问rxjs :在我发送的第一个set上获取重复的http请求

EN

let requests: Observable<ResourceResponse>[] = initRequests(this.durationService.resourceDataDuration)
    timer(0, environment.dashboard.frequency)
      .pipe(
        takeUntil(this.destroy),
        startWith(0),
        switchMap(() => forkJoin(requests))
      )
      .subscribe((responsesArr: ResourceResponse[]) => {
        this.updateBegin()
        for (const response of responsesArr) {
          this.durationService.resourceDurationHandler.setPresentedDataRanges(
            response,
            this.durationService.resourceDataDuration,
            this.durationService.resourcePresnetedDataDurations
          )
          this.updateMany(response.Resource, response.Response, true)
        }
        this.updateEnd()
        requests = initRequests(this.durationService.resourceDataDuration)
      })