Why does the lease mechanism of ETCD not pop expired leases directly from the heap？

[GTianLuo]

The lease mechanism of etcd does not perform a pop operation directly when detecting an expired lease. Instead, it extends the expiration time of the lease and reorganizes the heap, and only pops the expired lease from the heap during the next round of detection。What is the reason for doing this?

func (le *lessor) expireExists() (l *Lease, next bool) {
	if le.leaseExpiredNotifier.Len() == 0 {
		return nil, false
	}

	item := le.leaseExpiredNotifier.Peek()
	l = le.leaseMap[item.id]
	if l == nil {
		// lease has expired or been revoked
		// no need to revoke (nothing is expiry)
		le.leaseExpiredNotifier.Unregister() // O(log N)
		return nil, true
	}
	now := time.Now()
	if now.Before(item.time) /* item.time: expiration time */ {
		// Candidate expirations are caught up, reinsert this item
		// and no need to revoke (nothing is expiry)
		return nil, false
	}

	// recheck if revoke is complete after retry interval
	item.time = now.Add(le.expiredLeaseRetryInterval)
	le.leaseExpiredNotifier.RegisterOrUpdate(item)
	return l, false
}