Name: agR10195 Date: 02/13/2004



The following test UOE reveals that getCollectionUsageThreshold() does not
throw UnsupportedOperationException, if the pool does not support collection
usage threshold:

    long getCollectionUsageThreshold()
    
    Returns the collection usage threshold value of this memory pool in
    bytes. The default value is zero. The collection usage threshold can be
    changed via the setCollectionUsageThreshold method.
    
    Throws: UnsupportedOperationException - if this memory pool does not
             support a collection usage threshold.

Instead of exception, the method returns -1 (like getUsageThreshold() does)
against Tiger-b38.

import java.io.*;
import java.lang.management.*;
import java.util.*;

public class UOE {
    public static void main(String[] argv) {
        List pools = ManagementFactory.getMemoryPoolMBeans();

        for (int i = 0; i < pools.size(); i++) {
            MemoryPoolMBean pool = (MemoryPoolMBean) pools.get(i);
            System.out.println("\n" + i + " pool " + pool.getName());

            boolean isSupported = pool.isCollectionUsageThresholdSupported();

            if (isSupported) {
                System.out.println(" supports collection usage thresholds");
                continue;
            }
            System.out.println(" does not support collection usage "
                             + "thresholds");

            long value = 0;
            try {
                value = pool.getCollectionUsageThreshold();
                System.out.println(" ERROR: threshold = " + value);
            } catch (UnsupportedOperationException e) {
                System.out.println(" OK: e = " + e);
            }
        }
    }
}

% ../jdk1.5.0-b38/solaris-sparc/bin/java UOE

0 pool Code Cache
  does not support collection usage thresholds
  ERROR: threshold = -1

1 pool Eden Space
  supports collection usage thresholds

2 pool Survivor Space 1
  supports collection usage thresholds

3 pool Survivor Space 2
  supports collection usage thresholds

4 pool Tenured Gen
  supports collection usage thresholds

5 pool Perm Gen
  supports collection usage thresholds

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