序

ribbon有个参数可以用来调整刷新server list的时间间隔参数。

ServerListRefreshInterval

ribbon-core-2.2.0-sources.jar!/com/netflix/client/config/CommonClientConfigKey.java

public static final IClientConfigKey
    
      ServerListRefreshInterval = new CommonClientConfigKey
     
      ("ServerListRefreshInterval"){};
     
    

PollingServerListUpdater

ribbon-loadbalancer-2.2.0-sources.jar!/com/netflix/loadbalancer/PollingServerListUpdater.java

private static long getRefreshIntervalMs(IClientConfig clientConfig) {        return clientConfig.get(CommonClientConfigKey.ServerListRefreshInterval, LISTOFSERVERS_CACHE_REPEAT_INTERVAL);    }        @Override    public synchronized void start(final UpdateAction updateAction) {        if (isActive.compareAndSet(false, true)) {            final Runnable wrapperRunnable = new Runnable() {                @Override                public void run() {                    if (!isActive.get()) {                        if (scheduledFuture != null) {                            scheduledFuture.cancel(true);                        }                        return;                    }                    try {                        updateAction.doUpdate();                        lastUpdated = System.currentTimeMillis();                    } catch (Exception e) {                        logger.warn("Failed one update cycle", e);                    }                }            };            scheduledFuture = getRefreshExecutor().scheduleWithFixedDelay(                    wrapperRunnable,                    initialDelayMs,                    refreshIntervalMs,                    TimeUnit.MILLISECONDS            );        } else {            logger.info("Already active, no-op");        }    }

DynamicServerListLoadBalancer

ribbon-loadbalancer-2.2.0-sources.jar!/com/netflix/loadbalancer/DynamicServerListLoadBalancer.java

protected final ServerListUpdater.UpdateAction updateAction = new ServerListUpdater.UpdateAction() {        @Override        public void doUpdate() {            updateListOfServers();        }    };@VisibleForTesting    public void updateListOfServers() {        List
    
      servers = new ArrayList
     
      ();        if (serverListImpl != null) {            servers = serverListImpl.getUpdatedListOfServers();            LOGGER.debug("List of Servers for {} obtained from Discovery client: {}",                    getIdentifier(), servers);            if (filter != null) {                servers = filter.getFilteredListOfServers(servers);                LOGGER.debug("Filtered List of Servers for {} obtained from Discovery client: {}",                        getIdentifier(), servers);            }        }        updateAllServerList(servers);    }/**     * Update the AllServer list in the LoadBalancer if necessary and enabled     *      * @param ls     */    protected void updateAllServerList(List
      
        ls) {        // other threads might be doing this - in which case, we pass        if (serverListUpdateInProgress.compareAndSet(false, true)) {            for (T s : ls) {                s.setAlive(true); // set so that clients can start using these                                  // servers right away instead                // of having to wait out the ping cycle.            }            setServersList(ls);            super.forceQuickPing();            serverListUpdateInProgress.set(false);        }    }
      
     
    

这里设置list的时候，顺带调用了forceQuickPing()方法

BaseLoadBalancer#forceQuickPing

ribbon-loadbalancer-2.2.0-sources.jar!/com/netflix/loadbalancer/BaseLoadBalancer.java

/*     * Force an immediate ping, if we're not currently pinging and don't have a     * quick-ping already scheduled.     */    public void forceQuickPing() {        if (canSkipPing()) {            return;        }        if (logger.isDebugEnabled()) {            logger.debug("LoadBalancer:  forceQuickPing invoked");        }        Pinger ping = new Pinger(pingStrategy);        try {            ping.runPinger();        } catch (Throwable t) {            logger.error("Throwable caught while running forceQuickPing() for "                    + name, t);        }    }