Java tutorial
/* Licensed 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.flowable.engine.impl.asyncexecutor; import java.util.concurrent.ArrayBlockingQueue; import java.util.concurrent.BlockingQueue; import java.util.concurrent.ExecutorService; import java.util.concurrent.RejectedExecutionException; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; import org.apache.commons.lang3.concurrent.BasicThreadFactory; import org.flowable.engine.impl.context.Context; import org.flowable.engine.impl.interceptor.Command; import org.flowable.engine.impl.interceptor.CommandContext; import org.flowable.engine.runtime.Job; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * @author Joram Barrez * @author Tijs Rademakers */ public class DefaultAsyncJobExecutor extends AbstractAsyncExecutor { private static Logger log = LoggerFactory.getLogger(DefaultAsyncJobExecutor.class); protected Thread timerJobAcquisitionThread; protected Thread asyncJobAcquisitionThread; protected Thread resetExpiredJobThread; /** * The minimal number of threads that are kept alive in the threadpool for job execution */ protected int corePoolSize = 2; /** * The maximum number of threads that are kept alive in the threadpool for job execution */ protected int maxPoolSize = 10; /** * The time (in milliseconds) a thread used for job execution must be kept alive before it is destroyed. Default setting is 0. Having a non-default setting of 0 takes resources, but in the case of * many job executions it avoids creating new threads all the time. */ protected long keepAliveTime = 5000L; /** The size of the queue on which jobs to be executed are placed */ protected int queueSize = 100; /** Whether to unlock jobs that are owned by this executor (have the same lockOwner) at startup */ protected boolean unlockOwnedJobs = false; /** The queue used for job execution work */ protected BlockingQueue<Runnable> threadPoolQueue; /** The executor service used for job execution */ protected ExecutorService executorService; /** * The time (in seconds) that is waited to gracefully shut down the threadpool used for job execution */ protected long secondsToWaitOnShutdown = 60L; protected boolean executeAsyncJob(final Job job, Runnable runnable) { try { executorService.execute(runnable); return true; } catch (RejectedExecutionException e) { // When a RejectedExecutionException is caught, this means that the queue for holding the jobs // that are to be executed is full and can't store more. // The job is now 'unlocked', meaning that the lock owner/time is set to null, // so other executors can pick the job up (or this async executor, the next time the // acquire query is executed. // This can happen while already in a command context (for example in a transaction listener // after the async executor has been hinted that a new async job is created) // or not (when executed in the acquire thread runnable) CommandContext commandContext = Context.getCommandContext(); if (commandContext != null) { commandContext.getJobManager().unacquire(job); } else { processEngineConfiguration.getCommandExecutor().execute(new Command<Void>() { public Void execute(CommandContext commandContext) { commandContext.getJobManager().unacquire(job); return null; } }); } // Job queue full, returning true so (if wanted) the acquiring can be throttled return false; } } @Override protected void startAdditionalComponents() { if (!isMessageQueueMode) { initAsyncJobExecutionThreadPool(); startJobAcquisitionThread(); } startTimerAcquisitionThread(); startResetExpiredJobsThread(); } @Override protected void shutdownAdditionalComponents() { stopResetExpiredJobsThread(); stopTimerAcquisitionThread(); stopJobAcquisitionThread(); stopExecutingAsyncJobs(); } protected void initAsyncJobExecutionThreadPool() { if (threadPoolQueue == null) { log.info("Creating thread pool queue of size {}", queueSize); threadPoolQueue = new ArrayBlockingQueue<Runnable>(queueSize); } if (executorService == null) { log.info("Creating executor service with corePoolSize {}, maxPoolSize {} and keepAliveTime {}", corePoolSize, maxPoolSize, keepAliveTime); BasicThreadFactory threadFactory = new BasicThreadFactory.Builder() .namingPattern("flowable-async-job-executor-thread-%d").build(); executorService = new