001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache license, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the license for the specific language governing permissions and 015 * limitations under the license. 016 */ 017 package org.apache.logging.log4j.core.async; 018 019 import java.util.Map; 020 import java.util.concurrent.ExecutorService; 021 import java.util.concurrent.Executors; 022 023 import org.apache.logging.log4j.Level; 024 import org.apache.logging.log4j.Marker; 025 import org.apache.logging.log4j.ThreadContext; 026 import org.apache.logging.log4j.core.Logger; 027 import org.apache.logging.log4j.core.LoggerContext; 028 import org.apache.logging.log4j.core.config.Property; 029 import org.apache.logging.log4j.core.impl.Log4jLogEvent; 030 import org.apache.logging.log4j.core.jmx.RingBufferAdmin; 031 import org.apache.logging.log4j.core.util.Clock; 032 import org.apache.logging.log4j.core.util.ClockFactory; 033 import org.apache.logging.log4j.core.util.Loader; 034 import org.apache.logging.log4j.message.Message; 035 import org.apache.logging.log4j.message.MessageFactory; 036 import org.apache.logging.log4j.status.StatusLogger; 037 038 import com.lmax.disruptor.BlockingWaitStrategy; 039 import com.lmax.disruptor.ExceptionHandler; 040 import com.lmax.disruptor.RingBuffer; 041 import com.lmax.disruptor.SleepingWaitStrategy; 042 import com.lmax.disruptor.WaitStrategy; 043 import com.lmax.disruptor.YieldingWaitStrategy; 044 import com.lmax.disruptor.dsl.Disruptor; 045 import com.lmax.disruptor.dsl.ProducerType; 046 import com.lmax.disruptor.util.Util; 047 048 /** 049 * AsyncLogger is a logger designed for high throughput and low latency logging. 050 * It does not perform any I/O in the calling (application) thread, but instead 051 * hands off the work to another thread as soon as possible. The actual logging 052 * is performed in the background thread. It uses the LMAX Disruptor library for 053 * inter-thread communication. (<a 054 * href="http://lmax-exchange.github.com/disruptor/" 055 * >http://lmax-exchange.github.com/disruptor/</a>) 056 * <p> 057 * To use AsyncLogger, specify the System property 058 * {@code -DLog4jContextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector} 059 * before you obtain a Logger, and all Loggers returned by LogManager.getLogger 060 * will be AsyncLoggers. 061 * <p> 062 * Note that for performance reasons, this logger does not include source 063 * location by default. You need to specify {@code includeLocation="true"} in 064 * the configuration or any %class, %location or %line conversion patterns in 065 * your log4j.xml configuration will produce either a "?" character or no output 066 * at all. 067 * <p> 068 * For best performance, use AsyncLogger with the RandomAccessFileAppender or 069 * RollingRandomAccessFileAppender, with immediateFlush=false. These appenders 070 * have built-in support for the batching mechanism used by the Disruptor 071 * library, and they will flush to disk at the end of each batch. This means 072 * that even with immediateFlush=false, there will never be any items left in 073 * the buffer; all log events will all be written to disk in a very efficient 074 * manner. 075 */ 076 public class AsyncLogger extends Logger { 077 private static final long serialVersionUID = 1L; 078 private static final int SLEEP_MILLIS_BETWEEN_DRAIN_ATTEMPTS = 50; 079 private static final int MAX_DRAIN_ATTEMPTS_BEFORE_SHUTDOWN = 200; 080 private static final int RINGBUFFER_MIN_SIZE = 128; 081 private static final int RINGBUFFER_DEFAULT_SIZE = 256 * 1024; 082 private static final StatusLogger LOGGER = StatusLogger.getLogger(); 083 private static final ThreadNameStrategy THREAD_NAME_STRATEGY = ThreadNameStrategy.create(); 084 private static final ThreadLocal<Info> threadlocalInfo = new ThreadLocal<Info>(); 085 086 static enum ThreadNameStrategy { // LOG4J2-467 087 CACHED { 088 @Override 089 public String getThreadName(final Info info) { 090 return info.cachedThreadName; 091 } 092 }, 093 UNCACHED { 094 @Override 095 public String getThreadName(final Info info) { 096 return Thread.currentThread().getName(); 097 } 098 }; 099 abstract String getThreadName(Info info); 100 101 static ThreadNameStrategy create() { 102 final String name = System.getProperty("AsyncLogger.ThreadNameStrategy", CACHED.name()); 103 try { 104 return ThreadNameStrategy.valueOf(name); 105 } catch (final Exception ex) { 106 LOGGER.debug("Using AsyncLogger.ThreadNameStrategy.CACHED: '{}' not valid: {}", name, ex.toString()); 107 return CACHED; 108 } 109 } 110 } 111 private static volatile Disruptor<RingBufferLogEvent> disruptor; 112 private static