apache/hadoop · error · IOException

Cannot seek in {codecName} compressed stream

Error message

Cannot seek in {codecName} compressed stream

What it means

Error "Cannot seek in {codecName} compressed stream" thrown in apache/hadoop.

Source

Thrown at hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/LineRecordReader.java:138

        MRJobConfig.INPUT_FILE_OPTION_PREFIX,
        MRJobConfig.INPUT_FILE_MANDATORY_PREFIX);
    fileIn = FutureIO.awaitFuture(builder.build());
    if (isCompressedInput()) {
      decompressor = CodecPool.getDecompressor(codec);
      if (codec instanceof SplittableCompressionCodec) {
        final SplitCompressionInputStream cIn =
          ((SplittableCompressionCodec)codec).createInputStream(
            fileIn, decompressor, start, end,
            SplittableCompressionCodec.READ_MODE.BYBLOCK);
        in = new CompressedSplitLineReader(cIn, job, recordDelimiter);
        start = cIn.getAdjustedStart();
        end = cIn.getAdjustedEnd();
        filePosition = cIn; // take pos from compressed stream
      } else {
        if (start != 0) {
          // So we have a split that is part of a file stored using
          // a Compression codec that cannot be split.
          throw new IOException("Cannot seek in " +
              codec.getClass().getSimpleName() + " compressed stream");
        }

        in = new SplitLineReader(codec.createInputStream(fileIn,
            decompressor), job, recordDelimiter);
        filePosition = fileIn;
      }
    } else {
      fileIn.seek(start);
      in = new UncompressedSplitLineReader(
          fileIn, job, recordDelimiter, split.getLength());
      filePosition = fileIn;
    }
    // If this is not the first split, we always throw away first record
    // because we always (except the last split) read one extra line in
    // next() method.
    if (start != 0) {
      try {

View on GitHub (pinned to 2add963021)

Solutions

1. Seeking is unsupported in this compressed stream; use a splittable codec such as bzip2, or disable compression for inputs that need random access.

When it happens

Trigger: Thrown at hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/LineRecordReader.java:138 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/e04ec08584fba90c. Report an issue: GitHub.