子线程指令重排

CountDownLatch countDownLatch = new CountDownLatch(1);

try{
    boolean anotherDay = checkAnotherDay();
    try{
        if(anotherDay) {
            String logUrlYestoday = logUrl;
            int index = logUrlYestoday.lastIndexOf(".");
            StringBuilder stringBuilder = new StringBuilder(100);
            stringBuilder.append(logUrlYestoday.substring(0, index+1)).append(dateIbFormate.format(lastTime)).append(".log");

            int res = readLogFile(stringBuilder.toString(), false);
            if(res == 0) {
                logger.info("read yesterday success");
            } else {
                logger.error("read yesterday error, {}", res);
            }
        }
    } catch (Exception e) {
        logger.error(e.getMessage(), e);
    } finally {
        countDownLatch.countDown();
    }

    countDownLatch.await();

    readLogFile(logUrl, true);

} catch (Exception e) {
    logger.error(e.getMessage(), e);
}

　　

在未使用CountDownLatch前，有出现最后一行

readLogFile

 

的数据先于前面的代码数据执行插入操作了，故为了确保数据有序性，加入CountDownLatch

 

性质有点像：https://www.cnblogs.com/silyvin/p/9106641.html