Android Priority Job Queue (Job Manager)：线程任务的容错重启机制（二）

缺乏、安全感 2023-10-17 08:58 231阅读 0赞

**Android Priority Job Queue (Job Manager)：线程任务的容错重启机制（二）**

附录文章4简单介绍了如何启动一个后台线程任务，Android Priority Job Queue (Job Manager)有一个重要的机制在附录文章4还没有体现：线程任务失败后重试、重启线程任务。这个机制在某些开发场景中非常常用，假设从网络中请求数据，但不幸的是网络出现故障，导致在线程体onRun内的代码失败，问题是失败该如何处理？这个时候，常规的做法是自己增加一堆状态字或者返回值加以控制，但是这样无疑使得开发者陷入繁琐的线程状态机的维护中来。  
Android Priority Job Queue (Job Manager)完整的解决上上述问题：容错重试回滚任务机制。具体体现在onRun和shouldReRunOnThrowable，如果一个线程任务在onRun里面抛出异常失败，那么将自动进入shouldReRunOnThrowable，然后在shouldReRunOnThrowable会决定是否重试RetryConstraint.RETRY，或者干脆放弃任务RetryConstraint.CANCEL，这里面的重试或者放弃逻辑策略由开发者决定，比如一般的，可以由重试次数决定线程是否还有必要执行，假设一个任务重试了3次仍然不成功，那么就放弃（返RetryConstraint.CANCEL）。一旦放弃后，代码将进入onCanel内，在这里面处理善后事宜，这个机制有些类似Java的try-catch机制。  
在附录文章4的基础上，仅仅修改MyJob.java代码演示上述机制：

package zhangphil.app;
    
    import android.os.SystemClock;
    import android.support.annotation.NonNull;
    import android.support.annotation.Nullable;
    import android.util.Log;
    
    import com.birbit.android.jobqueue.Job;
    import com.birbit.android.jobqueue.Params;
    import com.birbit.android.jobqueue.RetryConstraint;
    
    /**
     * Created by Phil on 2016/10/9.
     */
    public class MyJob extends Job {
    
        private String tag;
    
        public MyJob(String tag) {
            super(new Params(500).requireNetwork().persist().groupBy(tag));
            this.tag = tag;
            Log.d(tag, "初始化");
        }
    
        @Override
        public void onAdded() {
            Log.d(tag, "添加任务");
        }
    
        //在这里面放置耗时的后台线程化任务
        @Override
        public void onRun() throws Throwable {
            Log.d(tag, "开始运行...");
    
            SystemClock.sleep(2000);
    
            //此处抛出异常后，jobqueue将立即自动进入shouldReRunOnThrowable
            throw new Exception();
    
            //Log.d(tag, "完成");
        }
    
        @Override
        protected RetryConstraint shouldReRunOnThrowable(@NonNull Throwable throwable, int runCount, int maxRunCount) {
            // An error occurred in onRun.
            // Return value determines whether this job should retry or cancel. You can further
            // specify a backoff strategy or change the job's priority. You can also apply the
            // delay to the whole group to preserve jobs' running order.
    
            Log.d(tag, "runCount: " + runCount + " maxRunCount: " + maxRunCount);
    
            //如果重试了3次仍未成功，那么就放弃执行任务
            if (runCount == 3)
                return RetryConstraint.CANCEL;
    
            //这样的返回将导致onRun方法的再次执行，重试,重试将导致代码再次进入onRun。同时，runCount自加1
            return RetryConstraint.RETRY;
        }
    
        //如果重试超过限定次数，将onCancel.
        //如果用户主动放弃删掉这个任务，也一样进入onCancel
        @Override
        protected void onCancel(int cancelReason, @Nullable Throwable throwable) {
            Log.d(tag, "cancelReason：" + cancelReason);
        }
    }