final Clock clock = ClockFactory.getClock(); 113 114 private static final ExecutorService executor = Executors 115 .newSingleThreadExecutor(new DaemonThreadFactory("AsyncLogger-")); 116 117 static { 118 initInfoForExecutorThread(); 119 LOGGER.debug("AsyncLogger.ThreadNameStrategy={}", THREAD_NAME_STRATEGY); 120 final int ringBufferSize = calculateRingBufferSize(); 121 122 final WaitStrategy waitStrategy = createWaitStrategy(); 123 disruptor = new Disruptor<RingBufferLogEvent>(RingBufferLogEvent.FACTORY, ringBufferSize, executor, 124 ProducerType.MULTI, waitStrategy); 125 disruptor.handleExceptionsWith(getExceptionHandler()); 126 disruptor.handleEventsWith(new RingBufferLogEventHandler()); 127 128 LOGGER.debug("Starting AsyncLogger disruptor with ringbuffer size {}...", disruptor.getRingBuffer() 129 .getBufferSize()); 130 disruptor.start(); 131 } 132 133 private static int calculateRingBufferSize() { 134 int ringBufferSize = RINGBUFFER_DEFAULT_SIZE; 135 final String userPreferredRBSize = System.getProperty("AsyncLogger.RingBufferSize", 136 String.valueOf(ringBufferSize)); 137 try { 138 int size = Integer.parseInt(userPreferredRBSize); 139 if (size < RINGBUFFER_MIN_SIZE) { 140 size = RINGBUFFER_MIN_SIZE; 141 LOGGER.warn("Invalid RingBufferSize {}, using minimum size {}.", userPreferredRBSize, 142 RINGBUFFER_MIN_SIZE); 143 } 144 ringBufferSize = size; 145 } catch (final Exception ex) { 146 LOGGER.warn("Invalid RingBufferSize {}, using default size {}.", userPreferredRBSize, ringBufferSize); 147 } 148 return Util.ceilingNextPowerOfTwo(ringBufferSize); 149 } 150 151 /** 152 * Initialize an {@code Info} object that is threadlocal to the consumer/appender thread. 153 * This Info object uniquely has attribute {@code isAppenderThread} set to {@code true}. 154 * All other Info objects will have this attribute set to {@code false}. 155 * This allows us to detect Logger.log() calls initiated from the appender thread, 156 * which may cause deadlock when the RingBuffer is full. (LOG4J2-471) 157 */ 158 private static void initInfoForExecutorThread() { 159 executor.submit(new Runnable(){ 160 @Override 161 public void run() { 162 final boolean isAppenderThread = true; 163 final Info info = new Info(new RingBufferLogEventTranslator(), // 164 Thread.currentThread().getName(), isAppenderThread); 165 threadlocalInfo.set(info); 166 } 167 }); 168 } 169 170 private static WaitStrategy createWaitStrategy() { 171 final String strategy = System.getProperty("AsyncLogger.WaitStrategy"); 172 LOGGER.debug("property AsyncLogger.WaitStrategy={}", strategy); 173 if ("Sleep".equals(strategy)) { 174 return new SleepingWaitStrategy(); 175 } else if ("Yield".equals(strategy)) { 176 return new YieldingWaitStrategy(); 177 } else if ("Block".equals(strategy)) { 178 return new BlockingWaitStrategy(); 179 } 180 LOGGER.debug("disruptor event handler uses BlockingWaitStrategy"); 181 return new BlockingWaitStrategy(); 182 } 183 184 private static ExceptionHandler getExceptionHandler() { 185 final String cls = System.getProperty("AsyncLogger.ExceptionHandler"); 186 if (cls == null) { 187 LOGGER.debug("No AsyncLogger.ExceptionHandler specified"); 188 return null; 189 } 190 try { 191 final ExceptionHandler result = Loader.newCheckedInstanceOf(cls, ExceptionHandler.class); 192 LOGGER.debug("AsyncLogger.ExceptionHandler={}", result); 193 return result; 194 } catch (final Exception ignored) { 195 LOGGER.debug("AsyncLogger.ExceptionHandler not set: error creating " + cls + ": ", ignored); 196 return null; 197 } 198 } 199 200 /** 201 * Constructs an {@code AsyncLogger} with the specified context, name and 202 * message factory. 203 * 204 * @param context context of this logger 205 * @param name name of this logger 206 * @param messageFactory message factory of this logger 207 */ 208 public AsyncLogger(final LoggerContext context, final String name, final MessageFactory messageFactory) { 209 super(context, name, messageFactory); 210 } 211 212 /** 213 * Tuple with the event translator and thread name for a thread. 