这个load操作发生在启动broker的时候。

所以我们直接进入DefaultMessageStore的load()方法：

/**     * 加载数据     *     * @throws IOException     */    public boolean load() {        boolean result = true;        try {            boolean lastExitOK = !this.isTempFileExist();            log.info("last shutdown {}", (lastExitOK ? "normally" : "abnormally"));            // load 定时进度            // 这个步骤要放置到最前面，从CommitLog里Recover定时消息需要依赖加载的定时级别参数            // slave依赖scheduleMessageService做定时消息的恢复            if (null != scheduleMessageService) {                result = result && this.scheduleMessageService.load();            }            // load Commit Log            result = result && this.commitLog.load();            // load Consume Queue            result = result && this.loadConsumeQueue();            if (result) {                this.storeCheckpoint =                        new StoreCheckpoint(StorePathConfigHelper.getStoreCheckpoint(this.messageStoreConfig.getStorePathRootDir()));                this.indexService.load(lastExitOK);                // 尝试恢复数据                this.recover(lastExitOK);                log.info("load over, and the max phy offset = {}", this.getMaxPhyOffset());            }        } catch (Exception e) {            log.error("load exception", e);            result = false;        }        if (!result) {            this.allocateMapedFileService.shutdown();        }        return result;    }

 

新开了一篇来写：http://www.cnblogs.com/guazi/p/6836112.html