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https://issues.apache.org/jira/browse/HADOOP-309?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12466637
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navychen commented on HADOOP-309:
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here is my solution, does it okay for this bug?
> 1. Remove the "/logs" context when no "hadoop.log.dir" property is defined.
I changed StatusHttpServer.java at line 73-79
73 // set up the context for "/logs/"
74 HttpContext logContext = new HttpContext();
75 logContext.setContextPath("/logs/*");
76 String logDir = System.getProperty("hadoop.log.dir");
77 logContext.setResourceBase(logDir);
78 logContext.addHandler(new ResourceHandler());
79 webServer.addContext(logContext);
to
73 // set up the context for "/logs/" if "hadoop.log.dir" property is
defined.
74 String logDir = System.getProperty("hadoop.log.dir");
75 if( logDir != null ) {
76 HttpContext logContext = new HttpContext();
77 logContext.setContextPath("/logs/*");
78 logContext.setResourceBase(logDir);
79 logContext.addHandler(new ResourceHandler());
80 webServer.addContext(logContext);
81 }
And it works okay, but there has a little impact that user cannot visit
"/logs/" at web UI.
> 2. See if we can get the value from log4j via the jakarta commons logging
> api. It looks like there might be routines that will work.
I does not find a api to get these value at Jakarta commons logging api
documents:
http://jakarta.apache.org/commons/logging/apidocs/index.html
I am puzzle that how to do this, because log4j.properties is read by log4j lib
automatically,
For hadoop framework, it don't know or should don't know what log library it
use, so is it not good to
Get value from log4j?
> Konstantin:
1, Even if I get through this I get yet another NullPointerException.Now
because webapps resource is not defined.
This is because he did not add base directory of hadoop that contains "webapp"
directory into CLASSPATH,
I insert two lines to StatusHttpServer.java to throw "not found webapps"
exception to user, Is this a good way to fix it?
154 private static String getWebAppsPath() throws IOException {
155 URL url =
StatusHttpServer.class.getClassLoader().getResource("webapps");
156 if( url == null )
157 throw new IOException("webapps not found in CLASSPATH");
158 String path = url.getPath();
if webapps resource is not defined, It seems that could not set a default value
for it or return null,
because webAppContext member of StatusHttpServer should be initialized with
webapps resource path for many functions need to access it,
so maybe throw a intelligible exception to user is a better way.
> 2, trying to start the Namenode directly without using any scripts.
To resolve this problem and let user can start NameNode without any scripts,
can run as these steps in hadoop base directory:
1, export CLASSPATH=$CLASSPATH:./build/:./build/classes/:./:./conf/
2, export CLASSPATH=$CLASSPATH:`ls lib/*.jar | cat | tr '\n' :`
3, export CLASSPATH=$CLASSPATH:`ls lib/jetty-ext/*.jar | cat | tr '\n' :`
4, java org.apache.hadoop.dfs.NameNode
> NullPointerException in StatusHttpServer
> ----------------------------------------
>
> Key: HADOOP-309
> URL: https://issues.apache.org/jira/browse/HADOOP-309
> Project: Hadoop
> Issue Type: Bug
> Components: mapred
> Affects Versions: 0.3.2
> Reporter: Konstantin Shvachko
> Assigned To: Owen O'Malley
> Priority: Minor
>
> The NullPointerException happens in the constructor of StatusHttpServer
> because the System property "hadoop.log.dir" is undefined.
> I see it trying to start the Namenode directly without using any scripts.
> Exception in thread "main" java.lang.NullPointerException
> at org.mortbay.util.Resource.newResource(Resource.java:99)
> at
> org.mortbay.http.ResourceCache.setResourceBase(ResourceCache.java:140)
> at org.mortbay.http.HttpContext.setResourceBase(HttpContext.java:2207)
> at
> org.apache.hadoop.mapred.StatusHttpServer.<init>(StatusHttpServer.java:66)
> at org.apache.hadoop.dfs.FSNamesystem.<init>(FSNamesystem.java:172)
> at org.apache.hadoop.dfs.NameNode.<init>(NameNode.java:97)
> at org.apache.hadoop.dfs.NameNode.<init>(NameNode.java:88)
> at org.apache.hadoop.dfs.NameNode.main(NameNode.java:496)
> In general I think the sources should not rely on the system properties and
> environment variables defined in hadoop scripts.
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