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Due to some error at one component, files in HDFS got accumulated and the number is huge i.e 2123516. I want to list all files and want to copy their name in one file but when I run the following command, it gives Java heap space error.

hdfs dfs -ls /tmp/content/

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at java.util.Arrays.copyOf(Arrays.java:3332)
    at java.lang.AbstractStringBuilder.expandCapacity(AbstractStringBuilder.java:137)
    at java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:121)
    at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:421)
    at java.lang.StringBuffer.append(StringBuffer.java:272)
    at java.net.URI.appendSchemeSpecificPart(URI.java:1911)
    at java.net.URI.toString(URI.java:1941)
    at java.net.URI.<init>(URI.java:742)
    at org.apache.hadoop.fs.Path.initialize(Path.java:145)
    at org.apache.hadoop.fs.Path.<init>(Path.java:126)
    at org.apache.hadoop.fs.Path.<init>(Path.java:50)
    at org.apache.hadoop.hdfs.protocol.HdfsFileStatus.getFullPath(HdfsFileStatus.java:215)
    at org.apache.hadoop.hdfs.DistributedFileSystem.makeQualified(DistributedFileSystem.java:252)
    at org.apache.hadoop.hdfs.DistributedFileSystem.listStatus(DistributedFileSystem.java:311)
    at org.apache.hadoop.fs.FileSystem.listStatus(FileSystem.java:842)
    at org.apache.hadoop.fs.FileSystem.listStatus(FileSystem.java:902)
    at org.apache.hadoop.fs.FileSystem.globStatusInternal(FileSystem.java:1032)
    at org.apache.hadoop.fs.FileSystem.globStatus(FileSystem.java:987)
    at org.apache.hadoop.fs.FileSystem.globStatus(FileSystem.java:965)
    at org.apache.hadoop.fs.shell.Command.runAll(Command.java:62)
    at org.apache.hadoop.fs.FsShell.run(FsShell.java:1822)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
    at org.apache.hadoop.fs.FsShell.main(FsShell.java:1895)

Is there any other way to list the files and how much heap space is required to list 2400000 files?

1 Answer 1

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You can try increasing CLI heap size by setting HADOOP_HEAPSIZE env. variable, for example:

$ HADOOP_HEAPSIZE=1000 hdfs dfs -ls /tmp/content

The number is in MB, so just be gentle :)

Bigger question is what you're going to do with over 2M files on the console? Aren't you planning to redirect output somewhere?

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