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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 2:45 PM:
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The property {{prefetchBlocks}} must be set to non-zero value to reproduce the
problem ({{perNodeParallelBatchCount}} should be > 0, but it is 16 by default):
{code}
<bean
class="org.apache.ignite.configuration.FileSystemConfiguration">
.....
<property name="prefetchBlocks" value="32"/>
{code}
After that the problem was reproducible just after node start with an attempt
to read a 44Mb file via IGFS (with {{./hadoop-ig fs -copyToLocal
igfs://localhost:10500/tmp/myfile /tmp/ }}) that exists on HDFS (secondary Fs),
but is yet missing in the IGFS caches.
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 property {{prefetchBlocks}} must be set to non-zero value to reproduce the
problem ({{perNodeParallelBatchCount}} should be > 0, but it is 16 by default):
{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.)
> 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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