代码运行后Logcat完整输出：

10-10 15:51:39.488 16856-16856/zhangphil.app D/任务1: 初始化
    10-10 15:51:39.488 16856-16856/zhangphil.app D/zhangphil job: [queue_ADD_JOB_2] post message com.birbit.android.jobqueue.messaging.message.AddJobMessage@b1a3ff0
    10-10 15:51:39.488 16856-16856/zhangphil.app D/Activity: performCreate Call Injection manager
    10-10 15:51:39.488 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085899495109636
    10-10 15:51:39.488 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085899495109636
    10-10 15:51:39.488 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:39.488 16856-17353/zhangphil.app D/zhangphil job: [queue_ADD_JOB_2] remove message com.birbit.android.jobqueue.messaging.message.AddJobMessage@b1a3ff0
    10-10 15:51:39.488 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] consuming message of type ADD_JOB
    10-10 15:51:39.488 16856-16856/zhangphil.app I/InjectionManager: dispatchOnViewCreated > Target : zhangphil.app.MainActivity isFragment :false
    10-10 15:51:39.528 16856-17353/zhangphil.app D/zhangphil job: added job class: MyJob priority: 500 delay: 0 group : 任务1 persistent: true
    10-10 15:51:39.528 16856-17353/zhangphil.app D/任务1: 添加任务
    10-10 15:51:39.528 16856-17353/zhangphil.app D/zhangphil job: considering adding a new consumer. Should poke all waiting? false isRunning? true waiting workers? 0
    10-10 15:51:39.528 16856-17353/zhangphil.app D/zhangphil job: check above load factor: totalCons:0 minCons:1 maxConsCount: 3, loadFactor 3 remainingJobs: 1 running holders: 0. isAbove:true
    10-10 15:51:39.528 16856-17353/zhangphil.app D/zhangphil job: nothing has been poked. are we above load factor? true
    10-10 15:51:39.528 16856-17353/zhangphil.app D/zhangphil job: adding another consumer
    10-10 15:51:39.538 16856-16856/zhangphil.app D/SecWifiDisplayUtil: Metadata value : SecSettings2
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085899551798802
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085899551798802
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:39.548 16856-16856/zhangphil.app D/ViewRootImpl: #1 mView = com.android.internal.policy.PhoneWindow$DecorView{8602777 I.E...... R.....ID 0,0-0,0}
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [queue_ADD_JOB_2] remove message null
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: joq idle. running:? true
    10-10 15:51:39.548 16856-17358/zhangphil.app D/zhangphil job: flushing messages at time 1476085899553556250
    10-10 15:51:39.548 16856-17358/zhangphil.app D/zhangphil job: [consumer_3] remove message null
    10-10 15:51:39.548 16856-17358/zhangphil.app D/zhangphil job: consumer manager on idle
    10-10 15:51:39.548 16856-17358/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] post message com.birbit.android.jobqueue.messaging.message.JobConsumerIdleMessage@a013fe4
    10-10 15:51:39.548 16856-17358/zhangphil.app D/zhangphil job: [consumer_3] will wait on the lock forever
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: Job queue idle. next job at: -9223372036854775808
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: add delayed message com.birbit.android.jobqueue.messaging.message.ConstraintChangeMessage@257dc4d at time -9223372036854775808
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] did on idle post a message? true
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085899555766615
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085899555766615
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [queue_CONSTRAINT_CHANGE_5] post message com.birbit.android.jobqueue.messaging.message.ConstraintChangeMessage@257dc4d
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [queue_CONSTRAINT_CHANGE_5] remove message com.birbit.android.jobqueue.messaging.message.ConstraintChangeMessage@257dc4d
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] consuming message of type CONSTRAINT_CHANGE
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: considering adding a new consumer. Should poke all waiting? true isRunning? true waiting workers? 0
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: check above load factor: totalCons:1 minCons:1 maxConsCount: 3, loadFactor 3 remainingJobs: 1 running holders: 0. isAbove:false
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: nothing has been poked. are we above load factor? false
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085899559063386
    10-10 15:51:39.548 16856-17359/zhangphil.app D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085899559063386
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [queue_CONSTRAINT_CHANGE_5] remove message null
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [queue_ADD_JOB_2] remove message null
