Improve schedule engine performance

Author: ericallam

apps/webapp/app/env.server.ts

@@ -618,6 +618,9 @@ const EnvironmentSchema = z.object({
   LEGACY_RUN_ENGINE_WORKER_IMMEDIATE_POLL_INTERVAL: z.coerce.number().int().default(50),
   LEGACY_RUN_ENGINE_WORKER_CONCURRENCY_LIMIT: z.coerce.number().int().default(100),
   LEGACY_RUN_ENGINE_WORKER_SHUTDOWN_TIMEOUT_MS: z.coerce.number().int().default(60_000),
+  LEGACY_RUN_ENGINE_WORKER_LOG_LEVEL: z
+    .enum(["log", "error", "warn", "info", "debug"])
+    .default("info"),
 
   LEGACY_RUN_ENGINE_WORKER_REDIS_HOST: z
     .string()
@@ -661,6 +664,7 @@ const EnvironmentSchema = z.object({
   COMMON_WORKER_IMMEDIATE_POLL_INTERVAL: z.coerce.number().int().default(50),
   COMMON_WORKER_CONCURRENCY_LIMIT: z.coerce.number().int().default(100),
   COMMON_WORKER_SHUTDOWN_TIMEOUT_MS: z.coerce.number().int().default(60_000),
+  COMMON_WORKER_LOG_LEVEL: z.enum(["log", "error", "warn", "info", "debug"]).default("info"),
 
   COMMON_WORKER_REDIS_HOST: z
     .string()
@@ -699,6 +703,7 @@ const EnvironmentSchema = z.object({
   ALERTS_WORKER_IMMEDIATE_POLL_INTERVAL: z.coerce.number().int().default(100),
   ALERTS_WORKER_CONCURRENCY_LIMIT: z.coerce.number().int().default(100),
   ALERTS_WORKER_SHUTDOWN_TIMEOUT_MS: z.coerce.number().int().default(60_000),
+  ALERTS_WORKER_LOG_LEVEL: z.enum(["log", "error", "warn", "info", "debug"]).default("info"),
 
   ALERTS_WORKER_REDIS_HOST: z
     .string()
@@ -732,8 +737,8 @@ const EnvironmentSchema = z.object({
 
   SCHEDULE_ENGINE_LOG_LEVEL: z.enum(["log", "error", "warn", "info", "debug"]).default("info"),
   SCHEDULE_WORKER_ENABLED: z.string().default(process.env.WORKER_ENABLED ?? "true"),
-  SCHEDULE_WORKER_CONCURRENCY_WORKERS: z.coerce.number().int().default(1),
-  SCHEDULE_WORKER_CONCURRENCY_TASKS_PER_WORKER: z.coerce.number().int().default(1),
+  SCHEDULE_WORKER_CONCURRENCY_WORKERS: z.coerce.number().int().default(2),
+  SCHEDULE_WORKER_CONCURRENCY_TASKS_PER_WORKER: z.coerce.number().int().default(10),
   SCHEDULE_WORKER_POLL_INTERVAL: z.coerce.number().int().default(1000),
   SCHEDULE_WORKER_IMMEDIATE_POLL_INTERVAL: z.coerce.number().int().default(50),
   SCHEDULE_WORKER_CONCURRENCY_LIMIT: z.coerce.number().int().default(50),

apps/webapp/app/v3/alertsWorker.server.ts

@@ -61,7 +61,7 @@ function initializeWorker() {
     pollIntervalMs: env.ALERTS_WORKER_POLL_INTERVAL,
     immediatePollIntervalMs: env.ALERTS_WORKER_IMMEDIATE_POLL_INTERVAL,
     shutdownTimeoutMs: env.ALERTS_WORKER_SHUTDOWN_TIMEOUT_MS,
-    logger: new Logger("AlertsWorker", "debug"),
+    logger: new Logger("AlertsWorker", env.ALERTS_WORKER_LOG_LEVEL),
     jobs: {
       "v3.deliverAlert": async ({ payload }) => {
         const service = new DeliverAlertService();

