HarmonyOS taskpool取消问题?

Question

taskpool在onReceiveData的fun里调用cancel报错如下：

taskpool:: query non-existent task 
04-11 15:48:33.672 20008-20008 C03f00/ArkCompiler com.example.nbody E BusinessError: The task does not exist when it is canceled

Answer 1

这是因为taskpool执行完毕了，任务被释放。
可以通过如下DEMO验证：

import { hilog } from '@kit.PerformanceAnalysisKit'; 
import { taskpool } from '@kit.ArkTS'; 
@Concurrent 
function TestCancelTaskPool(): Boolean { 
  hilog.info(0x0000, 'testTag', '%{public}s', 'enter TestCancelTaskPool'); 
  let nowNum = Date.now(); 
  while (true) { 
    let nowNum2 = Date.now(); 
    if (nowNum2 - nowNum > 3000) { 
      hilog.info(0x0000, 'testTag', '%{public}s', 'TestCancelTaskPool while break'); 
      break; 
    } 
  } 
  hilog.info(0x0000, 'testTag', '%{public}s', 'end TestCancelTaskPool'); 
  return true; 
} 
@Entry 
@Component 
struct Index { 
  task?: taskpool.Task 
  build() { 
    Column() { 
      Row() { 
        Text('启动') 
          .fontSize(50) 
          .fontWeight(FontWeight.Bold) 
          .onClick(() => { 
            this.task = new taskpool.Task(TestCancelTaskPool); 
            taskpool.execute(this.task).then((value: Object) => { 
              hilog.info(0x0000, 'testTag', '%{public}s', 'taskpool run finish'); 
            }) 
          }) 
      } 
      Divider() 
      Row() { 
        Text('取消') 
          .fontSize(50) 
          .fontWeight(FontWeight.Bold) 
          .onClick(() => { 
            taskpool.cancel(this.task); 
          }) 
      } 
    } 
    .width('100%') 
    .height('100%') 
  } 
}

在3秒内，取消任务，不会存在“taskpool run finish”日志打印。3秒外，就会存在“taskpool run finish”日志打印，此时，在根据this.task变量来取消，则会“The task does not exist when it is canceled”。
可以增加判断，如：

taskpool.execute(this.task).then((value: Object) => { 
  hilog.info(0x0000, 'testTag', '%{public}s', 'taskpool run finish'); 
  this.task = undefined; 
}) 
if (this.task != undefined) { 
  taskpool.cancel(this.task); 
}