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] remove message com.birbit.android.jobqueue.messaging.message.JobConsumerIdleMessage@a013fe4
    10-10 15:51:39.548 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] consuming message of type JOB_CONSUMER_IDLE
    10-10 15:51:39.558 16856-16856/zhangphil.app W/ActivityThread: AppLock checkAppLockState isAppLocked = false pkgName = zhangphil.app showWhenLocked = false
    10-10 15:51:39.568 16856-17353/zhangphil.app D/zhangphil job: [consumer_3] post message com.birbit.android.jobqueue.messaging.message.RunJobMessage@725c413
    10-10 15:51:39.568 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085899571643802
    10-10 15:51:39.568 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085899571643802
    10-10 15:51:39.568 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:39.568 16856-17353/zhangphil.app D/zhangphil job: [queue_CONSTRAINT_CHANGE_5] remove message null
    10-10 15:51:39.568 16856-17353/zhangphil.app D/zhangphil job: [queue_ADD_JOB_2] remove message null
    10-10 15:51:39.568 16856-17353/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] remove message null
    10-10 15:51:39.568 16856-17353/zhangphil.app D/zhangphil job: joq idle. running:? true
    10-10 15:51:39.568 16856-17358/zhangphil.app D/zhangphil job: flushing messages at time 1476085899571733438
    10-10 15:51:39.568 16856-17358/zhangphil.app D/zhangphil job: [consumer_3] remove message com.birbit.android.jobqueue.messaging.message.RunJobMessage@725c413
    10-10 15:51:39.568 16856-17358/zhangphil.app D/zhangphil job: running job JobHolder
    10-10 15:51:39.568 16856-17358/zhangphil.app D/zhangphil job: running job MyJob
    10-10 15:51:39.568 16856-17358/zhangphil.app D/任务1: 开始运行...
    10-10 15:51:39.568 16856-17353/zhangphil.app D/zhangphil job: Job queue idle. next job at: null
    10-10 15:51:39.568 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] did on idle post a message? false
    10-10 15:51:39.588 16856-17359/zhangphil.app I/Adreno: QUALCOMM build                   : 0039a8c, I5bc0f577f9
                                                           Build Date                       : 08/03/16
                                                           OpenGL ES Shader Compiler Version: XE031.08.00.02
                                                           Local Branch                     : 
                                                           Remote Branch                    : refs/tags/AU_LINUX_ANDROID_LA.HB.1.1.1.C1.06.00.00.165.223
                                                           Remote Branch                    : NONE
                                                           Reconstruct Branch               : NOTHING
    10-10 15:51:39.588 16856-17359/zhangphil.app D/libEGL: eglInitialize EGLDisplay = 0x7f93bfa188
    10-10 15:51:39.588 16856-17359/zhangphil.app I/OpenGLRenderer: Initialized EGL, version 1.4
    10-10 15:51:39.618 16856-16856/zhangphil.app D/ViewRootImpl: MSG_RESIZED_REPORT: ci=Rect(0, 96 - 0, 0) vi=Rect(0, 96 - 0, 0) or=1
    10-10 15:51:39.628 16856-16856/zhangphil.app W/DisplayListCanvas: DisplayListCanvas is started on unbinded RenderNode (without mOwningView)
    10-10 15:51:39.668 16856-16856/zhangphil.app I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@87b6b1c time:249284264
    10-10 15:51:41.568 16856-17358/zhangphil.app E/zhangphil job: error while executing job zhangphil.app.MyJob@9eb605a
                                                                  java.lang.Exception
                                                                      at zhangphil.app.MyJob.onRun(MyJob.java:38)
                                                                      at com.birbit.android.jobqueue.Job.safeRun(Job.java:229)
                                                                      at com.birbit.android.jobqueue.JobHolder.safeRun(JobHolder.java:132)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer.handleRunJob(ConsumerManager.java:398)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer.access$000(ConsumerManager.java:317)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer$2.handleMessage(ConsumerManager.java:345)
                                                                      at com.birbit.android.jobqueue.messaging.SafeMessageQueue.consume(SafeMessageQueue.java:36)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer.run(ConsumerManager.java:380)
                                                                      at java.lang.Thread.run(Thread.java:818)
    10-10 15:51:41.568 16856-17358/zhangphil.app D/任务1: runCount: 1 maxRunCount: 20
    10-10 15:51:41.568 16856-17358/zhangphil.app D/zhangphil job: safeRunResult for zhangphil.app.MyJob@9eb605a : false. re run:true. cancelled: false
