[AVRO-3482] DataFileReader should reuse MAGIC data read from inputstream

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.11.1, 1.12.0
• Labels: performance pull-request-available
• Assignee: Rajesh Balamohan
• Reporter: Rajesh Balamohan
• Created: 08/Apr/22 06:49
• Updated: 04/May/22 08:00
• Resolved: 27/Apr/22 22:35

Description

https://github.com/apache/avro/blob/master/lang/java/avro/src/main/java/org/apache/avro/file/DataFileReader.java#L60-L72

 

byte[] magic = new byte[MAGIC.length];
    in.seek(0);
    int offset = 0;
    int length = magic.length;
    while (length > 0) {
      int bytesRead = in.read(magic, offset, length);
      if (bytesRead < 0)
        throw new EOFException("Unexpected EOF with " + length + " bytes remaining to read");

      length -= bytesRead;
      offset += bytesRead;
    }
    in.seek(0); <--- This will force the inputstream to switch to "random" io policy in next read in cloud connectors!

    if (Arrays.equals(MAGIC, magic)) // current format
      return new DataFileReader<>(in, reader);
    if (Arrays.equals(DataFileReader12.MAGIC, magic)) // 1.2 format
      return new DataFileReader12<>(in, reader);

 

 

With cloud stores, this can turn out to be expensive as the stream has to be closed and reopened in cloud connectors (e.g s3).

It will be helpful to reuse the MAGIC bytes read from inputstream and pass it on to DataFileReader / DataFileReader12. This will ensure that, file can be read in sequential manner in cloud stores and help in reducing IO calls.

Issue Links

• links to: GitHub Pull Request #1639