Updated Branches: refs/heads/flume-1.4 65d3d63ee -> 102c5e07d
FLUME-1765. Add Load Balancing Log4jAppender. (Cameron Gandevia via Hari Shreedharan) Project: http://git-wip-us.apache.org/repos/asf/flume/repo Commit: http://git-wip-us.apache.org/repos/asf/flume/commit/102c5e07 Tree: http://git-wip-us.apache.org/repos/asf/flume/tree/102c5e07 Diff: http://git-wip-us.apache.org/repos/asf/flume/diff/102c5e07 Branch: refs/heads/flume-1.4 Commit: 102c5e07dec17740866315d342afc00c19267569 Parents: 65d3d63 Author: Hari Shreedharan <[email protected]> Authored: Thu Feb 21 23:16:55 2013 -0800 Committer: Hari Shreedharan <[email protected]> Committed: Thu Feb 21 23:18:16 2013 -0800 ---------------------------------------------------------------------- .../log4jappender/LoadBalancingLog4jAppender.java | 153 +++++++++ .../flume/clients/log4jappender/Log4jAppender.java | 3 +- .../TestLoadBalancingLog4jAppender.java | 265 +++++++++++++++ ...lume-loadbalancing-backoff-log4jtest.properties | 21 ++ .../flume-loadbalancing-rnd-log4jtest.properties | 20 ++ .../flume-loadbalancinglog4jtest.properties | 19 + flume-ng-doc/sphinx/FlumeUserGuide.rst | 61 ++++ 7 files changed, 541 insertions(+), 1 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/flume/blob/102c5e07/flume-ng-clients/flume-ng-log4jappender/src/main/java/org/apache/flume/clients/log4jappender/LoadBalancingLog4jAppender.java ---------------------------------------------------------------------- diff --git a/flume-ng-clients/flume-ng-log4jappender/src/main/java/org/apache/flume/clients/log4jappender/LoadBalancingLog4jAppender.java b/flume-ng-clients/flume-ng-log4jappender/src/main/java/org/apache/flume/clients/log4jappender/LoadBalancingLog4jAppender.java new file mode 100644 index 0000000..9fb115e --- /dev/null +++ b/flume-ng-clients/flume-ng-log4jappender/src/main/java/org/apache/flume/clients/log4jappender/LoadBalancingLog4jAppender.java @@ -0,0 +1,153 @@ +/* + * 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.flume.clients.log4jappender; + +import java.util.Properties; + +import org.apache.commons.lang.StringUtils; +import org.apache.flume.FlumeException; +import org.apache.flume.api.RpcClientConfigurationConstants; +import org.apache.flume.api.RpcClientFactory; +import org.apache.flume.api.RpcClientFactory.ClientType; +import org.apache.log4j.helpers.LogLog; + +/** + * + * Appends Log4j Events to an external Flume client which is decribed by the + * Log4j configuration file. The appender takes the following required + * parameters: + * <p> + * <strong>Hosts</strong> : A space separated list of host:port of the first hop + * at which Flume (through an AvroSource) is listening for events. + * </p> + * <p> + * <strong>Selector</strong> : Selection mechanism. Must be either ROUND_ROBIN, + * RANDOM or custom FQDN to class that inherits from LoadBalancingSelector. If + * empty defaults to ROUND_ROBIN + * </p> + * The appender also takes the following optional parameters: + * <p> + * <strong>MaxBackoff</strong> : A long value representing the maximum amount of + * time in milliseconds the Load balancing client will backoff from a node that + * has failed to consume an event + * </p> + * A sample log4j properties file which appends to a source would look like: + * + * <pre> + * <p> + * log4j.appender.out2 = org.apache.flume.clients.log4jappender.LoadBalancingLog4jAppender + * log4j.appender.out2.Hosts = fooflumesource.com:25430 barflumesource.com:25430 + * log4j.appender.out2.Selector = RANDOM + * log4j.logger.org.apache.flume.clients.log4jappender = DEBUG,out2</p> + * </pre> + * <p> + * <pre> + * <p> + * log4j.appender.out2 = org.apache.flume.clients.log4jappender.LoadBalancingLog4jAppender + * log4j.appender.out2.Hosts = fooflumesource.com:25430 barflumesource.com:25430 + * log4j.appender.out2.Selector = ROUND_ROBIN + * log4j.appender.out2.MaxBackoff = 60000 + * log4j.logger.org.apache.flume.clients.log4jappender = DEBUG,out2</p> + * </pre> + * <p> + * <i>Note: Change the last line to the package of the class(es), that will do + * the appending.For example if classes from the package com.bar.foo are + * appending, the last line would be:</i> + * </p> + * + * <pre> + * <p>log4j.logger.com.bar.foo = DEBUG,out2</p> + * </pre> + * + * + */ +public class LoadBalancingLog4jAppender extends Log4jAppender { + + private String hosts; + private