    10-10 15:51:41.578 16856-17358/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] post message com.birbit.android.jobqueue.messaging.message.RunJobResultMessage@2fa28b
    10-10 15:51:41.578 16856-17358/zhangphil.app D/zhangphil job: flushing messages at time 1476085901581361354
    10-10 15:51:41.578 16856-17358/zhangphil.app D/zhangphil job: [consumer_3] remove message null
    10-10 15:51:41.578 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085901581436927
    10-10 15:51:41.578 16856-17358/zhangphil.app D/zhangphil job: consumer manager on idle
    10-10 15:51:41.578 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085901581436927
    10-10 15:51:41.578 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:41.578 16856-17353/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] remove message com.birbit.android.jobqueue.messaging.message.RunJobResultMessage@2fa28b
    10-10 15:51:41.578 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] consuming message of type RUN_JOB_RESULT
    10-10 15:51:41.578 16856-17358/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] post message com.birbit.android.jobqueue.messaging.message.JobConsumerIdleMessage@a013fe4
    10-10 15:51:41.578 16856-17358/zhangphil.app D/zhangphil job: [consumer_3] will wait on the lock forever
    10-10 15:51:41.598 16856-17353/zhangphil.app D/zhangphil job: reinsert job result true
    10-10 15:51:41.598 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085901603381718
    10-10 15:51:41.598 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085901603381718
    10-10 15:51:41.598 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:41.598 16856-17353/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] remove message null
    10-10 15:51:41.598 16856-17353/zhangphil.app D/zhangphil job: [queue_CONSTRAINT_CHANGE_5] remove message null
    10-10 15:51:41.598 16856-17353/zhangphil.app D/zhangphil job: [queue_ADD_JOB_2] remove message null
    10-10 15:51:41.598 16856-17353/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] remove message com.birbit.android.jobqueue.messaging.message.JobConsumerIdleMessage@a013fe4
    10-10 15:51:41.598 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] consuming message of type JOB_CONSUMER_IDLE
    10-10 15:51:41.608 16856-17353/zhangphil.app D/zhangphil job: [consumer_3] post message com.birbit.android.jobqueue.messaging.message.RunJobMessage@725c413
    10-10 15:51:41.608 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085901615635572
    10-10 15:51:41.608 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085901615635572
    10-10 15:51:41.608 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:41.608 16856-17353/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] remove message null
    10-10 15:51:41.608 16856-17353/zhangphil.app D/zhangphil job: [queue_CONSTRAINT_CHANGE_5] remove message null
    10-10 15:51:41.608 16856-17353/zhangphil.app D/zhangphil job: [queue_ADD_JOB_2] remove message null
    10-10 15:51:41.608 16856-17358/zhangphil.app D/zhangphil job: flushing messages at time 1476085901615705104
    10-10 15:51:41.608 16856-17353/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] remove message null
    10-10 15:51:41.608 16856-17353/zhangphil.app D/zhangphil job: joq idle. running:? true
    10-10 15:51:41.608 16856-17358/zhangphil.app D/zhangphil job: [consumer_3] remove message com.birbit.android.jobqueue.messaging.message.RunJobMessage@725c413
    10-10 15:51:41.608 16856-17358/zhangphil.app D/zhangphil job: running job JobHolder
    10-10 15:51:41.608 16856-17358/zhangphil.app D/zhangphil job: running job MyJob
    10-10 15:51:41.608 16856-17358/zhangphil.app D/任务1: 开始运行...
    10-10 15:51:41.608 16856-17353/zhangphil.app D/zhangphil job: Job queue idle. next job at: null
    10-10 15:51:41.618 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] did on idle post a message? false
    10-10 15:51:43.608 16856-17358/zhangphil.app E/zhangphil job: error while executing job zhangphil.app.MyJob@1ef2826
                                                                  java.lang.Exception
                                                                      at zhangphil.app.MyJob.onRun(MyJob.java:38)
                                                                      at com.birbit.android.jobqueue.Job.safeRun(Job.java:229)
                                                                      at com.birbit.android.jobqueue.JobHolder.safeRun(JobHolder.java:132)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer.handleRunJob(ConsumerManager.java:398)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer.access$000(ConsumerManager.java:317)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer$2.handleMessage(ConsumerManager.java:345)
