Suspected regression: fix for 6735255 causes delay in GC of ZipFile InputStreams, increase in heap demand
Neil Richards
neil.richards at ngmr.net
Fri Apr 1 16:42:57 UTC 2011
On Wed, 2011-03-30 at 13:31 -0700, Xueming Shen wrote:
> Isn't it true that when the finalize()->close() gets invoked, there
> should be no strong reference anywhere else that you can use to invoke
> close() in other thread?
It's true that once finalize() has been called, there can't be another
explicit call to close().
However, if close() is explicitly called first, it will be called again
when finalize() calls it, so one still wants the update to 'isClosed' to
be seen by the finalizer thread (in this case).
> ZipFileInputStream class has to sync on ZipFile.this, the read/close()
> methods are accessing the underlying/shared bits of the ZipFile. For
> ZipFileInflaterInputStream.close() case, even we want to make sure the
> isClose is synced, I would prefer to see a "local" lock, maybe simply
> make close() synchronized is better?
After assessing it again, I tend to agree - synchronizing on the ZFIIS
(instead of the ZipFile) now looks to me to be safe because it does not
do anything which synchronizes on the ZipFile object.
(Note that if it _did_ cause such synchronization, it would risk
deadlock with the code in ZipFile's close() method, which is
synchronized on itself when it calls close() on each remaining ZFIIS.
It's the difference in the order of acquiring the monitors that would
cause the potential for deadlock).
As it is, both close() methods synchronize on the 'inflaters' object
within their respective synchronized blocks, but that does not risk
deadlock.
Please find below an updated changeset below, containing the suggested
change to synchronization.
Thanks once again for your suggestions,
Neil
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IBM email: neil_richards at uk.ibm.com
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# HG changeset patch
# User Neil Richards <neil.richards at ngmr.net>, <neil_richards at uk.ibm.com>
# Date 1300289208 0
# Branch zip-heap
# Node ID 4aa4844cd3b9ae747ad736469134a8828ebeb652
# Parent 554adcfb615e63e62af530b1c10fcf7813a75b26
7031076: Retained ZipFile InputStreams increase heap demand
Summary: Allow unreferenced ZipFile InputStreams to be finalized, GC'd
Contributed-by: <neil.richards at ngmr.net>
diff --git a/src/share/classes/java/util/zip/ZipFile.java b/src/share/classes/java/util/zip/ZipFile.java
--- a/src/share/classes/java/util/zip/ZipFile.java
+++ b/src/share/classes/java/util/zip/ZipFile.java
@@ -30,11 +30,14 @@
import java.io.IOException;
import java.io.EOFException;
import java.io.File;
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
import java.nio.charset.Charset;
import java.util.Vector;
import java.util.Enumeration;
import java.util.Set;
import java.util.HashSet;
+import java.util.Iterator;
import java.util.NoSuchElementException;
import java.security.AccessController;
import sun.security.action.GetPropertyAction;
@@ -315,7 +318,16 @@
private static native void freeEntry(long jzfile, long jzentry);
// the outstanding inputstreams that need to be closed.
- private Set<InputStream> streams = new HashSet<>();
+ private final Set<WeakReference<InputStream>> streams = new HashSet<>();
+ private final ReferenceQueue<? super InputStream> staleStreamQueue =
+ new ReferenceQueue<>();
+
+ private void clearStaleStreams() {
+ Object staleStream;
+ while (null != (staleStream = staleStreamQueue.poll())) {
+ streams.remove(staleStream);
+ }
+ }
/**
* Returns an input stream for reading the contents of the specified
@@ -339,6 +351,7 @@
ZipFileInputStream in = null;
synchronized (this) {
ensureOpen();
+ clearStaleStreams();
if (!zc.isUTF8() && (entry.flag & EFS) != 0) {
jzentry = getEntry(jzfile, zc.getBytesUTF8(entry.name), false);
} else {
@@ -351,51 +364,19 @@
switch (getEntryMethod(jzentry)) {
case STORED:
- streams.add(in);
+ streams.add(
+ new WeakReference<InputStream>(in, staleStreamQueue));
return in;
case DEFLATED:
- final ZipFileInputStream zfin = in;
// MORE: Compute good size for inflater stream:
long size = getEntrySize(jzentry) + 2; // Inflater likes a bit of slack
if (size > 65536) size = 8192;
if (size <= 0) size = 4096;
- InputStream is = new InflaterInputStream(zfin, getInflater(), (int)size) {
- private boolean isClosed = false;
-
- public void close() throws IOException {
- if (!isClosed) {
- super.close();
- releaseInflater(inf);
- isClosed = true;
- }
- }
- // Override fill() method to provide an extra "dummy" byte
- // at the end of the input stream. This is required when
- // using the "nowrap" Inflater option.
