8282947: JFR: Dump on shutdown live-locks in some conditions

Reviewed-by: mgronlun
This commit is contained in:
Erik Gahlin 2022-05-27 13:00:02 +00:00
parent f2bc447659
commit 63eb0b7e86
3 changed files with 65 additions and 4 deletions
src/jdk.jfr/share/classes/jdk/jfr/internal
test/jdk/jdk/jfr/api/recording/dump

@ -96,10 +96,13 @@ final class ChunksChannel implements ReadableByteChannel {
assert current != null;
long rem = current.getSize();
while (rem > 0) {
long n = Math.min(rem, 1024 * 1024);
long w = out.transferFrom(channel, pos, n);
// Prevent endless loop
if (w == 0) {
return out.size();
}
pos += w;
rem -= w;
}
@ -111,7 +114,7 @@ final class ChunksChannel implements ReadableByteChannel {
current = null;
}
if (!nextChannel()) {
return pos;
return out.size();
}
}
}

@ -713,8 +713,12 @@ public final class PlatformRecording implements AutoCloseable {
synchronized (recorder) {
userPath.doPrivilegedIO(() -> {
try (ChunksChannel cc = new ChunksChannel(chunks); FileChannel fc = FileChannel.open(userPath.getReal(), StandardOpenOption.WRITE, StandardOpenOption.APPEND)) {
cc.transferTo(fc);
fc.force(true);
long bytes = cc.transferTo(fc);
Logger.log(LogTag.JFR, LogLevel.INFO, "Transferred " + bytes + " bytes from the disk repository");
// No need to force if no data was transferred, which avoids IOException when device is /dev/null
if (bytes != 0) {
fc.force(true);
}
}
return null;
});

@ -0,0 +1,54 @@
/*
* Copyright (c) 2022, 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.
*/
package jdk.jfr.api.recording.dump;
import java.nio.file.Path;
import jdk.jfr.Recording;
/**
* @test
* @summary Tests that it's possible to dump to /dev/null without a livelock
* @key jfr
* @requires vm.hasJFR
* @library /test/lib
* @run main/othervm -Xlog:jfr jdk.jfr.api.recording.dump.TestDumpDevNull
*/
public class TestDumpDevNull {
public static void main(String[] args) throws Exception {
try (Recording r1 = new Recording()) {
r1.setDestination(Path.of("/dev/null"));
r1.start();
// Force a chunk rotation which ensures that jdk.jfr.internal.ChunkChannel
// invokes FileChannel::transferFrom(ReadableByteChannel, position, count) twice.
// FileChannel will return 0 the second time because position exceeds
// FileChannel::size(), which is always 0 for /dev/null
// Without proper handling of return value 0, the ChunkChannel will spin indefinitely.
try (Recording r2 = new Recording()) {
r2.start();
}
}
}
}