                                                                      at com.birbit.android.jobqueue.messaging.SafeMessageQueue.consume(SafeMessageQueue.java:36)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer.run(ConsumerManager.java:380)
                                                                      at java.lang.Thread.run(Thread.java:818)
    10-10 15:51:43.608 16856-17358/zhangphil.app D/任务1: runCount: 2 maxRunCount: 20
    10-10 15:51:43.608 16856-17358/zhangphil.app D/zhangphil job: safeRunResult for zhangphil.app.MyJob@1ef2826 : false. re run:true. cancelled: false
    10-10 15:51:43.608 16856-17358/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] post message com.birbit.android.jobqueue.messaging.message.RunJobResultMessage@2fa28b
    10-10 15:51:43.608 16856-17358/zhangphil.app D/zhangphil job: flushing messages at time 1476085903619928280
    10-10 15:51:43.608 16856-17358/zhangphil.app D/zhangphil job: [consumer_3] remove message null
    10-10 15:51:43.608 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085903620000572
    10-10 15:51:43.608 16856-17358/zhangphil.app D/zhangphil job: consumer manager on idle
    10-10 15:51:43.608 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085903620000572
    10-10 15:51:43.608 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:43.608 16856-17353/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] remove message com.birbit.android.jobqueue.messaging.message.RunJobResultMessage@2fa28b
    10-10 15:51:43.618 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] consuming message of type RUN_JOB_RESULT
    10-10 15:51:43.618 16856-17358/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] post message com.birbit.android.jobqueue.messaging.message.JobConsumerIdleMessage@a013fe4
    10-10 15:51:43.618 16856-17358/zhangphil.app D/zhangphil job: [consumer_3] will wait on the lock forever
    10-10 15:51:43.628 16856-17353/zhangphil.app D/zhangphil job: reinsert job result true
    10-10 15:51:43.628 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085903636682603
    10-10 15:51:43.628 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085903636682603
    10-10 15:51:43.628 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:43.628 16856-17353/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] remove message null
    10-10 15:51:43.628 16856-17353/zhangphil.app D/zhangphil job: [queue_CONSTRAINT_CHANGE_5] remove message null
    10-10 15:51:43.628 16856-17353/zhangphil.app D/zhangphil job: [queue_ADD_JOB_2] remove message null
    10-10 15:51:43.628 16856-17353/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] remove message com.birbit.android.jobqueue.messaging.message.JobConsumerIdleMessage@a013fe4
    10-10 15:51:43.628 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] consuming message of type JOB_CONSUMER_IDLE
    10-10 15:51:43.638 16856-17353/zhangphil.app D/zhangphil job: [consumer_3] post message com.birbit.android.jobqueue.messaging.message.RunJobMessage@725c413
    10-10 15:51:43.638 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085903643573436
    10-10 15:51:43.638 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085903643573436
    10-10 15:51:43.638 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:43.638 16856-17353/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] remove message null
    10-10 15:51:43.638 16856-17353/zhangphil.app D/zhangphil job: [queue_CONSTRAINT_CHANGE_5] remove message null
    10-10 15:51:43.638 16856-17358/zhangphil.app D/zhangphil job: flushing messages at time 1476085903643628228
    10-10 15:51:43.638 16856-17353/zhangphil.app D/zhangphil job: [queue_ADD_JOB_2] remove message null
    10-10 15:51:43.638 16856-17353/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] remove message null
    10-10 15:51:43.638 16856-17353/zhangphil.app D/zhangphil job: joq idle. running:? true
    10-10 15:51:43.638 16856-17358/zhangphil.app D/zhangphil job: [consumer_3] remove message com.birbit.android.jobqueue.messaging.message.RunJobMessage@725c413
    10-10 15:51:43.638 16856-17358/zhangphil.app D/zhangphil job: running job JobHolder
    10-10 15:51:43.638 16856-17358/zhangphil.app D/zhangphil job: running job MyJob
    10-10 15:51:43.638 16856-17358/zhangphil.app D/任务1: 开始运行...
    10-10 15:51:43.638 16856-17353/zhangphil.app D/zhangphil job: Job queue idle. next job at: null
    10-10 15:51:43.638 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] did on idle post a message? false
    10-10 15:51:45.638 16856-17358/zhangphil.app E/zhangphil job: error while executing job zhangphil.app.MyJob@12572bd
                                                                  java.lang.Exception
                                                                      at zhangphil.app.MyJob.onRun(MyJob.java:38)
