Hadoop 中的内存不足错误

java hadoop

2022-08-31 16:02:08

我尝试按照此 http://hadoop.apache.org/common/docs/stable/single_node_setup.html 文档安装Hadoop。当我尝试执行此命令时

bin/hadoop jar hadoop-examples-*.jar grep input output 'dfs[a-z.]+'

我收到以下异常

java.lang.OutOfMemoryError: Java heap space

请提出一个解决方案，以便我可以尝试这个例子。下面列出了整个异常。我是Hadoop的新手，我可能做了一些愚蠢的事情。任何建议将不胜感激。

anuj@anuj-VPCEA13EN:~/hadoop$ bin/hadoop jar hadoop-examples-*.jar grep input output 'dfs[a-z.]+'
11/12/11 17:38:22 INFO util.NativeCodeLoader: Loaded the native-hadoop library
11/12/11 17:38:22 INFO mapred.FileInputFormat: Total input paths to process : 7
11/12/11 17:38:22 INFO mapred.JobClient: Running job: job_local_0001
11/12/11 17:38:22 INFO util.ProcessTree: setsid exited with exit code 0
11/12/11 17:38:22 INFO mapred.Task:  Using ResourceCalculatorPlugin : org.apache.hadoop.util.LinuxResourceCalculatorPlugin@e49dcd
11/12/11 17:38:22 INFO mapred.MapTask: numReduceTasks: 1
11/12/11 17:38:22 INFO mapred.MapTask: io.sort.mb = 100
11/12/11 17:38:22 WARN mapred.LocalJobRunner: job_local_0001
java.lang.OutOfMemoryError: Java heap space
    at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.<init>(MapTask.java:949)
    at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:428)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:372)
    at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:212)
11/12/11 17:38:23 INFO mapred.JobClient:  map 0% reduce 0%
11/12/11 17:38:23 INFO mapred.JobClient: Job complete: job_local_0001
11/12/11 17:38:23 INFO mapred.JobClient: Counters: 0
11/12/11 17:38:23 INFO mapred.JobClient: Job Failed: NA
java.io.IOException: Job failed!
    at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1257)
    at org.apache.hadoop.examples.Grep.run(Grep.java:69)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
    at org.apache.hadoop.examples.Grep.main(Grep.java:93)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:68)
    at org.apache.hadoop.util.ProgramDriver.driver(ProgramDriver.java:139)
    at org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:64)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:156)

答案 1

对于任何使用 RPM 或 DEB 软件包的人来说，文档和常见建议都具有误导性。这些软件包将 hadoop 配置文件安装到 /etc/hadoop 中。这些设置将优先于其他设置。

/etc/hadoop/hadoop-env.sh 为 Hadoop 设置了最大的 java 堆内存，默认情况下它是：

   export HADOOP_CLIENT_OPTS="-Xmx128m $HADOOP_CLIENT_OPTS"

此 Xmx 设置太低，只需将其更改为此设置并重新运行即可

   export HADOOP_CLIENT_OPTS="-Xmx2048m $HADOOP_CLIENT_OPTS"

答案 2

您可以通过编辑 conf/mapred-site.xml 文件并添加属性来分配更多内存：

  <property>
    <name>mapred.child.java.opts</name>
    <value>-Xmx1024m</value>
  </property>

这将启动具有更多堆空间的 hadoop JVM。