From 5446098653e394de42d20a70972529d8aca62c93 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Iv=C3=A1n=20Ovejero?= <ivov.src@gmail.com>
Date: Wed, 4 Feb 2026 11:39:18 +0100
Subject: [PATCH] perf(core): Make event loop block detection configurable
 (#25291)

---
 .../@n8n/config/src/configs/sentry.config.ts   | 10 ++++++++++
 packages/@n8n/config/test/config.test.ts       |  1 +
 packages/cli/src/commands/base-command.ts      | 11 +++++++++--
 packages/core/src/errors/error-reporter.ts     | 18 +++++++++++++-----
 4 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/packages/@n8n/config/src/configs/sentry.config.ts b/packages/@n8n/config/src/configs/sentry.config.ts
index c9169df48ba..12cbb1385a8 100644
--- a/packages/@n8n/config/src/configs/sentry.config.ts
+++ b/packages/@n8n/config/src/configs/sentry.config.ts
@@ -35,6 +35,16 @@ export class SentryConfig {
 	@Env('N8N_SENTRY_PROFILES_SAMPLE_RATE', sampleRateSchema)
 	profilesSampleRate: number = 0;
 
+	/**
+	 * Threshold in milliseconds for event loop block detection.
+	 * When the event loop is blocked for longer than this threshold,
+	 * Sentry will report it.
+	 *
+	 * @default 500
+	 */
+	@Env('N8N_SENTRY_EVENT_LOOP_BLOCK_THRESHOLD', z.number({ coerce: true }).int().positive())
+	eventLoopBlockThreshold: number = 500;
+
 	/**
 	 * Environment of the n8n instance.
 	 *
diff --git a/packages/@n8n/config/test/config.test.ts b/packages/@n8n/config/test/config.test.ts
index 9875fb6516c..45ca584ad77 100644
--- a/packages/@n8n/config/test/config.test.ts
+++ b/packages/@n8n/config/test/config.test.ts
@@ -285,6 +285,7 @@ describe('GlobalConfig', () => {
 			deploymentName: '',
 			profilesSampleRate: 0,
 			tracesSampleRate: 0,
+			eventLoopBlockThreshold: 500,
 		},
 		logging: {
 			level: 'info',
diff --git a/packages/cli/src/commands/base-command.ts b/packages/cli/src/commands/base-command.ts
index 2f22d5deb0f..7cac138a274 100644
--- a/packages/cli/src/commands/base-command.ts
+++ b/packages/cli/src/commands/base-command.ts
@@ -84,8 +84,14 @@ export abstract class BaseCommand<F = never> {
 		this.dbConnection = Container.get(DbConnection);
 		this.errorReporter = Container.get(ErrorReporter);
 
-		const { backendDsn, environment, deploymentName, profilesSampleRate, tracesSampleRate } =
-			this.globalConfig.sentry;
+		const {
+			backendDsn,
+			environment,
+			deploymentName,
+			profilesSampleRate,
+			tracesSampleRate,
+			eventLoopBlockThreshold,
+		} = this.globalConfig.sentry;
 		await this.errorReporter.init({
 			serverType: this.instanceSettings.instanceType,
 			dsn: backendDsn,
@@ -94,6 +100,7 @@ export abstract class BaseCommand<F = never> {
 			serverName: deploymentName,
 			releaseDate: N8N_RELEASE_DATE,
 			withEventLoopBlockDetection: true,
+			eventLoopBlockThreshold,
 			tracesSampleRate,
 			profilesSampleRate,
 			eligibleIntegrations: {
diff --git a/packages/core/src/errors/error-reporter.ts b/packages/core/src/errors/error-reporter.ts
index bf1305fcbd8..069848555dc 100644
--- a/packages/core/src/errors/error-reporter.ts
+++ b/packages/core/src/errors/error-reporter.ts
@@ -23,6 +23,9 @@ type ErrorReporterInitOptions = {
 	/** Whether to enable event loop block detection, if Sentry is enabled. */
 	withEventLoopBlockDetection: boolean;
 
+	/** Threshold in ms for event loop block detection. Only used if `withEventLoopBlockDetection` is true. */
+	eventLoopBlockThreshold?: number;
+
 	/** Sample rate for Sentry traces (0.0 to 1.0). 0 means disabled */
 	tracesSampleRate: number;
 
@@ -107,6 +110,7 @@ export class ErrorReporter {
 		serverName,
 		releaseDate,
 		withEventLoopBlockDetection,
+		eventLoopBlockThreshold,
 		profilesSampleRate,
 		tracesSampleRate,
 		eligibleIntegrations = {},
@@ -174,10 +178,13 @@ export class ErrorReporter {
 		const eventLoopBlockIntegration = withEventLoopBlockDetection
 			? // The EventLoopBlockIntegration doesn't automatically include the
 				// same tags, so we set them explicitly.
-				await this.getEventLoopBlockIntegration({
-					server_name: serverName,
-					server_type: serverType,
-				})
+				await this.getEventLoopBlockIntegration(
+					{
+						server_name: serverName,
+						server_type: serverType,
+					},
+					eventLoopBlockThreshold,
+				)
 			: [];
 
 		const profilingIntegration = isProfilingEnabled ? await this.getProfilingIntegration() : [];
@@ -312,11 +319,12 @@ export class ErrorReporter {
 		if (tags) event.tags = { ...event.tags, ...tags };
 	}
 
-	private async getEventLoopBlockIntegration(tags: Record<string, string>) {
+	private async getEventLoopBlockIntegration(tags: Record<string, string>, threshold?: number) {
 		try {
 			const { eventLoopBlockIntegration } = await import('@sentry/node-native');
 			return [
 				eventLoopBlockIntegration({
+					...(threshold ? { threshold } : {}),
 					staticTags: tags,
 				}),
 			];