                                                                      at com.birbit.android.jobqueue.Job.safeRun(Job.java:229)
                                                                      at com.birbit.android.jobqueue.JobHolder.safeRun(JobHolder.java:132)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer.handleRunJob(ConsumerManager.java:398)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer.access$000(ConsumerManager.java:317)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer$2.handleMessage(ConsumerManager.java:345)
                                                                      at com.birbit.android.jobqueue.messaging.SafeMessageQueue.consume(SafeMessageQueue.java:36)
                                                                      at com.birbit.android.jobqueue.ConsumerManager$Consumer.run(ConsumerManager.java:380)
                                                                      at java.lang.Thread.run(Thread.java:818)
    10-10 15:51:45.638 16856-17358/zhangphil.app D/任务1: runCount: 3 maxRunCount: 20
    10-10 15:51:45.638 16856-17358/zhangphil.app D/zhangphil job: safeRunResult for zhangphil.app.MyJob@12572bd : false. re run:false. cancelled: false
    10-10 15:51:45.638 16856-17358/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] post message com.birbit.android.jobqueue.messaging.message.RunJobResultMessage@2fa28b
    10-10 15:51:45.638 16856-17358/zhangphil.app D/zhangphil job: flushing messages at time 1476085905647085571
    10-10 15:51:45.638 16856-17358/zhangphil.app D/zhangphil job: [consumer_3] remove message null
    10-10 15:51:45.638 16856-17358/zhangphil.app D/zhangphil job: consumer manager on idle
    10-10 15:51:45.638 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085905647246300
    10-10 15:51:45.638 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085905647246300
    10-10 15:51:45.638 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:45.638 16856-17353/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] remove message com.birbit.android.jobqueue.messaging.message.RunJobResultMessage@2fa28b
    10-10 15:51:45.638 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] consuming message of type RUN_JOB_RESULT
    10-10 15:51:45.638 16856-17353/zhangphil.app D/任务1: cancelReason：5
    10-10 15:51:45.638 16856-17358/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] post message com.birbit.android.jobqueue.messaging.message.JobConsumerIdleMessage@a013fe4
    10-10 15:51:45.638 16856-17358/zhangphil.app D/zhangphil job: [consumer_3] will wait on the lock forever
    10-10 15:51:45.658 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085905666501300
    10-10 15:51:45.658 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085905666501300
    10-10 15:51:45.658 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:45.658 16856-17353/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] remove message null
    10-10 15:51:45.658 16856-17353/zhangphil.app D/zhangphil job: [queue_CONSTRAINT_CHANGE_5] remove message null
    10-10 15:51:45.658 16856-17353/zhangphil.app D/zhangphil job: [queue_ADD_JOB_2] remove message null
    10-10 15:51:45.658 16856-17353/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] remove message com.birbit.android.jobqueue.messaging.message.JobConsumerIdleMessage@a013fe4
    10-10 15:51:45.658 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] consuming message of type JOB_CONSUMER_IDLE
    10-10 15:51:45.668 16856-17353/zhangphil.app D/zhangphil job: keep alive: 1476086025647041248
    10-10 15:51:45.668 16856-17353/zhangphil.app D/zhangphil job: Consumer idle, will kill? false . isRunning: true
    10-10 15:51:45.668 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] looking for next message at time 1476085905680193019
    10-10 15:51:45.668 16856-17353/zhangphil.app D/zhangphil job: flushing messages at time 1476085905680193019
    10-10 15:51:45.668 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] next delayed job null
    10-10 15:51:45.668 16856-17353/zhangphil.app D/zhangphil job: [queue_RUN_JOB_RESULT_6] remove message null
    10-10 15:51:45.678 16856-17353/zhangphil.app D/zhangphil job: [queue_CONSTRAINT_CHANGE_5] remove message null
    10-10 15:51:45.678 16856-17353/zhangphil.app D/zhangphil job: [queue_ADD_JOB_2] remove message null
    10-10 15:51:45.678 16856-17353/zhangphil.app D/zhangphil job: [queue_JOB_CONSUMER_IDLE_4] remove message null
    10-10 15:51:45.678 16856-17353/zhangphil.app D/zhangphil job: joq idle. running:? true
    10-10 15:51:45.678 16856-17353/zhangphil.app D/zhangphil job: Job queue idle. next job at: null
    10-10 15:51:45.678 16856-17353/zhangphil.app D/zhangphil job: [priority_mq] did on idle post a message? false

