Name: akC45999 Date: 10/01/98



Description of the class java.lang.ref.SoftReference reads:

  All soft references to softly-reachable objects are guaranteed to have
  been cleared before the virtual machine throws an OutOfMemoryError.


However, the attached test shows that a soft reference might not be cleared
before OutOfMemoryError is thrown:

------------------------- file SoftReference0101.java
import java.io.PrintStream;
import java.lang.ref.*;


public class SoftReference0101 {

  public static int run(String argv[], PrintStream out) {
SoftReference ref=new SoftReference(new Object());

Object[] memWaste=null;
int arrSize, arrSizeNext=100000;

eatMem:
for (;;) {
arrSize=arrSizeNext;
try {
Object [] newMemWaste=new Object[arrSize];
out.println("allocation of "+arrSize+": succeeded.");
newMemWaste[0]=memWaste;
memWaste=newMemWaste;
if (ref.get()==null) break eatMem; // test passed
arrSizeNext=arrSize*2;
} catch (OutOfMemoryError e) {
out.println("allocation of "+arrSize+": failed.");
if (ref.get()==null) break eatMem; // test passed
out.println("SoftReference.get()!=null");
return 2;
}
}
out.println("passed");
    return 0;
  }

  public static void main(String args[]) {
run(args, System.out);
  }

}

---------------------------------

Running the test:

novo64% java -fullversion
java full version "JDK-1.2fcs-L"
novo64% javac SoftReference0101.java
novo64% java SoftReference0101
allocation of 100000: succeeded.
allocation of 200000: succeeded.
allocation of 400000: succeeded.
allocation of 800000: succeeded.
allocation of 1600000: succeeded.
allocation of 3200000: succeeded.
allocation of 6400000: succeeded.
allocation of 12800000: failed.
SoftReference.get()!=null
novo64%

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