checkOfflineNodes() {
		if (this.opts.disableOfflineNodeRemoving || !this.opts.cleanOfflineNodesTimeout) return;

		const now = Math.round(process.uptime());
		this.registry.nodes.toArray().forEach(node => {
			if (node.local || node.available) return;
			if (!node.lastHeartbeatTime) {
				// Not received the first
				node.lastHeartbeatTime = now;
				return;
			}

			if (now - node.lastHeartbeatTime > this.opts.cleanOfflineNodesTimeout) {
				this.logger.warn(
					`Removing offline '${node.id}' node from registry because it hasn't submitted heartbeat signal for 10 minutes.`
				);
				this.registry.nodes.delete(node.id);
			}
		});
	}
Check offline nodes. Remove which is older than 10 minutes.