apache/hadoop · error · IOException

SAX error: {}

Error message

SAX error: {}

What it means

XmlEditsVisitor's constructor emits startDocument() and the opening <EDITS> element through the transformer handler; this IOException wraps a SAXException from those first callbacks. It means the serialization pipeline failed at the very start of output — usually an unusable output stream (the StreamResult target) rather than bad edit-log data.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/XmlEditsVisitor.java:80

    this.out = out;
    try {
      factory = org.apache.hadoop.util.XMLUtils.newSecureSAXTransformerFactory();
      TransformerHandler handler = factory.newTransformerHandler();
      handler.getTransformer().setOutputProperty(OutputKeys.METHOD, "xml");
      handler.getTransformer().setOutputProperty(OutputKeys.ENCODING, "UTF-8");
      handler.getTransformer().setOutputProperty(OutputKeys.INDENT, "yes");
      handler.getTransformer().setOutputProperty(XML_INDENTATION_PROP,
              XML_INDENTATION_NUM);
      handler.getTransformer().setOutputProperty(OutputKeys.STANDALONE, "yes");
      handler.setResult(new StreamResult(out));
      contentHandler = handler;
      
      contentHandler.startDocument();
      contentHandler.startElement("", "", "EDITS", new AttributesImpl());
    } catch (TransformerConfigurationException e) {
      throw new IOException("SAXTransformer error: " + e.getMessage());
    } catch (SAXException e) {
      throw new IOException("SAX error: " + e.getMessage());
    }
  }

  /**
   * Start visitor (initialization)
   */
  @Override
  public void start(int version) throws IOException {
    try {
      contentHandler.startElement("", "", "EDITS_VERSION", new AttributesImpl());
      StringBuilder bld = new StringBuilder();
      bld.append(version);
      addString(bld.toString());
      contentHandler.endElement("", "", "EDITS_VERSION");
    }
    catch (SAXException e) {
      throw new IOException("SAX error: " + e.getMessage());
    }

View on GitHub (pinned to 2add963021)

Solutions

1. Verify the OutputStream is open and writable before constructing the visitor (write and reset a test byte).
2. Open the output file and construct the visitor right before use, not long-lived across failures.
3. Build a fresh XmlEditsVisitor per output file; never reuse instances across runs.
4. If it persists on a valid stream, investigate the JAXP environment (see the SAXTransformer error).

private static OutputStream openWritable(File f) throws IOException {
  OutputStream out = new FileOutputStream(f);
  out.write(' ');   // probe write
  out.flush();
  new RandomAccessFile(f, "rw").setLength(0);  // reset probe
  return out;
}

try {
  visitor = new XmlEditsVisitor(out);
} catch (IOException e) {
  // constructor failed writing <EDITS>; check stream/disk before retrying with a fresh one
  out.close();
  throw e;
}

When it happens

Trigger: new XmlEditsVisitor(out) where the OutputStream passed as StreamResult is already closed, null-wrapped, or fails on first write; a transformer handler left in a bad state from a prior failure.

Common situations: Passing a stream obtained from an already-closed FileOutputStream; reusing a visitor or output target after an earlier error; wrapper streams closed prematurely by application code.

Related errors

• expected <EDITS/>
• can't understand DelegationTokenIdentifier KIND {kind}
• {e}
• Invalid value for FsAction
• expecting </EDITS>

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/a0d7cc9b9672e802. Report an issue: GitHub.