Name: agR10195 Date: 02/13/2004



The following test IAE sets collection usage threshold that is equal to 0
for each pool, if the pool supports collection usage thresholds.

The spec for Tiger-b38 says:

    void setCollectionUsageThreshold(long threhsold)
    
    ...
    
    Throws: IllegalArgumentException - if limit is negative or greater than the
            maximum amount of memory that this memory pool can use.
            
Aslo, the spec for MemoryPoolMBean says:

    4. Collection Usage Threshold
    
    If the collection usage threshold is set to zero, this checking is
    disabled on this memory pool. Default value is zero.
    
So, zero is a legal argument for setCollectionUsageThreshold() method. I
believe, the spec for the setCollectionUsageThreshold(long) should describe
it as well as the spec for MemoryPoolMBean class.

However, the test reveals that setCollectionUsageThreshold() may throw
IllegalArgumentException for threshold that is equal to 0.

java.lang.IllegalArgumentException: Invalid threshold: 0 > max (-1).
java.lang.IllegalArgumentException: Invalid threshold: 0 > max (0).
java.lang.IllegalArgumentException: Invalid threshold: 0 > max (59703296).
java.lang.IllegalArgumentException: Invalid threshold: 0 > max (67108864).

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

public class IAE {
    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(" does not support collection usage "
                                 + "thresholds");
                continue;
            }
            System.out.println(" supports CollectionUsage usage thresholds");

            try {
                pool.setCollectionUsageThreshold(0);
            } catch (Exception e) {
                System.out.println(" e = " + e);
            }
        }
    }
}

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

0 pool Code Cache
  does not support collection usage thresholds

1 pool Eden Space
  supports CollectionUsage usage thresholds
  e = java.lang.IllegalArgumentException: Invalid threshold: 0 > max (-1).

2 pool Survivor Space 1
  supports CollectionUsage usage thresholds
  e = java.lang.IllegalArgumentException: Invalid threshold: 0 > max (-1).

3 pool Survivor Space 2
  supports CollectionUsage usage thresholds
  e = java.lang.IllegalArgumentException: Invalid threshold: 0 > max (0).

4 pool Tenured Gen
  supports CollectionUsage usage thresholds
  e = java.lang.IllegalArgumentException: Invalid threshold: 0 > max (59703296).

5 pool Perm Gen
  supports CollectionUsage usage thresholds
  e = java.lang.IllegalArgumentException: Invalid threshold: 0 > max (67108864).

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