String selector; + private String maxBackoff; + + public void setHosts(String hostNames) { + this.hosts = hostNames; + } + + public void setSelector(String selector) { + this.selector = selector; + } + + public void setMaxBackoff(String maxBackoff) { + this.maxBackoff = maxBackoff; + } + + /** + * Activate the options set using <tt>setHosts()</tt>, <tt>setSelector</tt> + * and <tt>setMaxBackoff</tt> + * + * @throws FlumeException + * if the LoadBalancingRpcClient cannot be instantiated. + */ + @Override + public void activateOptions() throws FlumeException { + try { + final Properties properties = getProperties(hosts, selector, maxBackoff); + rpcClient = RpcClientFactory.getInstance(properties); + } catch (FlumeException e) { + String errormsg = "RPC client creation failed! " + e.getMessage(); + LogLog.error(errormsg); + throw e; + } + } + + private Properties getProperties(String hosts, String selector, + String maxBackoff) throws FlumeException { + + if (StringUtils.isEmpty(hosts)) { + throw new IllegalArgumentException("hosts must not be null"); + } + + Properties props = new Properties(); + String[] hostsAndPorts = hosts.split("\\s+"); + StringBuilder names = new StringBuilder(); + for (int i = 0; i < hostsAndPorts.length; i++) { + String hostAndPort = hostsAndPorts[i]; + String name = "h" + i; + props.setProperty(RpcClientConfigurationConstants.CONFIG_HOSTS_PREFIX + name, + hostAndPort); + names.append(name).append(" "); + } + props.put(RpcClientConfigurationConstants.CONFIG_HOSTS, names.toString()); + props.put(RpcClientConfigurationConstants.CONFIG_CLIENT_TYPE, + ClientType.DEFAULT_LOADBALANCE.toString()); + if (!StringUtils.isEmpty(selector)) { + props.put(RpcClientConfigurationConstants.CONFIG_HOST_SELECTOR, selector); + } + + if (!StringUtils.isEmpty(maxBackoff)) { + long millis = Long.parseLong(maxBackoff.trim()); + if (millis <= 0) { + throw new IllegalArgumentException( + "Misconfigured max backoff, value must be greater than 0"); + } + props.put(RpcClientConfigurationConstants.CONFIG_BACKOFF, + String.valueOf(true)); + props.put(RpcClientConfigurationConstants.CONFIG_MAX_BACKOFF, maxBackoff); + } + return props; + } +} http://git-wip-us.apache.org/repos/asf/flume/blob/102c5e07/flume-ng-clients/flume-ng-log4jappender/src/main/java/org/apache/flume/clients/log4jappender/Log4jAppender.java ---------------------------------------------------------------------- diff --git a/flume-ng-clients/flume-ng-log4jappender/src/main/java/org/apache/flume/clients/log4jappender/Log4jAppender.java b/flume-ng-clients/flume-ng-log4jappender/src/main/java/org/apache/flume/clients/log4jappender/Log4jAppender.java index 315a68c..d61f807 100644 --- a/flume-ng-clients/flume-ng-log4jappender/src/main/java/org/apache/flume/clients/log4jappender/Log4jAppender.java +++ b/flume-ng-clients/flume-ng-log4jappender/src/main/java/org/apache/flume/clients/log4jappender/Log4jAppender.java @@ -63,7 +63,8 @@ public class Log4jAppender extends AppenderSkeleton { private String hostname; private int port; - private RpcClient rpcClient = null; + + RpcClient rpcClient = null; /** http://git-wip-us.apache.org/repos/asf/flume/blob/102c5e07/flume-ng-clients/flume-ng-log4jappender/src/test/java/org/apache/flume/clients/log4jappender/TestLoadBalancingLog4jAppender.java ---------------------------------------------------------------------- diff --git a/flume-ng-clients/flume-ng-log4jappender/src/test/java/org/apache/flume/clients/log4jappender/TestLoadBalancingLog4jAppender.java b/flume-ng-clients/flume-ng-log4jappender/src/test/java/org/apache/flume/clients/log4jappender/TestLoadBalancingLog4jAppender.java new file mode 100644 index 0000000..657af67 --- /dev/null +++ b/flume-ng-clients/flume-ng-log4jappender/src/test/java/org/apache/flume/clients/log4jappender/TestLoadBalancingLog4jAppender.java @@ -0,0 +1,265 @@ +/* + * 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.flume.clients.log4jappender; + +import java.io.File; +import java.io.FileReader; +import java.io.IOException; +import java.util.ArrayList; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.Properties; +import java.util.Set; +import java.util.concurrent.atomic.AtomicInteger; + +import junit.framework.Assert; + +import org.apache.flume.Channel; +import org.apache.flume.ChannelSelector; +import org.apache.flume.Context; +import