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From "Ivan Veselovsky (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (IGNITE-4862) NPE in reading data from IGFS
Date Fri, 31 Mar 2017 10:18:41 GMT

    [ https://issues.apache.org/jira/browse/IGNITE-4862?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15949291#comment-15949291
] 

Ivan Veselovsky edited comment on IGNITE-4862 at 3/31/17 10:17 AM:
-------------------------------------------------------------------

The property `prefetchBlocks` must be set to non-zero value to reproduce the problem:
{code}
                <bean class="org.apache.ignite.configuration.FileSystemConfiguration">
                 .....
                    <property name="prefetchBlocks" value="32"/>
{code}

The following exception happens on the Ignite node at the same time: 
{code}
Exception in thread "igfs-#50%null%" java.lang.NullPointerException
	at org.apache.ignite.internal.processors.hadoop.impl.igfs.HadoopIgfsSecondaryFileSystemPositionedReadable.read(HadoopIgfsSecondaryFileSystemPositionedReadable.java:104)
	at org.apache.ignite.internal.processors.igfs.IgfsLazySecondaryFileSystemPositionedReadable.read(IgfsLazySecondaryFileSystemPositionedReadable.java:64)
	at org.apache.ignite.internal.processors.igfs.IgfsDataManager.secondaryDataBlock(IgfsDataManager.java:419)
	at org.apache.ignite.internal.processors.igfs.IgfsDataManager$4.applyx(IgfsDataManager.java:357)
	at org.apache.ignite.internal.processors.igfs.IgfsDataManager$4.applyx(IgfsDataManager.java:346)
	at org.apache.ignite.internal.util.lang.IgniteClosureX.apply(IgniteClosureX.java:38)
	at org.apache.ignite.internal.util.future.GridFutureChainListener.applyCallback(GridFutureChainListener.java:78)
	at org.apache.ignite.internal.util.future.GridFutureChainListener.access$000(GridFutureChainListener.java:30)
	at org.apache.ignite.internal.util.future.GridFutureChainListener$1.run(GridFutureChainListener.java:65)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)
{code}

The problem is that class `org.apache.ignite.internal.processors.hadoop.impl.igfs.HadoopIgfsSecondaryFileSystemPositionedReadable`
was designed fro single-threaded access, but in fact was accessed by multiple threads. That
lead to unexpected situation, when org.apache.ignite.internal.processors.hadoop.impl.igfs.HadoopIgfsSecondaryFileSystemPositionedReadable#in
returned null , that caused a bunch of further errors. 
Fixed by making HadoopIgfsSecondaryFileSystemPositionedReadable thread safe (underlying secondary
file system input stream has its own mechanisms to preserve consistency upon multithreaded
access.)


was (Author: iveselovskiy):
The following properties should be set to reproduce the problem:
{code}
                <bean class="org.apache.ignite.configuration.FileSystemConfiguration">
                    <property name="perNodeParallelBatchCount" value="16"/>
                    <property name="prefetchBlocks" value="32"/>
{code}

The following exception happens on the Ignite node at the same time: 
{code}
Exception in thread "igfs-#50%null%" java.lang.NullPointerException
	at org.apache.ignite.internal.processors.hadoop.impl.igfs.HadoopIgfsSecondaryFileSystemPositionedReadable.read(HadoopIgfsSecondaryFileSystemPositionedReadable.java:104)
	at org.apache.ignite.internal.processors.igfs.IgfsLazySecondaryFileSystemPositionedReadable.read(IgfsLazySecondaryFileSystemPositionedReadable.java:64)
	at org.apache.ignite.internal.processors.igfs.IgfsDataManager.secondaryDataBlock(IgfsDataManager.java:419)
	at org.apache.ignite.internal.processors.igfs.IgfsDataManager$4.applyx(IgfsDataManager.java:357)
	at org.apache.ignite.internal.processors.igfs.IgfsDataManager$4.applyx(IgfsDataManager.java:346)
	at org.apache.ignite.internal.util.lang.IgniteClosureX.apply(IgniteClosureX.java:38)
	at org.apache.ignite.internal.util.future.GridFutureChainListener.applyCallback(GridFutureChainListener.java:78)
	at org.apache.ignite.internal.util.future.GridFutureChainListener.access$000(GridFutureChainListener.java:30)
	at org.apache.ignite.internal.util.future.GridFutureChainListener$1.run(GridFutureChainListener.java:65)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)
{code}

