[ROCKETMQ-167] namesrv RouteInfoManager scanNotActiveBroker have the Thread competition

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Feedback Received
• Affects Version/s: 4.0.0-incubating
• Fix Version/s: 4.2.0
• Component/s: rocketmq-namesrv
• Assignee: Xinyu Zhou
• Reporter: zhaoziyan
• Created: 07/Apr/17 08:14
• Updated: 13/Dec/17 11:57
• Resolved: 13/Dec/17 11:57

Description

    public void scanNotActiveBroker() {
        Iterator<Entry<String, BrokerLiveInfo>> it = this.brokerLiveTable.entrySet().iterator();
        while (it.hasNext()) {
            Entry<String, BrokerLiveInfo> next = it.next();
            long last = next.getValue().getLastUpdateTimestamp();
            if ((last + BROKER_CHANNEL_EXPIRED_TIME) < System.currentTimeMillis()) {
                RemotingUtil.closeChannel(next.getValue().getChannel());
                it.remove();
                log.warn("The broker channel expired, {} {}ms", next.getKey(), BROKER_CHANNEL_EXPIRED_TIME);
                this.onChannelDestroy(next.getKey(), next.getValue().getChannel());
            }
        }
    }

scanNotActiveBroker dont have the writelock ,but it is modify the brokerLiveTable and Iterator the brokerLiveTable .
NSScheduledThread and nettyeventExcutor Thread have the competition.
The scanNotActiveBroker may throw
java.util.ConcurrentModificationException: null
and nevel run again