apache/seatunnel · warning · CassandraConnectorException

CLOSE_CQL_SESSION_FAILED

CLOSE_CQL_SESSION_FAILED

Error message

CLOSE_CQL_SESSION_FAILED

What it means

CassandraSinkWriter.close() flushes then closes the CqlSession; if session.close() throws, the error is wrapped as CLOSE_CQL_SESSION_FAILED. The writer already flushed successfully, so pending data is safe — but the session cleanup failed, typically due to broken connections during shutdown.

Source

Thrown at seatunnel-connectors-v2/connector-cassandra/src/main/java/org/apache/seatunnel/connectors/seatunnel/cassandra/sink/CassandraSinkWriter.java:154

    private String initPrepareCQL() {
        String[] placeholder = new String[cassandraParameters.getFields().size()];
        Arrays.fill(placeholder, "?");
        return String.format(
                "INSERT INTO %s (%s) VALUES (%s)",
                cassandraParameters.getTable(),
                String.join(",", cassandraParameters.getFields()),
                String.join(",", placeholder));
    }

    @Override
    public void close() throws IOException {
        flush();
        try {
            if (this.session != null) {
                this.session.close();
            }
        } catch (Exception e) {
            throw new CassandraConnectorException(
                    CassandraConnectorErrorCode.CLOSE_CQL_SESSION_FAILED, e);
        }
    }
}

View on GitHub (pinned to cf67b549a7)

Solutions

1. Usually safe to ignore for data correctness (flush already succeeded); verify checkpoint completed and data landed in the table.
2. Check Cassandra node logs for disconnect reasons; fix network instability or node restarts during job lifetime.
3. Ensure async writes are fully completed before close — increase flush/await windows if in-flight requests overlap shutdown.
4. Upgrade the Cassandra Java driver if close consistently throws after healthy writes (known channel-close race issues).

Example fix

// before
try {
    if (this.session != null) {
        this.session.close();
    }
} catch (Exception e) {
    throw new CassandraConnectorException(CLOSE_CQL_SESSION_FAILED, e);
}
// after (application-side guard)
try (SinkWriter writer = ...) {
    ...
} catch (CassandraConnectorException e) {
    if (e.getCode() == CLOSE_CQL_SESSION_FAILED) {
        log.warn("Session close failed after flush; data already flushed", e);
    } else {
        throw e;
    }
}

// safe to downgrade: flush already completed before close
try {
    writer.close();
} catch (CassandraConnectorException e) {
    if (CassandraConnectorErrorCode.CLOSE_CQL_SESSION_FAILED.equals(e.getErrorCode())) {
        log.warn("ignoring session close failure after successful flush");
    } else { throw e; }
}

When it happens

Trigger: this.session.close() throws — happens when the driver's channels are already dead (cluster restarted/network partitioned), or when close is racing with in-flight async writes that hold onto the session.

Common situations: Cassandra cluster unavailability at job shutdown; very short-lived tasks where the node disconnected before close; driver force-closing channels with in-flight requests.

Understand the failure class

Background: ECONNREFUSED and "connection refused" / "could not connect to server" errors: what they mean and how to fix them — this error's family across 44 libraries.

Related errors

• COMMON_ERROR_CODE_DEPRECATED_TABLE_SCHEMA_GET_FAILED
• TABLE_SCHEMA_GET_FAILED
• RABBITMQ-03
• Failed to close catalog
• Failed to close Fluss connection for {}

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/2fd40081eb06ae69. Report an issue: GitHub.