MyCATApache/Mycat-Server · error · IllegalStateException

Writer already closed. Cannot be reopened.

Error message

Writer already closed. Cannot be reopened.

What it means

DiskRowWriter.open() re-acquires the file output stream, channel, and buffered stream. Once the writer has been closed, hasBeenClosed is set and any further open() call throws IllegalStateException 'Writer already closed. Cannot be reopened.' Closed writers are intentionally not reusable.

Solutions

1. Create a new DiskRowWriter for the file instead of reopening the closed one
2. Track writer state in the caller and stop issuing writes after close
3. If retry semantics are needed, wrap write in a factory method that builds a fresh writer per attempt

Example fix

// before
writer.close();
writer.write(row); // IllegalStateException
// after
writer.close();
DiskRowWriter writer2 = new DiskRowWriter(file, bufferSize);
writer2.open().write(row);

if (!writer.isClosed()) { writer.write(row); } else { writer = writerFactory.create(file); writer.write(row); }

boolean isWritable(DiskRowWriter w) { return w != null && !w.hasBeenClosed(); }

try { writer.write(row); } catch (IllegalStateException e) { writer = new DiskRowWriter(file, bufferSize); writer.write(row); }

When it happens

Trigger: Calling write() (which internally calls open()) after close() was invoked on the same DiskRowWriter; reusing a writer object across lifecycle phases after finishing a batch.

Common situations: Retrying a failed append with the same writer after close; object pooling code that returns closed writers to a pool; a consumer callback firing after the writer finished a spill file.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

• error while calling spill() on
• error while calling spill() on
• Have already allocated a maximum of
• Failed to create local dir in $newDir.
• Failed to delete:

AI-assisted analysis of MyCATApache/Mycat-Server@65f8d8beb7 (2026-09-11). Data as JSON: /api/errors/a6bad673b4c640bb. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/io/mycat/memory/unsafe/storage/DiskRowWriter.java:105

          OutputStream compressStream ,
          boolean syncWrites,
          ConnectionId blockId) throws IOException {

    this.file = file;
    this.serializerInstance = serializerInstance;
    this.bufferSize = bufferSize;
    this.compressStream = compressStream;
    this.syncWrites = syncWrites;
    this.blockId = blockId;
    initialPosition = file.length();
    reportedPosition = initialPosition;
  }


  public DiskRowWriter open() throws FileNotFoundException {

    if (hasBeenClosed) {
      throw new IllegalStateException("Writer already closed. Cannot be reopened.");
    }

    fos = new FileOutputStream(file,true);
    ts = new TimeTrackingOutputStream(/**writeMetrics,*/ fos);
    channel = fos.getChannel();
    bs = new BufferedOutputStream(ts,bufferSize);
    objOut = serializerInstance.serializeStream(bs);
    initialized = true;

    return this;

  }


  @Override
  public void close() {
    if (initialized) {
      try {

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