我遇到一个奇怪的问题。我正在尝试使用生产者/消费者模型,请建议如果我在这里做错了什么。
当我使用固定线程4的ExecutorService时,我再也不会收到任何异常,并且当我使用ThreadPoolExecutor时程序会运行BUT,它给了我异常。无法找出错误所在!请指教!
ExecutorService的代码:
ArrayBlockingQueue<BillableList> list =new ArrayBlockingQueue<BillableList>(2);
ThreadFactory threadFactory = Executors.defaultThreadFactory();
ExecutorService threadPool = Executors.newFixedThreadPool(4, threadFactory);
threadPool.execute(new BillingConsu(network,"consumer->"+Thread.currentThread(), list));
threadPool.execute(new BillingConsu(network,"consumer->"+Thread.currentThread(), list));
threadPool.execute(new BillingConsu(network,"consumer->"+Thread.currentThread(), list));
Future producerStatus = threadPool.submit(new BillProdu(this.network,"Producer", list));
producerStatus.get();
threadPool.shutdown();
while (!threadPool.isTerminated()) {
threadPool.shutdown();
threadPool.awaitTermination(10, TimeUnit.SECONDS);
}
ThreadPoolExecutor的代码:
ArrayBlockingQueue<BillableList> list =new ArrayBlockingQueue<BillableList>(4);
BlockingQueue<Runnable> worksQueue = new ArrayBlockingQueue<Runnable>(100);
RejectedExecutionHandler executionHandler = new MyRejectedExecutionHandelerImpl();
ThreadFactory threadFactory = Executors.defaultThreadFactory();
ThreadPoolExecutor threadPool = new ThreadPoolExecutor(5,5, 10,
TimeUnit.SECONDS, worksQueue,threadFactory, executionHandler);
Future producerStatus = threadPool.submit(new BillProdu(this.network,"Producer", list));
producerStatus.get();
threadPool.execute(new BillingConsu(network,"consumer 1", list));
threadPool.execute(new BillingConsu(network,"consumer 2", list));
threadPool.execute(new BillingConsu(network,"consumer 3", list));
threadPool.execute(new BillingConsu(network,"consumer 4", list));
threadPool.shutdown();
while (!threadPool.isTerminated()) {
threadPool.shutdown();
threadPool.awaitTermination(10, TimeUnit.SECONDS);
}
当我运行ThreadPoolExecutor时发生异常:
Exception in thread "pool-1-thread-2" java.lang.ExceptionInInitializerError
at org.apache.axis.utils.Messages.<clinit>(Messages.java:36)
at org.apache.axis.configuration.EngineConfigurationFactoryFinder$1.run (EngineConfigurationFactoryFinder.java:141)
at java.security.AccessController.doPrivileged(Native Method)
at org.apache.axis.configuration.EngineConfigurationFactoryFinder.newFactory (EngineConfigurationFactoryFinder.java:113)
at org.apache.axis.configuration.EngineConfigurationFactoryFinder.newFactory (EngineConfigurationFactoryFinder.java:160)
at org.apache.axis.client.Service.getEngineConfiguration(Service.java:813)
at org.apache.axis.client.Service.getAxisClient(Service.java:104)
at org.apache.axis.client.Service.<init>(Service.java:113)
at org.tempuri.OnlineBillingLocator.<init>(OnlineBillingLocator.java:28)
at com.mixem.sdc.sms.StsSmsConnection.<init>(StsSmsConnection.java:40)
at BillingConsu.doStsBilling(BillingConsu.java:202)
at BillingConsu.run(BillingConsu.java:60)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NullPointerException
at java.io.FileOutputStream.<init>(FileOutputStream.java:172)
at java.io.FileOutputStream.<init>(FileOutputStream.java:102)
at org.apache.log4j.FileAppender.setFile(FileAppender.java:290)
at LogFileWriter.append(LogFileWriter.java:45)
at org.apache.log4j.AppenderSkeleton.doAppend(AppenderSkeleton.java:251)
at org.apache.log4j.helpers.AppenderAttachableImpl.appendLoopOnAppenders (AppenderAttachableImpl.java:66)
at org.apache.log4j.Category.callAppenders(Category.java:206)
at org.apache.log4j.Category.forcedLog(Category.java:391)
at org.apache.log4j.Category.log(Category.java:856)
at org.apache.commons.logging.impl.Log4JLogger.debug(Log4JLogger.java:177)
at org.apache.axis.i18n.ProjectResourceBundle.getBundle(ProjectResourceBundle.java:264)
at org.apache.axis.i18n.MessagesConstants.<clinit>(MessagesConstants.java:32)
Log4J属性文件
log4j.rootLogger = DEBUG, fileout
log4j.appender.fileout = LogFileWriter
log4j.appender.fileout.layout.ConversionPattern = %d{ABSOLUTE} %5p %c - %m%n
log4j.appender.fileout.layout = org.apache.log4j.PatternLayout
log4j.appender.fileout.File = /logs/billinglogs.log
LogFileWriter附加代码
@Override
public void append(LoggingEvent event) {
try {
setFile(appendLevelToFileName((String) MDC.get(ORIG_LOG_FILE_NAME),
event.getLevel().toString()), fileAppend, bufferedIO,bufferSize);
} catch (IOException ie) {
errorHandler.error("Error occured while setting file for the log level "+ event.getLevel(), ie,
ErrorCode.FILE_OPEN_FAILURE);
}
super.append(event);
}
MDC将代码放在LogFileWriter中
@Override
public void activateOptions() {
MDC.put(ORIG_LOG_FILE_NAME, fileName);
super.activateOptions();
}
最佳答案
如我所料,由于线程局部性,您将失败。几乎可以肯定,这里的行返回null
MDC.get(ORIG_LOG_FILE_NAME)
您何时/何地
MDC.put
?这里的问题是MDC使用线程本地映射。因此,当您运行Callable时,它将尝试登录一个单独的线程。该线程尚未在MDC中注册,并且get
将返回null。想象一下,您的应用程序看起来类似于
Main-Thread
MDC.put -> sets thread-local-map(Main-Thread, ORIG_LOG_FILE_NAME)
Executor-Thread-1
Executor-Thread-2
Executor-Thread-N
现在,当您处于Executor-Thread-1..N中时,它将执行
Executor-Thread-N
MDC.get(Executor-Thread-N, ORIG_LOG_FILE_NAME)
它将返回null
如果您在Executor Service线程之外运行,则可以正常运行
Main-Thread
MDC.get(Main-Thread, ORIG_LOG_FILE_NAME) // will be non-null
因此,您的下一个问题是:“为什么ExecutorService不会失败?”它可能已经或将会被报告,也可能不会被报告。我确实注意到您提交给ExecutorService的顺序不同于TPE。可能想尝试将它们匹配起来,看看是否获得相同的输出。
编辑:可能想尝试作为修复
ThreadFactory threadFactory = new ThreadFactory() {
public Thread newThread(final Runnable r) {
return Executors.defaultThreadFactory().newThread(new Runnable(){
public void run() {
MDC.put(ORIG_LOG_FILE_NAME, fileName);
r.run();
}
});
}
};
关于Java ExecutorService和ThreadPoolExecu,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/16790064/