Null buffer refs when closing SnappyOutputStream.

src/main/java/org/xerial/snappy/SnappyOutputStream.java

@@ -65,8 +65,9 @@ public class SnappyOutputStream extends OutputStream {
     private final BufferAllocator inputBufferAllocator;
     private final BufferAllocator outputBufferAllocator;
 
-    protected final byte[] inputBuffer;
-    protected final byte[] outputBuffer;
+    // The input and output buffer fields are set to null when closing this stream:
+    protected byte[] inputBuffer;
+    protected byte[] outputBuffer;
     private int inputCursor = 0;
     private int outputCursor = 0;
     private boolean closed;
@@ -340,6 +341,8 @@ public class SnappyOutputStream extends OutputStream {
             closed = true;
             inputBufferAllocator.release(inputBuffer);
             outputBufferAllocator.release(outputBuffer);
+            inputBuffer = null;
+            outputBuffer = null;
         }
     }
 

src/test/java/org/xerial/snappy/SnappyOutputStreamTest.java

@@ -30,10 +30,12 @@ import java.io.BufferedInputStream;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.lang.ref.WeakReference;
 
 import org.junit.Test;
 import org.xerial.snappy.buffer.BufferAllocatorFactory;
 import org.xerial.snappy.buffer.CachedBufferAllocator;
+import org.xerial.snappy.buffer.DefaultBufferAllocator;
 import org.xerial.util.FileResource;
 import org.xerial.util.log.Logger;
 
@@ -225,6 +227,18 @@ public class SnappyOutputStreamTest
         }
     }
 
+    @Test
+    public void closingStreamShouldMakeBuffersEligibleForGarbageCollection() throws IOException {
+        ByteArrayOutputStream b = new ByteArrayOutputStream();
+        SnappyOutputStream os = new SnappyOutputStream(b, 4095, DefaultBufferAllocator.factory);
+        WeakReference<byte[]> inputBuffer = new WeakReference<byte[]>(os.inputBuffer);
+        WeakReference<byte[]> outputBuffer = new WeakReference<byte[]>(os.inputBuffer);
+        os.close();
+        System.gc();
+        assertNull(inputBuffer.get());
+        assertNull(outputBuffer.get());
+    }
+
     @Test
     public void longArrayCompress() throws Exception {
         long[] l = new long[10];