place here, however:
--- incorrect ---
public class Oome
{
public Oome()
{
try
{
StringBuffer b = new StringBuffer();
while (true)
{
b.append("x");
}
}
catch (Exception e)

System.out.println("D'oh!");
}
}

public static void main(String [] args)
{
new Oome();
}
}
---

This will never show the famous Simpson quote, yet:
--- correct ---
catch (OutOfMemoryError oome)
{
System.out.println("D'oh!");
}
---

will give Homer a chance to speak.

Regards,

Princess Morgiah

Reply to this Message

How to trace an OutOfMemoryError?

Free Magazines