org.apache.flume.Event; +import org.apache.flume.EventDeliveryException; +import org.apache.flume.FlumeException; +import org.apache.flume.Source; +import org.apache.flume.Transaction; +import org.apache.flume.channel.ChannelProcessor; +import org.apache.flume.channel.MemoryChannel; +import org.apache.flume.channel.ReplicatingChannelSelector; +import org.apache.flume.conf.Configurables; +import org.apache.flume.source.AvroSource; +import org.apache.flume.source.avro.AvroFlumeEvent; +import org.apache.flume.source.avro.Status; +import org.apache.log4j.Level; +import org.apache.log4j.LogManager; +import org.apache.log4j.Logger; +import org.apache.log4j.PropertyConfigurator; +import org.junit.After; +import org.junit.Before; +import org.junit.Test; + +import com.google.common.collect.Lists; + +public class TestLoadBalancingLog4jAppender{ + + private final List<CountingAvroSource> sources = Lists.newArrayList(); + private Channel ch; + private ChannelSelector rcs; + private Logger fixture; + + @Before + public void initiate() throws InterruptedException{ + ch = new MemoryChannel(); + Configurables.configure(ch, new Context()); + + List<Channel> channels = new ArrayList<Channel>(); + channels.add(ch); + + rcs = new ReplicatingChannelSelector(); + rcs.setChannels(channels); + } + + @After + public void cleanUp() { + for (Source source : sources) { + source.stop(); + } + } + + @Test + public void testLog4jAppenderRoundRobin() throws IOException { + int numberOfMsgs = 1000; + int expectedPerSource = 500; + File TESTFILE = new File(TestLoadBalancingLog4jAppender.class + .getClassLoader() + .getResource("flume-loadbalancinglog4jtest.properties").getFile()); + startSources(TESTFILE, new int[] { 25430, 25431 }); + + sendAndAssertMessages(numberOfMsgs); + + for (CountingAvroSource source : sources) { + Assert.assertEquals(expectedPerSource, source.appendCount.get()); + } + } + + @Test + public void testLog4jAppenderRandom() throws IOException { + int numberOfMsgs = 1000; + File TESTFILE = new File(TestLoadBalancingLog4jAppender.class + .getClassLoader() + .getResource("flume-loadbalancing-rnd-log4jtest.properties").getFile()); + startSources(TESTFILE, new int[] { 25430, 25431, 25432, 25433, 25434, + 25435, 25436, 25437, 25438, 25439 }); + + sendAndAssertMessages(numberOfMsgs); + + int total = 0; + Set<Integer> counts = new HashSet<Integer>(); + for (CountingAvroSource source : sources) { + total += source.appendCount.intValue(); + counts.add(source.appendCount.intValue()); + } + // We are not testing distribution this is tested in the client + Assert.assertTrue("Very unusual distribution " + counts.size(), counts.size() > 2); + Assert.assertTrue("Missing events", total == numberOfMsgs); + } + + @Test + public void testRandomBackoff() throws Exception { + File TESTFILE = new File(TestLoadBalancingLog4jAppender.class + .getClassLoader() + .getResource("flume-loadbalancing-backoff-log4jtest.properties") + .getFile()); + startSources(TESTFILE, new int[] { 25430, 25431, 25432 }); + + sources.get(0).setFail(); + sources.get(2).setFail(); + + sendAndAssertMessages(50); + + Assert.assertEquals(50, sources.get(1).appendCount.intValue()); + Assert.assertEquals(0, sources.get(0).appendCount.intValue()); + Assert.assertEquals(0, sources.get(2).appendCount.intValue()); + sources.get(0).setOk(); + sources.get(1).setFail(); // s0 should still be backed off + try { + send(1); + // nothing should be able to process right now + Assert.fail("Expected EventDeliveryException"); + } catch (FlumeException e) { + Assert.assertTrue(e.getCause() instanceof EventDeliveryException); + } + Thread.sleep(2500); // wait for s0 to no longer be backed off + + sendAndAssertMessages(50); + + Assert.assertEquals(50, sources.get(0).appendCount.intValue()); + Assert.assertEquals(50, sources.get(1).appendCount.intValue()); + Assert.assertEquals(0, sources.get(2).appendCount.intValue()); + } + + private void send(int numberOfMsgs) throws EventDeliveryException { + for (int count = 0; count < numberOfMsgs; count++) { + int level = count % 5; + String msg = "This is log message number" + String.valueOf(count); + fixture.log(Level.toLevel(level), msg); + } + } + + private void sendAndAssertMessages(int numberOfMsgs) throws IOException { + for (int count = 0; count < numberOfMsgs; count++) { + int level = count % 5; + String msg = "This