Question

WorkManager是否限制同时运行的作业数量？

非常简单的示例：

单击按钮，创建10个一次性作业
全部入队
一次运行3个作业，而不是预期的全部10个

class MainActivity: AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_main)

        queue.setOnClickListener {
            val jobs = mutableListOf<OneTimeWorkRequest>()

            for( i in 1..10 ) {
                jobs += OneTimeWorkRequestBuilder<MyWorker>()
                    .setInputData(workDataOf("key" to i))
                    .build()
            }

            WorkManager.getInstance().enqueue(jobs)
        }
    }
}

class MyWorker: Worker() {
    override fun doWork(): Result {
        val jobId = inputData.getInt("key", -1)

        Log.d("worker", "starting job: $jobId")

        Completable.timer(10, SECONDS).blockingGet()

        Log.d("worker", "job finished: $jobId")

        return SUCCESS
    }
}

输出：

08-30 14:03:10.392  9825  9855 D worker  : starting job: 2
08-30 14:03:10.396  9825  9856 D worker  : starting job: 3
08-30 14:03:10.400  9825  9854 D worker  : starting job: 1
08-30 14:03:20.421  9825  9855 D worker  : job finished: 2
08-30 14:03:20.421  9825  9856 D worker  : job finished: 3
08-30 14:03:20.421  9825  9854 D worker  : job finished: 1
08-30 14:03:20.442  9825  9856 D worker  : starting job: 4
08-30 14:03:20.448  9825  9854 D worker  : starting job: 5
08-30 14:03:20.450  9825  9855 D worker  : starting job: 6
08-30 14:03:30.444  9825  9856 D worker  : job finished: 4
08-30 14:03:30.449  9825  9854 D worker  : job finished: 5
08-30 14:03:30.451  9825  9855 D worker  : job finished: 6
08-30 14:03:30.474  9825  9856 D worker  : starting job: 7
08-30 14:03:30.477  9825  9855 D worker  : starting job: 8
08-30 14:03:30.480  9825  9854 D worker  : starting job: 9
08-30 14:03:40.476  9825  9856 D worker  : job finished: 7
08-30 14:03:40.478  9825  9855 D worker  : job finished: 8
08-30 14:03:40.481  9825  9854 D worker  : job finished: 9
08-30 14:03:40.497  9825  9856 D worker  : starting job: 10
08-30 14:03:50.500  9825  9856 D worker  : job finished: 10

Answer 1

可以同时运行的作业数实际上由您配置的线程池确定。默认的Executor定义为here。

通常，当您使用Worker基类时，会将Worker的实例与该Executor上的线程相关联。如果您想更好地控制Worker与哪个线程相关联，则可以查看一下CoroutineWorker或ListenableWorker。

默认Executor中的线程数由设备上的内核数决定。如果要同时运行所有10个作业，则必须执行以下操作：

禁用默认的WorkManager初始化程序（通过为内容提供程序禁用清单合并）。
在WorkManager或您自己的Application.onCreate()上初始化ContentProvider。您需要在此处执行此操作，因为操作系统可以要求先前安排的Worker运行。有关更多信息，请查看this。

val configuration = Configuration.Builder()
    // Defines a thread pool with 10 threads. 
    // Ideally you would choose a number that is dynamic based on the number 
    // of cores on the device.
    .setExecutor(Executors.newFixedThreadPool(10))
    .build()

WorkManager.initialize(context, configuration)

在上面的示例中，我创建了一个具有10个线程的固定大小的线程池（该线程池又可以处理10个Workers）。现在，当您将Worker排入队列时，您将看到它们全部同时执行。

Android的WorkManager的同时作业数/最大值

1 个答案: