Error sink worker thread is still alive after close…

Error message

Error sink worker thread is still alive after close timeout. jobId={}, pluginName={}, threadName={}. Will release the error sink classloader anyway to reduce classloader leak risk.

What it means

DefaultErrorSinkWriter.close() waits DEFAULT_CLOSE_TIMEOUT_MILLIS for the error-sink worker thread to finish. If the thread is still alive after the timeout, this warning is logged and the error-sink classloader is released anyway to avoid leaking it. It indicates the error sink could not finish draining within the close timeout, so data may have been dropped.

Solutions

Check the error sink (pluginName in the log) for slowness or blocked connections and increase its write throughput or batch size.
Ensure the job is cancelled gracefully so the drain loop can finish before close.
Check for stuck network/DB connections from the sink and tune its timeout options.
If leaks persist, verify plugin classloader cleanup and report/inspect DefaultErrorSinkWriter timeout behavior for your SeaTunnel version.

Example fix

// before: no graceful drain, worker blocked on slow sink
sinkWriter.write(record); // blocking JDBC call with no timeout
// after: bound the write so close() can finish in time
statement.setQueryTimeout(10);
sinkWriter.write(record);

Defensive patterns

Strategy: fallback

Try / catch

// close() already swallows; monitor logs
try {
    errorSinkWriter.close();
} catch (Throwable t) {
    log.error("error sink close failed after timeout", t);
}

Prevention

Keep the error sink fast (timeouts on JDBC statements, batch tuning).
Cancel/stop jobs gracefully rather than hard-kill so the drain loop drains.
Watch logs for this warning as an indicator of slow error sinks.
Size the close timeout for your sink's worst-case latency.

When it happens

Trigger: close() is called while the drain loop still has queued error records and the sink writer (e.g. a slow JDBC/error sink) does not terminate within the close timeout, leaving currentWorkerThread alive.

Common situations: Error sink writing to a slow/unresponsive database or network sink during job shutdown; a sink writer blocked in I/O (e.g. MySQL connection stuck); excessive queued error rows at cancel/stop time.

Understand the failure class

Timeouts: ETIMEDOUT, deadlines, and hung requests — what actually expires when a request times out.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/919eb0658e1976f5. Report an issue: GitHub.

Appendix: source

Thrown at seatunnel-engine/seatunnel-engine-server/src/main/java/org/apache/seatunnel/engine/server/task/error/DefaultErrorSinkWriter.java:271

                throw new RuntimeException(e);
            }
        }
        throwWorkerFailureIfAny();
    }

    @Override
    public void close() throws Exception {
        closed = true;
        Thread currentWorkerThread = workerThread;
        if (currentWorkerThread != null) {
            currentWorkerThread.interrupt();
        }
        waitForWorkerTermination(DEFAULT_CLOSE_TIMEOUT_MILLIS);

        Throwable closeEx = null;
        try {
            if (currentWorkerThread != null && currentWorkerThread.isAlive()) {
                log.warn(
                        "Error sink worker thread is still alive after close timeout. jobId={}, pluginName={}, threadName={}. "
                                + "Will release the error sink classloader anyway to reduce classloader leak risk.",
                        jobId,
                        sinkConfig.getPluginName(),
                        currentWorkerThread.getName());
                closeEx =
                        new RuntimeException(
                                String.format(
                                        "Timed out waiting for error sink worker to close. jobId=%d, pluginName=%s",
                                        jobId, sinkConfig.getPluginName()));
            } else {
                // Worker thread stopped; close remaining resources.
                closeWriterIfPossible();
            }
        } catch (Throwable e) {
            closeEx = e;
            log.warn("Failed to close error sink writer", e);
        } finally {

View on GitHub (pinned to cf67b549a7)