is log message number" + String.valueOf(count); + fixture.log(Level.toLevel(level), msg); + + Transaction transaction = ch.getTransaction(); + transaction.begin(); + Event event = ch.take(); + Assert.assertNotNull(event); + Assert.assertEquals(new String(event.getBody(), "UTF8"), msg); + + Map<String, String> hdrs = event.getHeaders(); + + Assert.assertNotNull(hdrs.get(Log4jAvroHeaders.TIMESTAMP.toString())); + + Assert.assertEquals(Level.toLevel(level), + Level.toLevel(hdrs.get(Log4jAvroHeaders.LOG_LEVEL.toString()))); + + Assert.assertEquals(fixture.getName(), + hdrs.get(Log4jAvroHeaders.LOGGER_NAME.toString())); + + Assert.assertEquals("UTF8", + hdrs.get(Log4jAvroHeaders.MESSAGE_ENCODING.toString())); + // To confirm on console we actually got the body + System.out.println("Got body: " + new String(event.getBody(), "UTF8")); + transaction.commit(); + transaction.close(); + } + + } + + private void startSources(File log4jProps, int... ports) throws IOException { + for (int port : ports) { + CountingAvroSource source = new CountingAvroSource(port); + Context context = new Context(); + context.put("port", String.valueOf(port)); + context.put("bind", "0.0.0.0"); + Configurables.configure(source, context); + sources.add(source); + source.setChannelProcessor(new ChannelProcessor(rcs)); + } + + for (Source source : sources) { + source.start(); + } + + // The properties file having Avro port info should be loaded only + // after the test begins, else log4j tries to connect to the source + // before the source has started up in the above function, since + // log4j setup is completed before the @Before calls also. + // This will cause the test to fail even before it starts! + + FileReader reader = new FileReader(log4jProps); + Properties props = new Properties(); + props.load(reader); + PropertyConfigurator.configure(props); + fixture = LogManager.getLogger(TestLoadBalancingLog4jAppender.class); + } + + static class CountingAvroSource extends AvroSource { + AtomicInteger appendCount = new AtomicInteger(); + volatile boolean isFail = false; + private final int port2; + + public CountingAvroSource(int port) { + port2 = port; + } + + public void setOk() { + this.isFail = false; + } + + public void setFail() { + this.isFail = true; + } + + @Override + public String getName() { + return "testing..." + port2; + } + + @Override + public Status append(AvroFlumeEvent avroEvent) { + if (isFail) { + return Status.FAILED; + } + appendCount.incrementAndGet(); + return super.append(avroEvent); + } + + @Override + public Status appendBatch(List<AvroFlumeEvent> events) { + if (isFail) { + return Status.FAILED; + } + appendCount.addAndGet(events.size()); + return super.appendBatch(events); + } + } +} http://git-wip-us.apache.org/repos/asf/flume/blob/102c5e07/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancing-backoff-log4jtest.properties ---------------------------------------------------------------------- diff --git a/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancing-backoff-log4jtest.properties b/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancing-backoff-log4jtest.properties new file mode 100644 index 0000000..6e8235e --- /dev/null +++ b/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancing-backoff-log4jtest.properties @@ -0,0 +1,21 @@ +# 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. +log4j.appender.out2 = org.apache.flume.clients.log4jappender.LoadBalancingLog4jAppender +log4j.appender.out2.Hosts = localhost:25430 localhost:25431 localhost:25432 +log4j.appender.out2.Selector = ROUND_ROBIN +log4j.appender.out2.MaxBackoff = 30000 +log4j.logger.org.apache.flume.clients.log4jappender = DEBUG,out2 \ No newline at end of file http://git-wip-us.apache.org/repos/asf/flume/blob/102c5e07/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancing-rnd-log4jtest.properties ---------------------------------------------------------------------- diff --git a/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancing-rnd-log4jtest.properties b/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancing-rnd-log4jtest.properties new file mode 100644 index 0000000..fd43d19 --- /dev/null +++ b/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancing-rnd-log4jtest.properties @@ -0,0 +1,20 @@ +# 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. +log4j.appender.out2 = org.apache.flume.clients.log4jappender.LoadBalancingLog4jAppender +log4j.appender.out2.Hosts = localhost:25430 localhost:25431 localhost:25432 localhost:25433 localhost:25434 localhost:25435 localhost:25436 localhost:25437 localhost:25438 localhost:25439 +log4j.appender.out2.Selector = RANDOM +log4j.logger.org.apache.flume.clients.log4jappender = DEBUG,out2 \ No newline at end of file http://git-wip-us.apache.org/repos/asf/flume/blob/102c5e07/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancinglog4jtest.properties ---------------------------------------------------------------------- diff --git a/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancinglog4jtest.properties b/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancinglog4jtest.properties new file mode 100644 index 0000000..618e504 --- /dev/null +++ b/flume-ng-clients/flume-ng-log4jappender/src/test/resources/flume-loadbalancinglog4jtest.properties @@ -0,0 +1,19 @@ +# 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. +log4j.appender.out2 = org.apache.flume.clients.log4jappender.LoadBalancingLog4jAppender +log4j.appender.out2.Hosts = localhost:25430 localhost:25431 +log4j.logger.org.apache.flume.clients.log4jappender = DEBUG,out2 \ No newline at end of file http://git-wip-us.apache.org/repos/asf/flume/blob/102c5e07/flume-ng-doc/sphinx/FlumeUserGuide.rst ---------------------------------------------------------------------- diff --git a/flume-ng-doc/sphinx/FlumeUserGuide.rst b/flume-ng-doc/sphinx/FlumeUserGuide.rst index 8eb3734..8a4ecda 100644 --- a/flume-ng-doc/sphinx/FlumeUserGuide.rst +++ b/flume-ng-doc/sphinx/FlumeUserGuide.rst @@ -2491,6 +2491,67 @@ Sample log4j.properties file: log4j.logger.org.example.MyClass = DEBUG,flume #... +Load Balancing Log4J Appender +============================= + +Appends Log4j events to a list of flume agent's avro source. A client using this +appender must have the flume-ng-sdk in the classpath (eg, +flume-ng-sdk-1.4.0-SNAPSHOT.jar). This appender supports a round-robin and random +scheme for performing the load balancing. It also supports a configurable backoff +timeout so that down agents are removed temporarily from the set of hosts +Required properties are in **bold**. + +============= =========== ========================================================================== +Property Name Default Description +============= =========== ========================================================================== +**Hosts** -- A space separated list of host:port + at which Flume (through an AvroSource) is listening for events +Selector ROUND_ROBIN Selection mechanism. Must be either ROUND_ROBIN, + RANDOM or custom FQDN to class that inherits from LoadBalancingSelector. +MaxBackoff -- A long value representing the maximum amount of time in milliseconds + the Load balancing client will backoff from a node that has failed to + consume an event. Defaults to no backoff +============= =========== ========================================================================== + + +Sample log4j.properties file configured using defaults: + +.. code-block:: properties + + #... + log4j.appender.out2 = org.apache.flume.clients.log4jappender.LoadBalancingLog4jAppender + log4j.appender.out2.Hosts = localhost:25430 localhost:25431 + + # configure a class's logger to output to the flume appender + log4j.logger.org.example.MyClass = DEBUG,flume + #... + +Sample log4j.properties file configured using RANDOM load balancing: + +.. code-block:: properties + + #... + log4j.appender.out2 = org.apache.flume.clients.log4jappender.LoadBalancingLog4jAppender + log4j.appender.out2.Hosts = localhost:25430 localhost:25431 + log4j.appender.out2.Selector = RANDOM + + # configure a class's logger to output to the flume appender + log4j.logger.org.example.MyClass = DEBUG,flume + #... + +Sample log4j.properties file configured using backoff: + +.. code-block:: properties + + #... + log4j.appender.out2 = org.apache.flume.clients.log4jappender.LoadBalancingLog4jAppender + log4j.appender.out2.Hosts = localhost:25430 localhost:25431 localhost:25432 + log4j.appender.out2.Selector = ROUND_ROBIN + log4j.appender.out2.MaxBackoff = 30000 + + # configure a class's logger to output to the flume appender + log4j.logger.org.example.MyClass = DEBUG,flume + #... 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