[HDFS-13721] NPE in DataNode due to uninitialized DiskBalancer

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.2.0, 3.1.2
• Component/s: datanode, diskbalancer
• Target Version/s: 3.2.0
• Hadoop Flags: Reviewed
• Assignee: Xiao Chen
• Reporter: Xiao Chen
• Created: 05/Jul/18 20:11
• Updated: 10/Aug/18 21:10
• Resolved: 07/Jul/18 04:01

Description

2018-06-28 05:11:47,650 ERROR org.apache.hadoop.jmx.JMXJsonServlet: getting attribute DiskBalancerStatus of Hadoop:service=DataNode,name=DataNodeInfo threw an exception
javax.management.RuntimeMBeanException: java.lang.NullPointerException
 ***** TRACEBACK 4 *****
 at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.rethrow(DefaultMBeanServerInterceptor.java:839)
 at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.rethrowMaybeMBeanException(DefaultMBeanServerInterceptor.java:852)
 at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.getAttribute(DefaultMBeanServerInterceptor.java:651)
 at com.sun.jmx.mbeanserver.JmxMBeanServer.getAttribute(JmxMBeanServer.java:678)
 at org.apache.hadoop.jmx.JMXJsonServlet.writeAttribute(JMXJsonServlet.java:338)
 at org.apache.hadoop.jmx.JMXJsonServlet.listBeans(JMXJsonServlet.java:316)
 at org.apache.hadoop.jmx.JMXJsonServlet.doGet(JMXJsonServlet.java:210)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
 at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:848)
 at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1772)
 at org.apache.hadoop.http.lib.StaticUserWebFilter$StaticUserFilter.doFilter(StaticUserWebFilter.java:110)
 at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
 at org.apache.hadoop.http.HttpServer2$QuotingInputFilter.doFilter(HttpServer2.java:1537)
 at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
 at org.apache.hadoop.http.NoCacheFilter.doFilter(NoCacheFilter.java:45)
 at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
 at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:582)
 at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
 at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548)
 at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:226)
 at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1180)
 at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:512)
 at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
 at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1112)
 at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
 at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:119)
 at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134)
 at org.eclipse.jetty.server.Server.handle(Server.java:534)
 at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:320)
 at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251)
 at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:283)
 at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:108)
 at org.eclipse.jetty.io.SelectChannelEndPoint$2.run(SelectChannelEndPoint.java:93)
 at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.executeProduceConsume(ExecuteProduceConsume.java:303)
 at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceConsume(ExecuteProduceConsume.java:148)
 at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:136)
 at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:671)
 at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:589)
 at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
 at org.apache.hadoop.hdfs.server.datanode.DataNode.getDiskBalancerStatus(DataNode.java:3146)
 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:71)
 at sun.reflect.GeneratedMethodAccessor6.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:275)
 at com.sun.jmx.mbeanserver.ConvertingMethod.invokeWithOpenReturn(ConvertingMethod.java:193)
 at com.sun.jmx.mbeanserver.ConvertingMethod.invokeWithOpenReturn(ConvertingMethod.java:175)
 at com.sun.jmx.mbeanserver.MXBeanIntrospector.invokeM2(MXBeanIntrospector.java:117)
 at com.sun.jmx.mbeanserver.MXBeanIntrospector.invokeM2(MXBeanIntrospector.java:54)
 at com.sun.jmx.mbeanserver.MBeanIntrospector.invokeM(MBeanIntrospector.java:237)
 at com.sun.jmx.mbeanserver.PerInterface.getAttribute(PerInterface.java:83)
 at com.sun.jmx.mbeanserver.MBeanSupport.getAttribute(MBeanSupport.java:206)
 at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.getAttribute(DefaultMBeanServerInterceptor.java:647)
2018-06-28 05:12:08,400 ERROR org.apache.hadoop.jmx.JMXJsonServlet: getting attribute DiskBalancerStatus of Hadoop:service=DataNode,name=DataNodeInfo threw an exception
javax.management.RuntimeMBeanException: java.lang.NullPointerException

We have seen the above exception at datanode startup time. Should improve the NPE. Changing it to an IOE will also allow jmx to return '' correctly for getDiskBalancerStatus

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Issue Links

• duplicates: HDFS-13809 NPE in DataNode#getDiskBalancerStatus() when the DN is restarted