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https://issues.apache.org/jira/browse/HBASE-4946?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrei Dragomir updated HBASE-4946:
-----------------------------------
Status: Patch Available (was: Open)
> HTable.coprocessorExec (and possibly coprocessorProxy) does not work with
> dynamically loaded coprocessors (from hdfs or local system), because the RPC
> system tries to deserialize an unknown class.
> -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-4946
> URL: https://issues.apache.org/jira/browse/HBASE-4946
> Project: HBase
> Issue Type: Bug
> Components: coprocessors
> Affects Versions: 0.92.0
> Reporter: Andrei Dragomir
> Attachments: HBASE-4946.patch
>
>
> Loading coprocessors jars from hdfs works fine. I load it from the shell,
> after setting the attribute, and it gets loaded:
> {noformat}
> INFO org.apache.hadoop.hbase.regionserver.HRegion: Setting up tabledescriptor
> config now ...
> INFO org.apache.hadoop.hbase.coprocessor.CoprocessorHost: Class
> com.MyCoprocessorClass needs to be loaded from a file -
> hdfs://localhost:9000/coproc/rt- >0.0.1-SNAPSHOT.jar.
> INFO org.apache.hadoop.hbase.coprocessor.CoprocessorHost: loadInstance:
> com.MyCoprocessorClass
> INFO org.apache.hadoop.hbase.regionserver.RegionCoprocessorHost:
> RegionEnvironment createEnvironment
> DEBUG org.apache.hadoop.hbase.regionserver.HRegion: Registered protocol
> handler: region=t1,,1322572939753.6409aee1726d31f5e5671a59fe6e384f.
> protocol=com.MyCoprocessorClassProtocol
> INFO org.apache.hadoop.hbase.regionserver.RegionCoprocessorHost: Load
> coprocessor com.MyCoprocessorClass from HTD of t1 successfully.
> {noformat}
> The problem is that this coprocessors simply extends BaseEndpointCoprocessor,
> with a dynamic method. When calling this method from the client with
> HTable.coprocessorExec, I get errors on the HRegionServer, because the call
> cannot be deserialized from writables.
> The problem is that Exec tries to do an "early" resolve of the coprocessor
> class. The coprocessor class is loaded, but it is in the context of the
> HRegionServer / HRegion. So, the call fails:
> {noformat}
> 2011-12-02 00:34:17,348 ERROR org.apache.hadoop.hbase.io.HbaseObjectWritable:
> Error in readFields
> java.io.IOException: Protocol class com.MyCoprocessorClassProtocol not found
> at org.apache.hadoop.hbase.client.coprocessor.Exec.readFields(Exec.java:125)
> at
> org.apache.hadoop.hbase.io.HbaseObjectWritable.readObject(HbaseObjectWritable.java:575)
> at org.apache.hadoop.hbase.ipc.Invocation.readFields(Invocation.java:105)
> at
> org.apache.hadoop.hbase.ipc.HBaseServer$Connection.processData(HBaseServer.java:1237)
> at
> org.apache.hadoop.hbase.ipc.HBaseServer$Connection.readAndProcess(HBaseServer.java:1167)
> at
> org.apache.hadoop.hbase.ipc.HBaseServer$Listener.doRead(HBaseServer.java:703)
> at
> org.apache.hadoop.hbase.ipc.HBaseServer$Listener$Reader.doRunLoop(HBaseServer.java:495)
> at
> org.apache.hadoop.hbase.ipc.HBaseServer$Listener$Reader.run(HBaseServer.java:470)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
> at java.lang.Thread.run(Thread.java:680)
> Caused by: java.lang.ClassNotFoundException: com.MyCoprocessorClassProtocol
> at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
> at java.security.AccessController.doPrivileged(Native Method)
> at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
> at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
> at java.lang.Class.forName0(Native Method)
> at java.lang.Class.forName(Class.java:247)
> at
> org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:943)
> at org.apache.hadoop.hbase.client.coprocessor.Exec.readFields(Exec.java:122)
> ... 10 more
> {noformat}
> Probably the correct way to fix this is to make Exec really smart, so that it
> knows all the class definitions loaded in CoprocessorHost(s).
> I created a small patch that simply doesn't resolve the class definition in
> the Exec, instead passing it as string down to the HRegion layer. This layer
> knows all the definitions, and simply loads it by name.
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