- protected void fill() throws IOException {
- if (eof) {
- throw new EOFException(
- "Unexpected end of ZLIB input stream");
- }
- len = this.in.read(buf, 0, buf.length);
- if (len == -1) {
- buf[0] = 0;
- len = 1;
- eof = true;
- }
- inf.setInput(buf, 0, len);
- }
- private boolean eof;
-
- public int available() throws IOException {
- if (isClosed)
- return 0;
- long avail = zfin.size() - inf.getBytesWritten();
- return avail > (long) Integer.MAX_VALUE ?
- Integer.MAX_VALUE : (int) avail;
- }
- };
- streams.add(is);
+ InputStream is =
+ new ZipFileInflaterInputStream(in, getInflater(),
+ (int)size);
+ streams.add(
+ new WeakReference<InputStream>(is, staleStreamQueue));
return is;
default:
throw new ZipException("invalid compression method");
@@ -403,6 +384,56 @@
}
}
+ private class ZipFileInflaterInputStream extends InflaterInputStream {
+ private boolean isClosed = false;
+ private boolean eof = false;
+ private final ZipFileInputStream zfin;
+ private boolean inFinalizer = false;
+
+ ZipFileInflaterInputStream(ZipFileInputStream zfin, Inflater inf,
+ int size) {
+ super(zfin, inf, size);
+ this.zfin = zfin;
+ }
+
+ public synchronized void close() throws IOException {
+ if (!isClosed) {
+ super.close();
+ if (false == inFinalizer)
+ releaseInflater(inf);
+ isClosed = true;
+ }
+ }
+ // Override fill() method to provide an extra "dummy" byte
+ // at the end of the input stream. This is required when
+ // using the "nowrap" Inflater option.
+ protected void fill() throws IOException {
+ if (eof) {
+ throw new EOFException("Unexpected end of ZLIB input stream");
+ }
+ len = in.read(buf, 0, buf.length);
+ if (len == -1) {
+ buf[0] = 0;
+ len = 1;
+ eof = true;
+ }
+ inf.setInput(buf, 0, len);
+ }
+
+ public int available() throws IOException {
+ if (isClosed)
+ return 0;
+ long avail = zfin.size() - inf.getBytesWritten();
+ return (avail > (long) Integer.MAX_VALUE ?
+ Integer.MAX_VALUE : (int) avail);
+ }
+
+ protected void finalize() throws IOException {
+ inFinalizer = true;
+ close();
+ }
+ }
+
/*
* Gets an inflater from the list of available inflaters or allocates
* a new one.
