当调用出现超时时，不能稳定的触发熔断

我针对RT Degrade demo中的例子做了一些修改，前50次调用才会触发sleep，并增加到5s，Thread.sleep(5000)，而且增加了success的统计,输出如下。

1549091434879, total:7280, pass:58, block:7271,succcess:9 1549091435884, total:8901, pass:0, block:8901,succcess:0 1549091436887, total:8732, pass:0, block:8732,succcess:0 1549091437890, total:8823, pass:0, block:8823,succcess:0 1549091438891, total:8776, pass:0, block:8776,succcess:0 1549091439896, total:15951, pass:0, block:15902,succcess:49 1549091440899, total:17133, pass:0, block:17133,succcess:0 1549091441902, total:17193, pass:0, block:17193,succcess:0 1549091442903, total:16908, pass:0, block:16908,succcess:0 1549091443908, total:17125, pass:0, block:17125,succcess:0 1549091444910, total:16841, pass:58, block:16784,succcess:58 1549091445912, total:16935, pass:0, block:16935,succcess:0 1549091446916, total:16960, pass:0, block:16959,succcess:0 1549091447919, total:17144, pass:0, block:17144,succcess:0 1549091448919, total:16942, pass:0, block:16944,succcess:0 1549091449921, total:17033, pass:0, block:17031,succcess:0 1549091450924, total:17171, pass:0, block:17172,succcess:0 1549091451926, total:17217, pass:0, block:17216,succcess:0 1549091452930, total:17203, pass:0, block:17203,succcess:0 1549091453933, total:17075, pass:0, block:17075,succcess:0 1549091454938, total:17072, pass:15169, block:1903,succcess:15169 1549091455942, total:17000, pass:17000, block:0,succcess:17000

在使用时，由于网络波动，或者服务端的意外的情况，或者一些锁问题等等，会导致一段时间的调用超时。但Sentinel的熔断策略会导致整体服务长期不可用。 明明第1秒就恢复的问题，导致了20s的不可用。

关于这个问题，有没有好的方法解决？

import com.alibaba.csp.sentinel.Entry; import com.alibaba.csp.sentinel.SphU; import com.alibaba.csp.sentinel.slots.block.BlockException; import com.alibaba.csp.sentinel.slots.block.RuleConstant; import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRule; import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRuleManager; import com.alibaba.csp.sentinel.util.TimeUtil; import org.junit.Test;

import java.util.ArrayList; import java.util.List; import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicInteger;

/** * @author zhaohaifeng * @date 2019-02-02 */ public class SentinelTest {

private static final String KEY = "abc";

private static AtomicInteger pass = new AtomicInteger();
private static AtomicInteger success = new AtomicInteger();
private static AtomicInteger block = new AtomicInteger();
private static AtomicInteger total = new AtomicInteger();

private static volatile boolean stop = false;
private static final int threadCount = 100;
private static int seconds = 60 + 40;

public static void main(String[] args) throws Exception {

    tick();
    initDegradeRule();

    for (int i = 0; i < threadCount; i++) {
        Thread entryThread = new Thread(new Runnable() {

            @Override
            public void run() {
                while (true) {
                    Entry entry = null;
                    try {
                        TimeUnit.MILLISECONDS.sleep(5);
                        entry = SphU.entry(KEY);
                        // token acquired
                        int p = pass.incrementAndGet();
                        // sleep 600 ms, as rt
                        if (p < 50) {
                            TimeUnit.MILLISECONDS.sleep(5000);
                        }
                        success.incrementAndGet();
                    } catch (Exception e) {
                        block.incrementAndGet();
                    } finally {
                        total.incrementAndGet();
                        if (entry != null) {
                            entry.exit();
                        }
                    }
                }
            }

        });
        entryThread.setName("working-thread");
        entryThread.start();
    }
}

private static void initDegradeRule() {
    List<DegradeRule> rules = new ArrayList<DegradeRule>();
    DegradeRule rule = new DegradeRule();
    rule.setResource(KEY);
    // set threshold rt, 10 ms
    rule.setCount(10);
    rule.setGrade(RuleConstant.DEGRADE_GRADE_RT);
    rule.setTimeWindow(10);
    rules.add(rule);
    DegradeRuleManager.loadRules(rules);
}

private static void tick() {
    Thread timer = new Thread(new TimerTask());
    timer.setName("sentinel-timer-task");
    timer.start();
}

static class TimerTask implements Runnable {

    @Override
    public void run() {
        long start = System.currentTimeMillis();
        System.out.println("begin to statistic!!!");
        long oldTotal = 0;
        long oldPass = 0;
        long oldBlock = 0;
        long oldSuccess = 0;

        while (!stop) {
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
            }

            long globalTotal = total.get();
            long oneSecondTotal = globalTotal - oldTotal;
            oldTotal = globalTotal;

            long globalPass = pass.get();
            long oneSecondPass = globalPass - oldPass;
            oldPass = globalPass;

            long globalBlock = block.get();
            long oneSecondBlock = globalBlock - oldBlock;
            oldBlock = globalBlock;

            long globalSuccess = success.get();
            long oneSecondSuccess = globalSuccess - oldSuccess;
            oldSuccess = globalSuccess;

            System.out.println(TimeUtil.currentTimeMillis() + ", total:" + oneSecondTotal
                    + ", pass:" + oneSecondPass + ", block:" + oneSecondBlock+",succcess:"+oneSecondSuccess);

            if (seconds-- <= 0) {
                stop = true;
            }
        }

        long cost = System.currentTimeMillis() - start;
        System.out.println("time cost: " + cost + " ms");
        System.out.println("total:" + total.get() + ", pass:" + pass.get()
                + ", block:" + block.get());
        System.exit(0);
    }
}

}

原提问者GitHub用户zhaohaifeng