[HBASE-4980] Null pointer exception in HBaseClient receiveResponse

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.92.0
• Fix Version/s: 0.92.0
• Component/s: Client
• Hadoop Flags: Reviewed
• Assignee: Shrijeet Paliwal
• Reporter: Shrijeet Paliwal
• Created: 08/Dec/11 04:00
• Updated: 20/Nov/15 11:52
• Resolved: 08/Dec/11 22:23

Description

Relevant Stack trace:

2011-11-30 13:10:26,557 [IPC Client (47) connection to xx.xx.xx/172.22.4.68:60020 from an unknown user] WARN org.apache.hadoop.ipc.HBaseClient - Unexpected exception receiving call responses
java.lang.NullPointerException
>-at org.apache.hadoop.hbase.ipc.HBaseClient$Connection.receiveResponse(HBaseClient.java:583)
>-at org.apache.hadoop.hbase.ipc.HBaseClient$Connection.run(HBaseClient.java:511)

  if (LOG.isDebugEnabled())
          LOG.debug(getName() + " got value #" + id);
        Call call = calls.remove(id);
        // Read the flag byte
        byte flag = in.readByte();
        boolean isError = ResponseFlag.isError(flag);
        if (ResponseFlag.isLength(flag)) {
          // Currently length if present is unused.
          in.readInt();
        }
        int state = in.readInt(); // Read the state.  Currently unused.
        if (isError) {
          //noinspection ThrowableInstanceNeverThrown
          call.setException(new RemoteException( WritableUtils.readString(in),
              WritableUtils.readString(in)));
        } else {

This line

Call call = calls.remove(id);

may return a null 'call'. It is so because if you have rpc timeout enable, we proactively clean up other calls which have expired their lifetime along with the call for which socket timeout exception happend.