@@ -543,11 +574,14 @@
synchronized (this) {
closeRequested = true;
- if (streams.size() !=0) {
- Set<InputStream> copy = streams;
- streams = new HashSet<>();
- for (InputStream is: copy)
+ Iterator<WeakReference<InputStream>> streamsIterator =
+ streams.iterator();
+ while (streamsIterator.hasNext()) {
+ InputStream is = streamsIterator.next().get();
+ if (null != is) {
is.close();
+ }
+ streamsIterator.remove();
}
if (jzfile != 0) {
@@ -684,9 +718,12 @@
freeEntry(ZipFile.this.jzfile, jzentry);
jzentry = 0;
}
- streams.remove(this);
}
}
+
+ protected void finalize() {
+ close();
+ }
}
diff --git a/test/java/util/zip/ZipFile/ClearStaleZipFileInputStreams.java b/test/java/util/zip/ZipFile/ClearStaleZipFileInputStreams.java
new file mode 100644
--- /dev/null
+++ b/test/java/util/zip/ZipFile/ClearStaleZipFileInputStreams.java
@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2011 Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * Portions Copyright (c) 2011 IBM Corporation
+ */
+
+/*
+ * @test
+ * @bug 7031076
+ * @summary Allow stale InputStreams from ZipFiles to be GC'd
+ * @author Neil Richards <neil.richards at ngmr.net>, <neil_richards at uk.ibm.com>
+ */
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.InputStream;
+import java.util.Enumeration;
+import java.util.HashSet;
+import java.util.Random;
+import java.util.Set;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+import java.util.zip.ZipOutputStream;
+
+public class ClearStaleZipFileInputStreams {
+ private static final int ZIP_ENTRY_NUM = 5;
+
+ private static final byte[][] data;
+
+ static {
+ data = new byte[ZIP_ENTRY_NUM][];
+ Random r = new Random();
+ for (int i = 0; i < ZIP_ENTRY_NUM; i++) {
+ data[i] = new byte[1000];
+ r.nextBytes(data[i]);
+ }
+ }
+
+ private static File createTestFile(int compression) throws Exception {
+ File tempZipFile =
+ File.createTempFile("test-data" + compression, ".zip");
+ tempZipFile.deleteOnExit();
+
+ ZipOutputStream zos =
+ new ZipOutputStream(new FileOutputStream(tempZipFile));
+ zos.setLevel(compression);
+
+ try {
+ for (int i = 0; i < ZIP_ENTRY_NUM; i++) {
+ String text = "Entry" + i;
+ ZipEntry entry = new ZipEntry(text);
+ zos.putNextEntry(entry);
+ try {
+ zos.write(data[i], 0, data[i].length);
+ } finally {
+ zos.closeEntry();
+ }
+ }
+ } finally {
+ zos.close();
+ }
+
+ return tempZipFile;
+ }
+
+ private static void startGcInducingThread(final int sleepMillis) {
+ final Thread gcInducingThread = new Thread() {
+ public void run() {
+ while (true) {
+ System.gc();
+ try {
+ Thread.sleep(sleepMillis);
+ } catch (InterruptedException e) { }
+ }
+ }
+ };
+
+ gcInducingThread.setDaemon(true);
+ gcInducingThread.start();
+ }
+
+ public static void main(String[] args) throws Exception {
+ startGcInducingThread(500);
+ runTest(ZipOutputStream.DEFLATED);
+ runTest(ZipOutputStream.STORED);
+ }
+
+ private static void runTest(int compression) throws Exception {
+ ReferenceQueue<InputStream> rq = new ReferenceQueue<>();
+
+ System.out.println("Testing with a zip file with compression level = "
+ + compression);
+ File f = createTestFile(compression);
+ try {
+ ZipFile zf = new ZipFile(f);
+ try {
+ Set<Object> refSet = createTransientInputStreams(zf, rq);
+
+ System.out.println("Waiting for 'stale' input streams from ZipFile to be GC'd ...");
+ System.out.println("(The test will hang on failure)");
+ while (false == refSet.isEmpty()) {
+ refSet.remove(rq.remove());
+ }
+ System.out.println("Test PASSED.");
+ System.out.println();
+ } finally {
+ zf.close();
+ }
+ } finally {
+ f.delete();
+ }
+ }
+
+ private static Set<Object> createTransientInputStreams(ZipFile zf,
+ ReferenceQueue<InputStream> rq) throws Exception {
+ Enumeration<? extends ZipEntry> zfe = zf.entries();
+ Set<Object> refSet = new HashSet<>();
+
+ while (zfe.hasMoreElements()) {
+ InputStream is = zf.getInputStream(zfe.nextElement());
+ refSet.add(new WeakReference<InputStream>(is, rq));
+ }
+
+ return refSet;
+ }
+}
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