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https://issues.apache.org/jira/browse/HDFS-14647?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16888510#comment-16888510
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Ayush Saxena commented on HDFS-14647:
-------------------------------------
{quote}For the specific question about why I use getter, it is for testing
purposes, with the getter I can mock the returning result.
{quote}
For test purpose, I don't think it is a good idea to do anything like this
which isn't required as part of the code, which can even have a minor impact.
Certainly not in the core part of NN. May be need to find some other way to
test.
{quote}Even if I add one exception, it will be like this, thus it feels a
little redundant to do it the same way.
{quote}
Two things : Firstly HDFS believes in fail-fast, when you know any how you are
going to fail latter, fail here only.
Secondly : We don't have control on future execution of the codes, if in
future, the code part which you are relying on to throw exception, gets tweaked
for some other use case, this shall get affected. Better we stay independent.
Just my opinion. May wait for some other opinions. :)
> NPE during secure namenode startup
> ----------------------------------
>
> Key: HDFS-14647
> URL: https://issues.apache.org/jira/browse/HDFS-14647
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs
> Affects Versions: 2.8.2
> Reporter: Fengnan Li
> Assignee: Fengnan Li
> Priority: Minor
> Attachments: HDFS-14647-trunk.001.patch, HDFS-14647.001.patch
>
>
> In secure HDFS, during Namenode loading fsimage, when hitting Namenode
> through the REST API, below exception would be thrown out. (This is in
> version 2.8.2)
> {quote}org.apache.hadoop.hdfs.web.resources.ExceptionHandler:
> INTERNAL_SERVER_ERROR
> java.lang.NullPointerException
> at
> org.apache.hadoop.hdfs.server.common.JspHelper.getTokenUGI(JspHelper.java:283)
> at org.apache.hadoop.hdfs.server.common.JspHelper.getUGI(JspHelper.java:226)
> at
> org.apache.hadoop.hdfs.web.resources.UserProvider.getValue(UserProvider.java:54)
> at
> org.apache.hadoop.hdfs.web.resources.UserProvider.getValue(UserProvider.java:42)
> at
> com.sun.jersey.server.impl.inject.InjectableValuesProvider.getInjectableValues(InjectableValuesProvider.java:46)
> at
> com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$EntityParamInInvoker.getParams(AbstractResourceMethodDispatchProvider.java:153)
> at
> com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ResponseOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:203)
> at
> com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)
> at
> com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:288)
> at
> com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
> at
> com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108)
> at
> com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
> at
> com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84)
> at
> com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1469)
> at
> com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1400)
> at
> com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1349)
> at
> com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1339)
> at
> com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:416)
> at
> com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:537)
> at
> com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:699)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
> at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
> at
> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1221)
> at org.apache.hadoop.hdfs.web.AuthFilter.doFilter(AuthFilter.java:87)
> at
> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
> at
> org.apache.hadoop.http.HttpServer2$QuotingInputFilter.doFilter(HttpServer2.java:1353)
> at
> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
> at org.apache.hadoop.http.NoCacheFilter.doFilter(NoCacheFilter.java:45)
> at
> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
> at org.apache.hadoop.http.NoCacheFilter.doFilter(NoCacheFilter.java:45)
> at
> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
> at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:399)
> at
> org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
> at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
> at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
> at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:450)
> at
> org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
> at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
> at org.mortbay.jetty.Server.handle(Server.java:326)
> at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
> at
> org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:928)
> at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:549)
> at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
> at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
> at
> org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)
> at
> org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
> {quote}
> This is because during this phase, namesystem hasn't been initialized. In
> non-HA context, it can throw a RetriableException to let the client retry or
> simply throw other exception to make the client fail. In HA context, one
> possible solution is to throw StandbyException to let the client fail over to
> another namenode.
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