Java program terminates unexpectedly without any error message

Question

I have written a java program which needs to process thousands of text files (all needs to be loaded on memory). It works fine with as many as 123 input files, but when I run it to process around 5000 files, it terminates unexpectedly in the middle of the road, without giving any error message/exception. Can anyone give me clue about what might have gone wrong?

I am using jdk1.6 on Mac OS Leopard having 2GB RAM.

Answer 1

Given that it is your program, I suggest that you do the following:

First, change the main method so that everything is done in a try/catch block that reports all uncaught exceptions; e.g. something like this:

public static void main(String[] arghhhhh) {
    try {
        ...
    } catch (Throwable ex) {
        System.err.println("Uncaught exception - " + ex.getMessage());
        ex.printStackTrace(System.err);
    }
}

Second, look for anywhere that you might "squash" unexpected exceptions by catching them and not reporting them.

Third, look for anywhere that you might call System.exit() silently. This could happen in libraries too ... if you are using a badly written one.

If those measures don't give you answers, try to figure HOW the application is exiting by

• by running from a debugger with breakpoints set at key points, or
• by adding trace print statements at key points.

Answer 2

It seems like you are getting OutofmemoryError.

if it is the case try to increase heap memory size.

java -Xms<initial heap size> -Xmx<maximum heap size>

Answer 3

Are you opening files simultaneously? You might be running out of memory if you are loading too many files at once. If the files are large enough, you might be running out of memory with only a single file open. Also, make sure you are closing the files when you're done with them.

Answer 4

Check if you have any try/catch blocks that do not log exceptions properly.

It could most likely be OutofmemoryError. Make sure the console isn't redirected.

Answer 5

There are mainly two reasons.

1. A "unhandled" system fault has occurred i.e. java.lang.OutOfMemoryError.
2. A "unhandled" application fault has occurred.
3. System.exit has been called.

To deal with these scenarios consider to do the following steps:

• Look in you code for calls to System.exit.

• Ensure that you handles all exceptions in the starting Java stack frame, i.e. Main-method:

  try{ ..code }catch(Throwable t){ t.printStackTrace }

• Ensure that you have control where the stdout and stderr is directed. You may programatically set these to concrete files:

System.setOut(new PrintStream("output.txt")); System.setErr(new PrintStream("err.txt"));

• Start with args as: -Xloggc:gc.log -XX:+PrintGCDetails -XX:+PrintGCTimeStamps