坚果作业失败，退出值为255失败

如何解决坚果作业失败，退出值为255失败

当我为100万个URL运行nutch作业时，nutch作业失败 与

20/10/14 12:40:34 ERROR fetcher.Fetcher: Fetcher: java.lang.RuntimeException: Fetcher job did not succeed,job status:Failed,reason: Task Failed task_1601725692999_0307_m_000004
Job Failed as tasks Failed. FailedMaps:1 FailedReduces:0

    at org.apache.nutch.fetcher.Fetcher.fetch(Fetcher.java:500)
    at org.apache.nutch.fetcher.Fetcher.run(Fetcher.java:541)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
    at org.apache.nutch.fetcher.Fetcher.main(Fetcher.java:514)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.hadoop.util.RunJar.run(RunJar.java:244)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:158)

Error running:
  /home/hadoop/apache-nutch-1.17/runtime/deploy/bin/nutch fetch -Dmapreduce.map.memory.mb=2048 -Dmapreduce.map.java.opts=-Xmx2048m -Dmapreduce.reduce.memory.mb=2048 -Dmapreduce.reduce.java.opts=-Xmx2048m -Dmapreduce.job.reduces=12 -Dmapreduce.reduce.speculative=false -Dmapreduce.map.speculative=false -Dmapreduce.map.output.compress=true -D fetcher.timelimit.mins=300 s3a://pt-test-1/nutch/1million-crawls//segments/20201014115727 -threads 400
Failed with exit value 255.

解决方法

失败的原因显示在task_1601725692999_0307_m_000004的日志中。它也显示在Hadoop UI的任务表中。

最可能的原因： -Dmapreduce.map.memory.mb=2048 -Dmapreduce.map.java.opts=-Xmx2048m mapreduce.map.memory.mb必须大于Java堆内存。我建议将512 MB添加到mapreduce.map.memory.mb。