上述完整Logcat输出显示了代码在onRun里面抛出异常然后容错回滚机制发挥作用重启了任务，过滤“任务”后精简的关键Logcat输出：

10-10 15:51:39.488 16856-16856/zhangphil.app D/任务1: 初始化
    10-10 15:51:39.528 16856-17353/zhangphil.app D/zhangphil job: added job class: MyJob priority: 500 delay: 0 group : 任务1 persistent: true
    10-10 15:51:39.528 16856-17353/zhangphil.app D/任务1: 添加任务
    10-10 15:51:39.568 16856-17358/zhangphil.app D/任务1: 开始运行...
    10-10 15:51:41.568 16856-17358/zhangphil.app D/任务1: runCount: 1 maxRunCount: 20
    10-10 15:51:41.608 16856-17358/zhangphil.app D/任务1: 开始运行...
    10-10 15:51:43.608 16856-17358/zhangphil.app D/任务1: runCount: 2 maxRunCount: 20
    10-10 15:51:43.638 16856-17358/zhangphil.app D/任务1: 开始运行...
    10-10 15:51:45.638 16856-17358/zhangphil.app D/任务1: runCount: 3 maxRunCount: 20
    10-10 15:51:45.638 16856-17353/zhangphil.app D/任务1: cancelReason：5

附录：  
【1】《Java线程池：ExecutorService，Executors》链接地址：[http://blog.csdn.net/zhangphil/article/details/43898637][http_blog.csdn.net_zhangphil_article_details_43898637]  
【2】《Java线程池及Future、Callable获得线程返回结果【Java线程池系列2】》链接地址：[http://blog.csdn.net/zhangphil/article/details/49701219][http_blog.csdn.net_zhangphil_article_details_49701219]  
【3】《Java线程池之FutureTask【Java线程池系列3】》链接地址：[http://blog.csdn.net/zhangphil/article/details/49702751][http_blog.csdn.net_zhangphil_article_details_49702751]  
【4】《Android Priority Job Queue (Job Manager)（一）》链接地址：[http://blog.csdn.net/zhangphil/article/details/52777196][http_blog.csdn.net_zhangphil_article_details_52777196]

[http_blog.csdn.net_zhangphil_article_details_43898637]: http://blog.csdn.net/zhangphil/article/details/43898637
[http_blog.csdn.net_zhangphil_article_details_49701219]: http://blog.csdn.net/zhangphil/article/details/49701219
[http_blog.csdn.net_zhangphil_article_details_49702751]: http://blog.csdn.net/zhangphil/article/details/49702751
[http_blog.csdn.net_zhangphil_article_details_52777196]: http://blog.csdn.net/zhangphil/article/details/52777196