74行 int offsetWeight = random.nextInt(totalWeight);//这里totalWeight是没有经过warmup降权的值的和
78 offsetWeight -= getWeight(invokers.get(leastIndex), invocation);//这个是经过warmup降权的。

当服务刚启动，经过warmup降权后的getWeight返回的值，可能经过leastCount次循环后，还是offsetWeight >0
造成选不到invoker
for (int i = 0; i < leastCount; i++) {
int leastIndex = leastIndexs[i];
offsetWeight -= getWeight(invokers.get(leastIndex), invocation);
if (offsetWeight <= 0)
return invokers.get(leastIndex);
}