问Kotlin协程使用ViewPager在除第一个片段实例化之外的每个片段实例化上停止启动

EN

class MyViewModel : ViewModel() {

    private var _list = MutableLiveData<ArrayList<ListItem>>()
    val _list: LiveData<ArrayList<ListItem>>
        get() = _list

    fun refresh() = viewModelScope.launch {
        emitList()
    }

    private suspend fun emitList() = runIfBounded {
        withContext(Dispatchers.IO) {
            // run some database access code
            // post results to _list
        }
    }

}   

override fun onResume() {
    super.onResume()
    viewModel.refresh()
}