Allow to bypass journal for writes

bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/Bookie.java

@@ -150,6 +150,8 @@ public class Bookie extends BookieCriticalThread {
 
     private final ByteBufAllocator allocator;
 
+    private final boolean writeDataToJournal;
+
     @StatsDoc(
             name = JOURNAL_MEMORY_MAX,
             help = "The max amount of memory in bytes that can be used by the bookie journal"
@@ -721,6 +723,7 @@ public Bookie(ServerConfiguration conf, StatsLogger statsLogger,
         this.ledgerDirsManager = createLedgerDirsManager(conf, diskChecker, statsLogger.scope(LD_LEDGER_SCOPE));
         this.indexDirsManager = createIndexDirsManager(conf, diskChecker, statsLogger.scope(LD_INDEX_SCOPE),
                                                        this.ledgerDirsManager);
+        this.writeDataToJournal = conf.getJournalWriteData();
         this.allocator = allocator;
 
         // instantiate zookeeper client to initialize ledger manager
@@ -1338,6 +1341,11 @@ private void addEntryInternal(LedgerDescriptor handle, ByteBuf entry,
             }
         }
 
+        if (!writeDataToJournal) {
+            cb.writeComplete(0, ledgerId, entryId, null, ctx);
+            return;
+        }
+
         if (LOG.isTraceEnabled()) {
             LOG.trace("Adding {}@{}", entryId, ledgerId);
         }

bookkeeper-server/src/main/java/org/apache/bookkeeper/conf/ServerConfiguration.java

@@ -131,6 +131,7 @@ public class ServerConfiguration extends AbstractConfiguration<ServerConfigurati
     protected static final String MAX_JOURNAL_SIZE = "journalMaxSizeMB";
     protected static final String MAX_BACKUP_JOURNALS = "journalMaxBackups";
     protected static final String JOURNAL_SYNC_DATA = "journalSyncData";
+    protected static final String JOURNAL_WRITE_DATA = "journalWriteData";
     protected static final String JOURNAL_ADAPTIVE_GROUP_WRITES = "journalAdaptiveGroupWrites";
     protected static final String JOURNAL_MAX_GROUP_WAIT_MSEC = "journalMaxGroupWaitMSec";
     protected static final String JOURNAL_BUFFERED_WRITES_THRESHOLD = "journalBufferedWritesThreshold";
@@ -2107,6 +2108,29 @@ public boolean getJournalSyncData() {
         return getBoolean(JOURNAL_SYNC_DATA, true);
     }
 
+    /**
+     * Should the data be written to journal before acknowledgment.
+     *
+     * <p>Default is true
+     *
+     * @return
+     */
+    public boolean getJournalWriteData() {
+        return getBoolean(JOURNAL_WRITE_DATA, true);
+    }
+
+    /**
+     * Should the data be written to journal before acknowledgment.
+     *
+     * <p>Default is true
+     *
+     * @return
+     */
+    public ServerConfiguration setJournalWriteData(boolean journalWriteData) {
+        setProperty(JOURNAL_WRITE_DATA, journalWriteData);
+        return this;
+    }
+
     /**
      * Enable or disable journal syncs.
      *

bookkeeper-server/src/test/java/org/apache/bookkeeper/bookie/BookieJournalBypassTest.java

@@ -0,0 +1,106 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+package org.apache.bookkeeper.bookie;
+
+import static org.junit.Assert.assertEquals;
+import lombok.Cleanup;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.bookkeeper.client.BookKeeper;
+import org.apache.bookkeeper.client.api.WriteHandle;
+import org.apache.bookkeeper.conf.ClientConfiguration;
+import org.apache.bookkeeper.conf.ServerConfiguration;
+import org.apache.bookkeeper.proto.BookieServer;
+import org.apache.bookkeeper.test.BookKeeperClusterTestCase;
+import org.junit.Test;
+
+/**
+ * Tests that we're skipping journal when it's configured to do so.
+ */
+@Slf4j
+public class BookieJournalBypassTest extends BookKeeperClusterTestCase {
+
+    private int bookieIdx = 0;
+
+    public BookieJournalBypassTest() {
+        super(2);
+    }
+
+    @Override
+    protected BookieServer startBookie(ServerConfiguration conf) throws Exception {
+        if (bookieIdx++ == 0) {
+            // First bookie will have the journal disabled
+            conf.setJournalWriteData(false);
+        }
+        return super.startBookie(conf);
+    }
+
+    @Test
+    public void testJournalBypass() throws Exception {
+        ClientConfiguration conf = new ClientConfiguration(baseClientConf);
+
+        Journal journal0 = bs.get(0).getBookie().journals.get(0);
+        LedgerStorage ls0 = bs.get(0).getBookie().getLedgerStorage();
+
+        Journal journal1 = bs.get(1).getBookie().journals.get(0);
+        LedgerStorage ls1 = bs.get(1).getBookie().getLedgerStorage();
+
+        ls0.flush();
+        ls1.flush();
+
+        long bk0OffsetBefore = journal0.getLastLogMark().getCurMark().getLogFileOffset();
+        long bk1OffsetBefore = journal1.getLastLogMark().getCurMark().getLogFileOffset();
+
+        writeEntries(conf);
+        ls0.flush();
+        ls1.flush();
+
+        long bk0OffsetAfter = journal0.getLastLogMark().getCurMark().getLogFileOffset();
+        long bk1OffsetAfter = journal1.getLastLogMark().getCurMark().getLogFileOffset();
+
+        int flushDelta = 10 * 1024;
+        int dataSize = 10 * 1024 * 1024;
+
+        // Offset for journal-0 will be very close to previous point, just few KBs when flushing
+        assertEquals(bk0OffsetBefore, bk0OffsetAfter, flushDelta);
+
+        // Offset for journal-0 should have changed with the data size
+        assertEquals(bk1OffsetBefore + dataSize, bk1OffsetAfter, flushDelta);
+    }
+
+    private void writeEntries(ClientConfiguration conf)
+            throws Exception {
+        @Cleanup
+        BookKeeper bkc = new BookKeeper(conf);
+
+        @Cleanup
+        WriteHandle wh = bkc.newCreateLedgerOp()
+                .withEnsembleSize(2)
+                .withWriteQuorumSize(2)
+                .withAckQuorumSize(2)
+                .withPassword("".getBytes())
+                .execute()
+                .join();
+
+        for (int i = 0; i < 10; i++) {
+            wh.append(new byte[1024 * 1024]);
+        }
+    }
+}

conf/bk_server.conf

@@ -326,6 +326,14 @@ journalDirectories=/tmp/bk-txn
 # Should we remove pages from page cache after force write
 # journalRemoveFromPageCache=true
 
+# Should the data be written on journal.
+# By default, data is written on journal for durability of writes.
+# Beware: while disabling data journaling in the Bookie journal might improve the bookie write performance, it will also
+# introduce the possibility of data loss. With no journal, the write operations are passed to the storage engine
+# and then acknowledged. In case of power failure, the affected bookie might lose the unflushed data. If the ledger
+# is replicated to multiple bookies, the chances of data loss are reduced though still present.
+# journalWriteData=true
+
 # Should the data be fsynced on journal before acknowledgment.
 # By default, data sync is enabled to guarantee durability of writes.
 # Beware: while disabling data sync in the Bookie journal might improve the bookie write performance, it will also