[jira] [Created] (HDFS-16704) Datanode return empty response instead of NPE for GetVolumeInfo during restarting

["ZanderXu (Jira)" <ji...@apache.org>]

ZanderXu created HDFS-16704:
-------------------------------

             Summary: Datanode return empty response instead of NPE for GetVolumeInfo during restarting
                 Key: HDFS-16704
                 URL: https://issues.apache.org/jira/browse/HDFS-16704
             Project: Hadoop HDFS
          Issue Type: Improvement
            Reporter: ZanderXu
            Assignee: ZanderXu


During datanode starting, I found some NPE in logs:

 
{code:java}
Caused by: java.lang.NullPointerException: Storage not yet initialized
    at org.apache.hadoop.thirdparty.com.google.common.base.Preconditions.checkNotNull(Preconditions.java:899)
    at org.apache.hadoop.hdfs.server.datanode.DataNode.getVolumeInfo(DataNode.java:3533)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:72)
    at sun.reflect.GeneratedMethodAccessor7.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:276)
    at com.sun.jmx.mbeanserver.ConvertingMethod.invokeWithOpenReturn(ConvertingMethod.java:193)
    at com.sun.jmx.mbeanserver.ConvertingMethod.invokeWithOpenReturn(ConvertingMethod.java:175) {code}
 

 

Because the storage of datanode not yet initialized when we trying to get metrics of datanode, and related code as below:
{code:java}
@Override // DataNodeMXBean
public String getVolumeInfo() {
  Preconditions.checkNotNull(data, "Storage not yet initialized");
  return JSON.toString(data.getVolumeInfoMap());
} {code}
The logic is ok, but I feel that more reasonable logic should be return a empty response instead of NPE, because InfoServer will be started before initBlockPool.



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