diff -urN openjdk.orig/jdk/src/share/classes/com/sun/imageio/plugins/png/PNGImageReader.java openjdk/jdk/src/share/classes/com/sun/imageio/plugins/png/PNGImageReader.java
--- openjdk.orig/jdk/src/share/classes/com/sun/imageio/plugins/png/PNGImageReader.java	2010-06-21 17:15:11.000000000 -0400
+++ openjdk/jdk/src/share/classes/com/sun/imageio/plugins/png/PNGImageReader.java	2010-12-23 15:12:24.471446202 -0500
@@ -618,10 +618,15 @@
     private static String inflate(byte[] b) throws IOException {
         InputStream bais = new ByteArrayInputStream(b);
         InputStream iis = new InflaterInputStream(bais);
+
         StringBuilder sb = new StringBuilder(80);
         int c;
-        while ((c = iis.read()) != -1) {
-            sb.append((char)c);
+        try {
+            while ((c = iis.read()) != -1) {
+                sb.append((char)c);
+            }
+        } finally {
+            iis.close();
         }
         return sb.toString();
     }
@@ -1246,13 +1251,26 @@
             destinationBands = param.getDestinationBands();
             destinationOffset = param.getDestinationOffset();
         }
-
+        Inflater inf = null;
         try {
             stream.seek(imageStartPosition);
 
             Enumeration e = new PNGImageDataEnumeration(stream);
             InputStream is = new SequenceInputStream(e);
-            is = new InflaterInputStream(is, new Inflater());
+
+           /* InflaterInputStream uses an Inflater instance which consumes
+            * native (non-GC visible) resources. This is normally implicitly
+            * freed when the stream is closed. However since the
+            * InflaterInputStream wraps a client-supplied input stream,
+            * we cannot close it.
+            * But the app may depend on GC finalization to close the stream.
+            * Therefore to ensure timely freeing of native resources we
+            * explicitly create the Inflater instance and free its resources
+            * when we are done with the InflaterInputStream by calling
+            * inf.end();
+            */
+            inf = new Inflater();
+            is = new InflaterInputStream(is, inf);
             is = new BufferedInputStream(is);
             this.pixelStream = new DataInputStream(is);
 
@@ -1285,6 +1303,10 @@
             }
         } catch (IOException e) {
             throw new IIOException("Error reading PNG image data", e);
+        } finally {
+            if (inf != null) {
+                inf.end();
+            }
         }
     }
 
diff -urN openjdk.orig/jdk/src/share/classes/com/sun/imageio/plugins/png/PNGImageWriter.java openjdk/jdk/src/share/classes/com/sun/imageio/plugins/png/PNGImageWriter.java
--- openjdk.orig/jdk/src/share/classes/com/sun/imageio/plugins/png/PNGImageWriter.java	2010-06-21 17:15:11.000000000 -0400
+++ openjdk/jdk/src/share/classes/com/sun/imageio/plugins/png/PNGImageWriter.java	2010-12-23 15:12:24.472446225 -0500
@@ -244,13 +244,17 @@
     }
 
     public void finish() throws IOException {
-        if (!def.finished()) {
-            def.finish();
-            while (!def.finished()) {
-                deflate();
+        try {
+            if (!def.finished()) {
+                def.finish();
+                while (!def.finished()) {
+                    deflate();
+                }
             }
+            finishChunk();
+        } finally {
+            def.end();
         }
-        finishChunk();
     }
 
     protected void finalize() throws Throwable {
@@ -928,23 +932,24 @@
     // Use sourceXOffset, etc.
     private void write_IDAT(RenderedImage image) throws IOException {
         IDATOutputStream ios = new IDATOutputStream(stream, 32768);
-
-        if (metadata.IHDR_interlaceMethod == 1) {
-            for (int i = 0; i < 7; i++) {
-                encodePass(ios, image,
-                           PNGImageReader.adam7XOffset[i],
-                           PNGImageReader.adam7YOffset[i],
-                           PNGImageReader.adam7XSubsampling[i],
-                           PNGImageReader.adam7YSubsampling[i]);
-                if (abortRequested()) {
-                    break;
+        try {
+            if (metadata.IHDR_interlaceMethod == 1) {
+                for (int i = 0; i < 7; i++) {
+                    encodePass(ios, image,
+                               PNGImageReader.adam7XOffset[i],
+                               PNGImageReader.adam7YOffset[i],
+                               PNGImageReader.adam7XSubsampling[i],
+                               PNGImageReader.adam7YSubsampling[i]);
+                    if (abortRequested()) {
+                        break;
+                    }
                 }
+            } else {
+                encodePass(ios, image, 0, 0, 1, 1);
             }
-        } else {
-            encodePass(ios, image, 0, 0, 1, 1);
+        } finally {
+            ios.finish();
         }
-
-        ios.finish();
     }
 
     private void writeIEND() throws IOException {