Name: jl125535 Date: 09/04/2003


A DESCRIPTION OF THE REQUEST :
When starting a Java program, Java needs to load lots of Java classes. java.lang.ClassLoader.findBootstrapClass() and java.net.URLClassLoader.findClass() both throw ClassNotFoundExceptions for each application class or class from third party libraries to be loaded.

I modified java.lang.Throwable.java (see attached source code and method _logThrowable() ) to print information about ClassNotFoundExceptions to stdout. Compile it and put the .class file in a newly created empty directory-tree c:\jdkpatch\java\lang.

When starting SwingSet with
    java -Xbootclasspath/p:c:\jdkpatch -jar SwingSet2.jar
285 instances of ClassNotFoundException are thrown.

In our application, consisting of thousands of classes, thousands of ClassNotFoundExceptions are thrown during startup.

JUSTIFICATION :
Throwing and catching exceptions slows down the application. In addition to that for keeping stack-traces objects need to be created and garbage-collected. This has an impact on application startup time.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I suggest using return-codes instead of exceptions wherever possible. e.g. java.lang.ClassLoader.findBootstrapClass0() could simply return null if the class was not found.

---------- BEGIN SOURCE ----------
My changes to Throwable.java:
- added new static variable "count"
- added new method "_logThrowable" (please note that the method's
  implementation is slightly different bug 4917307)
- called method "_logThrowable" from the constructor

Here is the code:

    private static int count = 0;
    private void _logThrowable()
    {
        if (getClass() == ClassNotFoundException.class)
        {
            count++;
            System.out.println("ClassNotFoundException #" + count);
            printStackTrace();
        }
    }
    public Throwable() {
        fillInStackTrace();
        _logThrowable();
    }
    public Throwable(String message) {
        fillInStackTrace();
        detailMessage = message;
        _logThrowable();
    }
    public Throwable(String message, Throwable cause) {
        fillInStackTrace();
        detailMessage = message;
        this.cause = cause;
        _logThrowable();
    }
    public Throwable(Throwable cause) {
        fillInStackTrace();
        detailMessage = (cause==null ? null : cause.toString());
        this.cause = cause;
        _logThrowable();
    }

---------- END SOURCE ----------
(Incident Review ID: 201376)
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