apache/seatunnel · error · IllegalArgumentException

input.multiline.flush-idle-timeout-ms must be > 0 when multi

Error message

input.multiline.flush-idle-timeout-ms must be > 0 when multiline is enabled, otherwise the buffer may never flush (input id=${id}).

What it means

When multiline aggregation is enabled, a flush idle timeout of 0 or less means an unterminated multiline buffer may never be flushed. FileCollectConfig enforces a strictly positive timeout in that case and throws this IllegalArgumentException.

Source

Thrown at seatunnel-edge-agent/seatunnel-edge-agent-connector/src/main/java/org/apache/seatunnel/edge/agent/connector/config/FileCollectConfig.java:93

                config.getOptional(FileCollectOptions.MULTILINE_PATTERN).orElse(null);
        this.multilineMatch = config.get(FileCollectOptions.MULTILINE_MATCH);
        validateMultilineMatch(this.multilineMatch);
        this.multilineNegate = config.get(FileCollectOptions.MULTILINE_NEGATE);
        this.multilineMaxLines = config.get(FileCollectOptions.MULTILINE_MAX_LINES);
        if (this.multilineMaxLines < 1) {
            throw new IllegalArgumentException(
                    "input.multiline.max-lines must be >= 1 when set (input id=" + this.id + ").");
        }
        this.multilineFlushIdleTimeoutMs =
                config.get(FileCollectOptions.MULTILINE_FLUSH_IDLE_TIMEOUT_MS);
        if (this.multilineFlushIdleTimeoutMs < 0L) {
            throw new IllegalArgumentException(
                    "input.multiline.flush-idle-timeout-ms must not be negative (input id="
                            + this.id
                            + ").");
        }
        if (isMultilineEnabled() && this.multilineFlushIdleTimeoutMs <= 0L) {
            throw new IllegalArgumentException(
                    "input.multiline.flush-idle-timeout-ms must be > 0 when multiline is enabled,"
                            + " otherwise the buffer may never flush (input id="
                            + this.id
                            + ").");
        }
        this.outputType = config.get(FileCollectOptions.OUTPUT_FORMAT_TYPE);
        validateOutputType(this.outputType);
        this.onError = config.get(FileCollectOptions.ON_ERROR);
        validateOnError(this.onError);
        this.globScanIntervalMs = config.get(FileCollectOptions.GLOB_SCAN_INTERVAL_MS);
        if (this.globScanIntervalMs < 1L) {
            throw new IllegalArgumentException(
                    "input.glob-scan-interval-ms must be >= 1 when set (input id="
                            + this.id
                            + ").");
        }
        this.closeInactiveMs = config.get(FileCollectOptions.CLOSE_INACTIVE_MS);
        if (this.closeInactiveMs < 0L) {

View on GitHub (pinned to cf67b549a7)

Solutions

1. Set input.multiline.flush-idle-timeout-ms to a positive value, e.g. 5000-60000
2. Disable multiline aggregation if line-by-line parsing is intended
3. Keep the timeout >0 whenever multiline.pattern/multiline.match are configured

Example fix

# before
multiline.pattern = "^[0-9]{4}-"
multiline.match = "after"
multiline.flush-idle-timeout-ms = 0
# after
multiline.pattern = "^[0-9]{4}-"
multiline.match = "after"
multiline.flush-idle-timeout-ms = 10000

boolean multilineEnabled = cfg.contains(FileCollectOptions.MULTILINE_PATTERN) || cfg.contains(FileCollectOptions.MULTILINE_MATCH);
Long t = cfg.getOptional(FileCollectOptions.MULTILINE_FLUSH_IDLE_TIMEOUT_MS).orElse(null);
if (multilineEnabled && t != null && t <= 0L) { throw new IllegalArgumentException("flush-idle-timeout-ms must be > 0 when multiline enabled"); }

try { FileCollectConfig.from(config); } catch (IllegalArgumentException e) { log.error("Multiline config invalid: {}", e.getMessage()); }

When it happens

Trigger: Enabling multiline (multiline.pattern or multiline.match set) while input.multiline.flush-idle-timeout-ms is 0 or omitted-but-resolves-to-0.

Common situations: Users set the timeout to 0 thinking it means 'flush immediately', not realizing it means 'never flush' when multiline is active.

Understand the failure class

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

Related errors

• input.multiline.match must be "after" or "before".
• Schema config can not be empty
• Unknown format type:
• Option '${option}' cannot be blank
• Option '${valuesAndOptions[index + 1]}' is not valid for the

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/169dd1a2eeb2a9a6. Report an issue: GitHub.