延迟任务回调onWorkStart和onWorkStop是运行在主线程吗

{ 
  "module": { 
  "extensionAbilities": [ 
      { 
        "name": "WorkTest", 
        "srcEntrance": "./ets/workAbility/WorkTest.ets", 
        "label": "$string:WorkSchedulerExtensionAbility_label", 
        "description": "$string:WorkSchedulerExtensionAbility_desc", 
        "type": "workScheduler" 
      } 
    ] 
  } 
}