[ http://issues.apache.org/jira/browse/HADOOP-367?page=all ]
Benjamin Reed updated HADOOP-367:
---------------------------------
Attachment: f.patch
Arg! It seems that public static methods on non-public classes cannot be called
with reflection :( So I took a different approach that is simpler and less
code. (This patch removes 132 lines and adds 18.)
I noticed that all of the factories simply created new objects. So now the
WritableFactories.newInstance method finds the factory that corresponds to the
package of the class and lets that factory create it. This means that there
needs to be a WriteableFactory for each package that has Writables. This lowers
the number of overall factories while adding one visible factory per package.
It also simplifies the Writables since they don't need to worry about factories
anymore.
> Static blocks do not automatically run when a class is loaded in Java 5.0
> -------------------------------------------------------------------------
>
> Key: HADOOP-367
> URL: http://issues.apache.org/jira/browse/HADOOP-367
> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Affects Versions: 0.4.0
> Environment: Java 5.0
> Reporter: Benjamin Reed
> Attachments: f.patch
>
>
> There seems to be a change that happened between 1.4 and 1.5 with respect to
> static initializers. I can't find this documented, but I can reproduce with a
> very simple program. Basically, a static initializer is not called unless a
> static member/method of the class is accessed or an instance is created. This
> is actually what the JLS says, but until 1.5 the static initializers ran when
> the class was loaded. Note that this behavior only occurs when running with
> the 1.5 JRE AND compiling for 1.5.
> For many Writables this isn't an issue, so the fallback behavior of the
> WritableFactory works, but Block is package private, so loadEdits fails when
> called from org.apache.hadoop.io.ArrayWritable.readFields() yielding the
> following trace:
> Caused by: java.lang.RuntimeException: java.lang.IllegalAccessException:
> Class org.apache.hadoop.io.WritableFactories can not access a member of class
> org.apache.hadoop.dfs.Block with modifiers "public"
> at
> org.apache.hadoop.io.WritableFactories.newInstance(WritableFactories.java:49)
> at
> org.apache.hadoop.io.ArrayWritable.readFields(ArrayWritable.java:81)
> at org.apache.hadoop.dfs.FSDirectory.loadFSEdits(FSDirectory.java:532)
> at org.apache.hadoop.dfs.FSDirectory.loadFSImage(FSDirectory.java:470)
> at org.apache.hadoop.dfs.FSDirectory.<init>(FSDirectory.java:307)
> at org.apache.hadoop.dfs.FSNamesystem.<init>(FSNamesystem.java:177)
> at org.apache.hadoop.dfs.NameNode.<init>(NameNode.java:91)
> at org.apache.hadoop.dfs.NameNode.<init>(NameNode.java:84)
> at org.apache.hadoop.dfs.NameNode.main(NameNode.java:491)
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