ThreadPoolExecutor(corePoolSize, maxPoolSize, keepAliveTime, TimeUnit.MILLISECONDS, threadPoolQueue, threadFactory); } if (unlockOwnedJobs) { unlockOwnedJobs(); } } protected void stopExecutingAsyncJobs() { if (executorService != null) { // Ask the thread pool to finish and exit executorService.shutdown(); // Waits for 1 minute to finish all currently executing jobs try { if (!executorService.awaitTermination(secondsToWaitOnShutdown, TimeUnit.SECONDS)) { log.warn( "Timeout during shutdown of async job executor. The current running jobs could not end within {} seconds after shutdown operation.", secondsToWaitOnShutdown); } } catch (InterruptedException e) { log.warn("Interrupted while shutting down the async job executor. ", e); } executorService = null; } } /** Starts the acquisition thread */ protected void startJobAcquisitionThread() { if (asyncJobAcquisitionThread == null) { asyncJobAcquisitionThread = new Thread(asyncJobsDueRunnable); } asyncJobAcquisitionThread.start(); } protected void startTimerAcquisitionThread() { if (timerJobAcquisitionThread == null) { timerJobAcquisitionThread = new Thread(timerJobRunnable); } timerJobAcquisitionThread.start(); } /** Stops the acquisition thread */ protected void stopJobAcquisitionThread() { if (asyncJobAcquisitionThread != null) { try { asyncJobAcquisitionThread.join(); } catch (InterruptedException e) { log.warn("Interrupted while waiting for the async job acquisition thread to terminate", e); } asyncJobAcquisitionThread = null; } } protected void stopTimerAcquisitionThread() { if (timerJobAcquisitionThread != null) { try { timerJobAcquisitionThread.join(); } catch (InterruptedException e) { log.warn("Interrupted while waiting for the timer job acquisition thread to terminate", e); } timerJobAcquisitionThread = null; } } /** Starts the reset expired jobs thread */ protected void startResetExpiredJobsThread() { if (resetExpiredJobThread == null) { resetExpiredJobThread = new Thread(resetExpiredJobsRunnable); } resetExpiredJobThread.start(); } /** Stops the reset expired jobs thread */ protected void stopResetExpiredJobsThread() { if (resetExpiredJobThread != null) { try { resetExpiredJobThread.join(); } catch (InterruptedException e) { log.warn("Interrupted while waiting for the reset expired jobs thread to terminate", e); } resetExpiredJobThread = null; } } public Thread getTimerJobAcquisitionThread() { return timerJobAcquisitionThread; } public void setTimerJobAcquisitionThread(Thread timerJobAcquisitionThread) { this.timerJobAcquisitionThread = timerJobAcquisitionThread; } public Thread getAsyncJobAcquisitionThread() { return asyncJobAcquisitionThread; } public void setAsyncJobAcquisitionThread(Thread asyncJobAcquisitionThread) { this.asyncJobAcquisitionThread = asyncJobAcquisitionThread; } public Thread getResetExpiredJobThread() { return resetExpiredJobThread; } public void setResetExpiredJobThread(Thread resetExpiredJobThread) { this.resetExpiredJobThread = resetExpiredJobThread; } public int getQueueSize() { return queueSize; } @Override public int getRemainingCapacity() { return threadPoolQueue.remainingCapacity(); } public void setQueueSize(int queueSize) { this.queueSize = queueSize; } public int getCorePoolSize() { return corePoolSize; } public void setCorePoolSize(int corePoolSize) { this.corePoolSize = corePoolSize; } public int getMaxPoolSize() { return maxPoolSize; } public void setMaxPoolSize(int maxPoolSize) { this.maxPoolSize = maxPoolSize; } public long getKeepAliveTime() { return keepAliveTime; } public void setKeepAliveTime(long keepAliveTime) { this.keepAliveTime = keepAliveTime; } public long getSecondsToWaitOnShutdown() { return secondsToWaitOnShutdown; } public void setSecondsToWaitOnShutdown(long secondsToWaitOnShutdown) { this.secondsToWaitOnShutdown = secondsToWaitOnShutdown; } public boolean isUnlockOwnedJobs() { return unlockOwnedJobs; } public void setUnlockOwnedJobs(boolean unlockOwnedJobs) { this.unlockOwnedJobs = unlockOwnedJobs; } public BlockingQueue<Runnable> getThreadPoolQueue() { return threadPoolQueue; } public void setThreadPoolQueue(BlockingQueue<Runnable> threadPoolQueue) { this.threadPoolQueue = threadPoolQueue; } public ExecutorService getExecutorService() { return executorService; } public void setExecutorService(ExecutorService executorService) { this.executorService = executorService; } }