From 5dcc8693d7d1ab81e3d6e6583a3918a3b6003bad Mon Sep 17 00:00:00 2001 From: Roberto Tyley Date: Tue, 25 Dec 2012 09:10:51 +0000 Subject: [PATCH] Fix concurrent creation of fan-out object directories If multiple threads attempted to insert loose objects into the same new fan-out directory, the creation of that directory was subject to a race condition that could lead to an unnecessary IOException being thrown - because an inserter could not 'create' a directory that had just been generated by a different thread. All we require is that the directory does indeed *exist*, so not being able to _create_ it is not actually a fatal problem. Setting 'skipExisting' to 'true' on the call to mkdir() fixes the issue. I found this issue as a real world occurrence while working on The BFG Repo Cleaner (https://github.com/rtyley/bfg-repo-cleaner), a tool which concurrently performs a lot of object creation. In order to demonstrate the problem here I've added a small test case which reliably reproduces the issue on the few different hardware systems I've tried. The error thrown when the race-condition arises is this: java.io.IOException: Creating directory /home/roberto/repo.git/objects/e6 failed at org.eclipse.jgit.util.FileUtils.mkdir(FileUtils.java:182) at org.eclipse.jgit.storage.file.ObjectDirectory.insertUnpackedObject(ObjectDirectory.java:590) at org.eclipse.jgit.storage.file.ObjectDirectoryInserter.insertOneObject(ObjectDirectoryInserter.java:113) at org.eclipse.jgit.storage.file.ObjectDirectoryInserter.insert(ObjectDirectoryInserter.java:91) at org.eclipse.jgit.lib.ObjectInserter.insert(ObjectInserter.java:329) Change-Id: I88eac49bc600c56ba9ad290e6133d8a7113125ab --- .../storage/file/ObjectDirectoryTest.java | 77 +++++++++++++++++++ .../jgit/storage/file/ObjectDirectory.java | 2 +- 2 files changed, 78 insertions(+), 1 deletion(-) create mode 100644 org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/ObjectDirectoryTest.java diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/ObjectDirectoryTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/ObjectDirectoryTest.java new file mode 100644 index 000000000..52c9ec705 --- /dev/null +++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/ObjectDirectoryTest.java @@ -0,0 +1,77 @@ +/* + * Copyright (C) 2012, Roberto Tyley + * + * This program and the accompanying materials are made available + * under the terms of the Eclipse Distribution License v1.0 which + * accompanies this distribution, is reproduced below, and is + * available at http://www.eclipse.org/org/documents/edl-v10.php + * + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or + * without modification, are permitted provided that the following + * conditions are met: + * + * - Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * - Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials provided + * with the distribution. + * + * - Neither the name of the Eclipse Foundation, Inc. nor the + * names of its contributors may be used to endorse or promote + * products derived from this software without specific prior + * written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND + * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, + * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER + * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF + * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +package org.eclipse.jgit.storage.file; + +import org.eclipse.jgit.lib.Constants; +import org.eclipse.jgit.lib.ObjectId; +import org.eclipse.jgit.lib.RepositoryTestCase; +import org.junit.Test; + +import java.util.*; +import java.util.concurrent.*; + +public class ObjectDirectoryTest extends RepositoryTestCase { + + @Test + public void testConcurrentInsertionOfBlobsToTheSameNewFanOutDirectory() + throws Exception { + ExecutorService e = Executors.newCachedThreadPool(); + for (int i=0; i < 100; ++i) { + ObjectDirectory db = createBareRepository().getObjectDatabase(); + for (Future f : e.invokeAll(blobInsertersForTheSameFanOutDir(db))) { + f.get(); + } + } + } + + private Collection> blobInsertersForTheSameFanOutDir( + final ObjectDirectory db) { + Callable callable = new Callable() { + public ObjectId call() throws Exception { + return db.newInserter().insert(Constants.OBJ_BLOB, new byte[0]); + } + }; + return Collections.nCopies(4, callable); + } + +} diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/ObjectDirectory.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/ObjectDirectory.java index 4d196fbf4..22ef45df6 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/ObjectDirectory.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/ObjectDirectory.java @@ -577,7 +577,7 @@ public class ObjectDirectory extends FileObjectDatabase { // directories are always lazily created. Note that we // try the rename first as the directory likely does exist. // - FileUtils.mkdir(dst.getParentFile()); + FileUtils.mkdir(dst.getParentFile(), true); if (tmp.renameTo(dst)) { dst.setReadOnly(); unpackedObjectCache.add(id);