Java执行器。scheduleAtFixedRate累加延迟

我遇到了一些执行人延迟的问题。我的线程如下所示:

public void run() {
    logger.log("Starting " + tso.getName() + " for " + dataType);
    List<String[]> allRows = new ArrayList<String[]>();
    String[] lastRow;
    LocalDateTime lastDate;;
    LocalDateTime lastQuarterHour;
    while (true) {
        try {
            // Make attempt to take CSV data for today. If there is no data wait several seconds and try again
            allRows = getCSVRows();
            if (allRows == null || allRows.isEmpty()) {
                logger.log("Sleeping thread due to empty list for TSO " + tso.getName() + " and data type " + dataType);
                Thread.sleep(MILISECONDS_TO_WAIT);
                continue;
            }
            lastRow = allRows.get(allRows.size() - 1);
            lastDate = convertStringToUTC(lastRow[0] + " " + lastRow[2]);
            lastQuarterHour = takeLastQuorterHourTime();

            // If CSV data is available take the last record if it is before last quarter hour wait SEVERAL seconds and try again
            if (lastDate.isBefore(lastQuarterHour)) {
                logger.log("Sleeping due to lack of information for the current quarter for TSO " + tso.getName() + " and data type " + dataType);
                Thread.sleep(MILISECONDS_TO_WAIT);
            } else {
                break;
            }
        } catch (InterruptedException e) {
            logger.log(e.getMessage());
        }

    }
  }
}

我第一次运行线程时,延迟是可以的,但当线程休眠2或3次时,下一个线程周期开始时的延迟不是中定义的:

executor.scheduleAtFixedRate(extractorThread, 0, WAIT_INTERVAL_MINUTES, TimeUnit.SECONDS);