How to get stack trace of an exception in Scala to print it?

Question

In a program of mine I'd like to catch all exceptions and explicitly print them (to be able to proceed with finally while still seeing exceptions).

So I've tried this:

try {
  ...
}
catch {
  case ex : Exception => {
    println ("\n" + ex)
    println ("\n" + ex.getStackTrace + "\n")
  }
}
finally {
  ...
}

But this (using getStackTrace) itself causes "java.lang.OutOfMemoryError: PermGen space". What am I doing wrong? I am sure I have plenty of free JVM heap memory free before getting this (as I've tried causing an exception in the very beginning of the program).

Answer 1

Sounds like you need to allocate more permgen space. In Java you do this with a JVM argument:

-XX:MaxPermGen=256m

You can set JVM args to be used by Scala by setting an environment variable:

JAVA_OPTS="-XX:MaxPermGen=256m"

Answer 2

I think you should post an exact, standalone working example of this because this works for me using 2.8.0 (i.e. exhibits no memory problems at all):

scala> def foo( f : () => Unit) : Unit = try {
     | f()
     | } catch { case e : Exception => println("H" + e.getStackTrace) }
foo: (f: () => Unit)Unit

scala> foo(() => throw new NullPointerException)
H[Ljava.lang.StackTraceElement;@30a4effe

I wonder whether you have an exception which is its own cause? Conversely it may be the case that your program is running very low on memory (32Mb is the default on a client-class machine by the way) and you have a very deep stack (not uncommon in scala-land!)