214 */ 215 static class Info { 216 private final RingBufferLogEventTranslator translator; 217 private final String cachedThreadName; 218 private final boolean isAppenderThread; 219 public Info(final RingBufferLogEventTranslator translator, final String threadName, final boolean appenderThread) { 220 this.translator = translator; 221 this.cachedThreadName = threadName; 222 this.isAppenderThread = appenderThread; 223 } 224 } 225 226 @Override 227 public void logMessage(final String fqcn, final Level level, final Marker marker, final Message message, final Throwable thrown) { 228 Info info = threadlocalInfo.get(); 229 if (info == null) { 230 info = new Info(new RingBufferLogEventTranslator(), Thread.currentThread().getName(), false); 231 threadlocalInfo.set(info); 232 } 233 234 Disruptor<RingBufferLogEvent> temp = disruptor; 235 if (temp == null) { // LOG4J2-639 236 LOGGER.fatal("Ignoring log event after log4j was shut down"); 237 return; 238 } 239 240 // LOG4J2-471: prevent deadlock when RingBuffer is full and object 241 // being logged calls Logger.log() from its toString() method 242 if (info.isAppenderThread && temp.getRingBuffer().remainingCapacity() == 0) { 243 // bypass RingBuffer and invoke Appender directly 244 config.loggerConfig.log(getName(), fqcn, marker, level, message, thrown); 245 return; 246 } 247 final boolean includeLocation = config.loggerConfig.isIncludeLocation(); 248 info.translator.setValues(this, getName(), marker, fqcn, level, message, // 249 // don't construct ThrowableProxy until required 250 thrown, // 251 252 // config properties are taken care of in the EventHandler 253 // thread in the #actualAsyncLog method 254 255 // needs shallow copy to be fast (LOG4J2-154) 256 ThreadContext.getImmutableContext(), // 257 258 // needs shallow copy to be fast (LOG4J2-154) 259 ThreadContext.getImmutableStack(), // 260 261 // Thread.currentThread().getName(), // 262 // info.cachedThreadName, // 263 THREAD_NAME_STRATEGY.getThreadName(info), // LOG4J2-467 264 265 // location: very expensive operation. LOG4J2-153: 266 // Only include if "includeLocation=true" is specified, 267 // exclude if not specified or if "false" was specified. 268 includeLocation ? location(fqcn) : null, 269 270 // System.currentTimeMillis()); 271 // CoarseCachedClock: 20% faster than system clock, 16ms gaps 272 // CachedClock: 10% faster than system clock, smaller gaps 273 clock.currentTimeMillis()); 274 275 // LOG4J2-639: catch NPE if disruptor field was set to null after our check above 276 try { 277 // Note: do NOT use the temp variable above! 278 // That could result in adding a log event to the disruptor after it was shut down, 279 // which could cause the publishEvent method to hang and never return. 280 disruptor.publishEvent(info.translator); 281 } catch (NullPointerException npe) { 282 LOGGER.fatal("Ignoring log event after log4j was shut down."); 283 } 284 } 285 286 private static StackTraceElement location(final String fqcnOfLogger) { 287 return Log4jLogEvent.calcLocation(fqcnOfLogger); 288 } 289 290 /** 291 * This method is called by the EventHandler that processes the 292 * RingBufferLogEvent in a separate thread. 293 * 294 * @param event the event to log 295 */ 296 public void actualAsyncLog(final RingBufferLogEvent event) { 297 final Map<Property, Boolean> properties = config.loggerConfig.getProperties(); 298 event.mergePropertiesIntoContextMap(properties, config.config.getStrSubstitutor()); 299 config.logEvent(event); 300 } 301 302 public static void stop() { 303 final Disruptor<RingBufferLogEvent> temp = disruptor; 304 305 // Must guarantee that publishing to the RingBuffer has stopped 306 // before we call disruptor.shutdown() 307 disruptor = null; // client code fails with NPE if log after stop = OK 308 if (temp == null) { 309 return; // stop() has already been called 310 } 311 312 // Calling Disruptor.shutdown() will wait until all enqueued events are fully processed, 313 // but this waiting happens in a busy-spin. To avoid (postpone) wasting CPU, 314 // we sleep in short chunks, up to 10 seconds, waiting for the ringbuffer to drain. 315 for (int i = 0; hasBacklog(temp) && i < MAX_DRAIN_ATTEMPTS_BEFORE_SHUTDOWN; i++) { 316 try { 317 Thread.sleep(SLEEP_MILLIS_BETWEEN_DRAIN_ATTEMPTS); // give up the CPU for a while 318 } catch (final InterruptedException e) { // ignored 319 } 320 } 321 temp.shutdown(); // busy-spins until all events currently in the disruptor have been processed 322 executor.shutdown(); // finally, kill the processor thread 323 threadlocalInfo.remove(); // LOG4J2-323 324 } 325 326 /** 327 * Returns {@code true} if the specified disruptor still has unprocessed events. 328 */ 329 private static boolean hasBacklog(Disruptor<?> disruptor) { 330 final RingBuffer<?> ringBuffer = disruptor.getRingBuffer(); 331 return !ringBuffer.hasAvailableCapacity(ringBuffer.getBufferSize()); 332 } 333 334 /** 335 * Creates and returns a new {@code RingBufferAdmin} that instruments the 336 * ringbuffer of the {@code AsyncLogger}. 337 * 338 * @param contextName name of the global {@code AsyncLoggerContext} 339 */ 340 public static RingBufferAdmin createRingBufferAdmin(final String contextName) { 341 return RingBufferAdmin.forAsyncLogger(disruptor.getRingBuffer(), contextName); 342 } 343 }