{"record":{"id":"c2b980500dc49900","repo":"apache/hadoop","slug":"classname-does-not-support-setting-the-readahea-c2b980","errorCode":null,"errorMessage":"${className} does not support setting the readahead caching strategy.","messagePattern":"(.+?) does not support setting the readahead caching strategy\\.","errorType":"exception","errorClass":"UnsupportedOperationException","httpStatus":null,"severity":"error","filePath":"hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FSDataInputStream.java","lineNumber":181,"sourceCode":"\n  @Override\n  public FileDescriptor getFileDescriptor() throws IOException {\n    if (in instanceof HasFileDescriptor) {\n      return ((HasFileDescriptor) in).getFileDescriptor();\n    } else if (in instanceof FileInputStream) {\n      return ((FileInputStream) in).getFD();\n    } else {\n      return null;\n    }\n  }\n\n  @Override\n  public void setReadahead(Long readahead)\n      throws IOException, UnsupportedOperationException {\n    try {\n      ((CanSetReadahead)in).setReadahead(readahead);\n    } catch (ClassCastException e) {\n      throw new UnsupportedOperationException(in.getClass().getCanonicalName() +\n          \" does not support setting the readahead caching strategy.\");\n    }\n  }\n\n  @Override\n  public void setDropBehind(Boolean dropBehind)\n      throws IOException, UnsupportedOperationException {\n    try {\n      ((CanSetDropBehind)in).setDropBehind(dropBehind);\n    } catch (ClassCastException e) {\n      throw new UnsupportedOperationException(\"this stream does not \" +\n          \"support setting the drop-behind caching setting.\");\n    }\n  }\n\n  @Override\n  public ByteBuffer read(ByteBufferPool bufferPool, int maxLength,\n      EnumSet<ReadOption> opts) ","sourceCodeStart":163,"sourceCodeEnd":199,"githubUrl":"https://github.com/apache/hadoop/blob/2add9630210752f88ceb1bb74eb65e37bf41da8e/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FSDataInputStream.java#L163-L199","documentation":"Error \"${className} does not support setting the readahead caching strategy.\" thrown in apache/hadoop.","triggerScenarios":"Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FSDataInputStream.java:181 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Only call setReadaheadStrategy on streams whose wrapped input supports it (e.g. HDFS streams).","Guard the call with an instanceof/capability check and skip when unsupported."],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"2add9630210752f88ceb1bb74eb65e37bf41da8e","analyzedAt":"2026-08-22T19:55:07.957Z","schemaVersion":2},"datasetVersion":"2026-08-23T01:17:44.959Z"}