Zookeeper3.4.6之源码解读(二)

一、问题描述：

最近使用storm之后发现zookeeper总是出现警告，故此跟踪了一下源码，知道问题产生在哪里。警告信息如下：

2014-09-19 13:41:29,400 [myid:1] - WARN  [SyncThread:1:FileTxnLog@321] - fsync-ing the write ahead log in SyncThread:1 took 4575ms which will adversely effect operation latency. See the ZooKeeper troubleshooting guide

2014-09-19 13:41:30,453 [myid:1] - WARN  [QuorumPeer[myid=1]/0:0:0:0:0:0:0:0:2181:Follower@89] - Exception when following the leader

java.net.SocketTimeoutException: Read timed out

at java.net.SocketInputStream.socketRead0(Native Method)

at java.net.SocketInputStream.read(SocketInputStream.java:129)

at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)

at java.io.BufferedInputStream.read(BufferedInputStream.java:237)

at java.io.DataInputStream.readInt(DataInputStream.java:370)

at org.apache.jute.BinaryInputArchive.readInt(BinaryInputArchive.java:63)

二、问题定位：（FileTxnLog）

org.apache.zookeeper.server.persistence.FileTxnLog$FileTxnIterator.class

 /**

     * commit the logs. make sure that evertyhing hits the

     * disk

     */

    public synchronized void commit() throws IOException {

        if (logStream != null) {

            logStream.flush();

        }