What causes "Failed to close failure-data writer. cause={}" in apache/seatunnel?

Check disk space and mount health on the worker node at job shutdown

Failed to close failure-data writer. cause=

Error message

Failed to close failure-data writer. cause={}

What it means

Logged by BatchBuffer.closeFailureWriter during task close() when closing the BufferedWriter for the failure-data file throws an IOException. The reference is nulled in a finally block so no leak persists; the warning only means buffered failure samples may not have been fully flushed to disk at close time.

Solutions

Check disk space and mount health on the worker node at job shutdown
Review the failure-data file for truncated final lines; treat the last sample as possibly incomplete
Ensure the failureDataPath points to reliable local storage rather than a flaky network mount
This is logged as WARN and does not fail the job; re-run data validation if failure samples matter for auditing

Defensive patterns

Strategy: try-catch

Try / catch

// The connector already swallows this; treat it as advisory:
// after close(), optionally verify the failure file is complete
if (!failureFileComplete(failureDataPath)) {
    LOG.warn("failure samples may be truncated due to close error");
}

Prevention

Use reliable local storage (not flaky network mounts) for failureDataPath
Keep adequate disk headroom so close-time flush cannot fail from disk-full
Avoid external cleanup cron jobs that delete files under running jobs
Validate failure-sample contents after jobs that logged this warning

When it happens

Trigger: failureWriter.close() throws IOException during the sink's close lifecycle: disk full while flushing remaining buffered lines, the underlying file was removed/unclosed mount, or the filesystem became unavailable before job shutdown. Called once from close().

Common situations: Disk-full on the worker during shutdown, NFS/network mounts dropped mid-job, or container shutdown racing with the flush of the failure-sample file.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/c8698270faf3a7f6. Report an issue: GitHub.

Appendix: source

Thrown at seatunnel-connectors-v2/connector-hugegraph/src/main/java/org/apache/seatunnel/connectors/seatunnel/hugegraph/buffer/BatchBuffer.java:440

            }
            closed = true;
        }

        LOG.info("Closing BatchBuffer, performing final flush...");
        try {
            flush();
        } finally {
            closeFailureWriter();
        }
        LOG.info("BatchBuffer closed.");
    }

    private void closeFailureWriter() {
        if (failureWriter != null) {
            try {
                failureWriter.close();
            } catch (IOException e) {
                LOG.warn("Failed to close failure-data writer. cause={}", e.getMessage());
            } finally {
                failureWriter = null;
            }
        }
    }
}

View on GitHub (pinned to cf67b549a7)