[HDFS-14088] RequestHedgingProxyProvider can throw NullPointerException when failover due to no lock on currentUsedProxy

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.3.0
• Component/s: hdfs-client
• Assignee: Yuxuan Wang
• Reporter: Yuxuan Wang
• Created: 19/Nov/18 09:46
• Updated: 14/Dec/18 19:38
• Resolved: 14/Dec/18 19:06

Description

if (currentUsedProxy != null) {
        try {
          Object retVal = method.invoke(currentUsedProxy.proxy, args);
          LOG.debug("Invocation successful on [{}]",
              currentUsedProxy.proxyInfo);

If a thread run try block and then other thread trigger a fail over calling method

@Override
  public synchronized void performFailover(T currentProxy) {
    toIgnore = this.currentUsedProxy.proxyInfo;
    this.currentUsedProxy = null;
  }

It will set currentUsedProxy to null, and the first thread can throw a NullPointerException.