The problem is that class `org.apache.ignite.internal.processors.hadoop.impl.igfs.HadoopIgfsSecondaryFileSystemPositionedReadable`
was designed fro single-threaded access, but in fact was accessed by multiple threads. That
lead to unexpected situation, when org.apache.ignite.internal.processors.hadoop.impl.igfs.HadoopIgfsSecondaryFileSystemPositionedReadable#in
returned null , that caused a bunch of further errors. 
Fixed by making HadoopIgfsSecondaryFileSystemPositionedReadable thread safe (underlying secondary
file system input stream has its own mechanisms to preserve consistency upon multithreaded
access.)

> NPE in reading data from IGFS
> -----------------------------
>
>                 Key: IGNITE-4862
>                 URL: https://issues.apache.org/jira/browse/IGNITE-4862
>             Project: Ignite
>          Issue Type: Bug
>          Components: hadoop
>    Affects Versions: 1.9
>            Reporter: Dmitry Karachentsev
>            Assignee: Ivan Veselovsky
>            Priority: Minor
>             Fix For: 2.0
>
>
> {noformat}
> D:\app\CodexRT.CodexRT_20170314-1>hadoop\bin\hadoop fs -copyToLocal igfs:///cacheLink/test3.orc
D:\test3.orc
> -copyToLocal: Fatal internal error
> java.lang.NullPointerException
>         at org.apache.ignite.internal.processors.hadoop.impl.igfs.HadoopIgfsInputStream$FetchBufferPart.flatten(HadoopIgfsInputStream.java:458)
>         at org.apache.ignite.internal.processors.hadoop.impl.igfs.HadoopIgfsInputStream$DoubleFetchBuffer.flatten(HadoopIgfsInputStream.java:511)
>         at org.apache.ignite.internal.processors.hadoop.impl.igfs.HadoopIgfsInputStream.read(HadoopIgfsInputStream.java:177)
>         at java.io.DataInputStream.read(DataInputStream.java:100)
>         at org.apache.hadoop.io.IOUtils.copyBytes(IOUtils.java:91)
>         at org.apache.hadoop.io.IOUtils.copyBytes(IOUtils.java:59)
>         at org.apache.hadoop.io.IOUtils.copyBytes(IOUtils.java:119)
>         at org.apache.hadoop.fs.shell.CommandWithDestination$TargetFileSystem.writeStreamToFile(CommandWithDestination.java:466)
>         at org.apache.hadoop.fs.shell.CommandWithDestination.copyStreamToTarget(CommandWithDestination.java:391)
>         at org.apache.hadoop.fs.shell.CommandWithDestination.copyFileToTarget(CommandWithDestination.java:328)
>         at org.apache.hadoop.fs.shell.CommandWithDestination.processPath(CommandWithDestination.java:263)
>         at org.apache.hadoop.fs.shell.CommandWithDestination.processPath(CommandWithDestination.java:248)
>         at org.apache.hadoop.fs.shell.Command.processPaths(Command.java:317)
>         at org.apache.hadoop.fs.shell.Command.processPathArgument(Command.java:289)
>         at org.apache.hadoop.fs.shell.CommandWithDestination.processPathArgument(CommandWithDestination.java:243)
>         at org.apache.hadoop.fs.shell.Command.processArgument(Command.java:271)
>         at org.apache.hadoop.fs.shell.Command.processArguments(Command.java:255)
>         at org.apache.hadoop.fs.shell.CommandWithDestination.processArguments(CommandWithDestination.java:220)
>         at org.apache.hadoop.fs.shell.Command.processRawArguments(Command.java:201)
>         at org.apache.hadoop.fs.shell.Command.run(Command.java:165)
>         at org.apache.hadoop.fs.FsShell.run(FsShell.java:287)
>         at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
>         at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:84)
>         at org.apache.hadoop.fs.FsShell.main(FsShell.java:340)
> {noformat}
> Details in discussion: [http://apache-ignite-users.70518.x6.nabble.com/NullPointerException-when-using-IGFS-td11328.html]



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