apps/webapp/app/v3/commonWorker.server.ts

@@ -196,7 +196,7 @@ function initializeWorker() {
     pollIntervalMs: env.COMMON_WORKER_POLL_INTERVAL,
     immediatePollIntervalMs: env.COMMON_WORKER_IMMEDIATE_POLL_INTERVAL,
     shutdownTimeoutMs: env.COMMON_WORKER_SHUTDOWN_TIMEOUT_MS,
-    logger: new Logger("CommonWorker", "debug"),
+    logger: new Logger("CommonWorker", env.COMMON_WORKER_LOG_LEVEL),
     jobs: {
       scheduleEmail: async ({ payload }) => {
         await sendEmail(payload);

apps/webapp/app/v3/legacyRunEngineWorker.server.ts

@@ -68,7 +68,7 @@ function initializeWorker() {
     pollIntervalMs: env.LEGACY_RUN_ENGINE_WORKER_POLL_INTERVAL,
     immediatePollIntervalMs: env.LEGACY_RUN_ENGINE_WORKER_IMMEDIATE_POLL_INTERVAL,
     shutdownTimeoutMs: env.LEGACY_RUN_ENGINE_WORKER_SHUTDOWN_TIMEOUT_MS,
-    logger: new Logger("LegacyRunEngineWorker", "debug"),
+    logger: new Logger("LegacyRunEngineWorker", env.LEGACY_RUN_ENGINE_WORKER_LOG_LEVEL),
     jobs: {
       runHeartbeat: async ({ payload }) => {
         const service = new TaskRunHeartbeatFailedService();

apps/webapp/app/v3/scheduleEngine.server.ts

@@ -61,6 +61,8 @@ function createScheduleEngine() {
     },
     worker: {
       concurrency: env.SCHEDULE_WORKER_CONCURRENCY_LIMIT,
+      workers: env.SCHEDULE_WORKER_CONCURRENCY_WORKERS,
+      tasksPerWorker: env.SCHEDULE_WORKER_CONCURRENCY_TASKS_PER_WORKER,
       pollIntervalMs: env.SCHEDULE_WORKER_POLL_INTERVAL,
       shutdownTimeoutMs: env.SCHEDULE_WORKER_SHUTDOWN_TIMEOUT_MS,
       disabled: env.SCHEDULE_WORKER_ENABLED === "0",

internal-packages/run-engine/src/engine/index.ts

@@ -152,7 +152,7 @@ export class RunEngine {
       pollIntervalMs: options.worker.pollIntervalMs,
       immediatePollIntervalMs: options.worker.immediatePollIntervalMs,
       shutdownTimeoutMs: options.worker.shutdownTimeoutMs,
-      logger: new Logger("RunEngineWorker", "debug"),
+      logger: new Logger("RunEngineWorker", options.logLevel ?? "info"),
       jobs: {
         finishWaitpoint: async ({ payload }) => {
           await this.waitpointSystem.completeWaitpoint({

internal-packages/schedule-engine/src/engine/distributedScheduling.ts

@@ -5,21 +5,27 @@
  */
 export function calculateDistributedExecutionTime(
   exactScheduleTime: Date,
-  distributionWindowSeconds: number = 30
+  distributionWindowSeconds: number = 30,
+  instanceId?: string
 ): Date {
-  // Use the ISO string of the exact schedule time as the seed for consistency
-  const seed = exactScheduleTime.toISOString();
+  // Create seed by combining ISO timestamp with optional instanceId
+  // This ensures different instances get different distributions even with same schedule time
+  const timeSeed = exactScheduleTime.toISOString();
+  const seed = instanceId ? `${timeSeed}:${instanceId}` : timeSeed;
+
+  // Use a better hash function (FNV-1a variant) for more uniform distribution
+  let hash = 2166136261; // FNV offset basis (32-bit)
 
-  // Create a simple hash from the seed string
-  let hash = 0;
   for (let i = 0; i < seed.length; i++) {
-    const char = seed.charCodeAt(i);
-    hash = (hash << 5) - hash + char;
-    hash = hash & hash; // Convert to 32-bit integer
+    hash ^= seed.charCodeAt(i);
+    hash *= 16777619; // FNV prime (32-bit)
+    // Keep it as 32-bit unsigned integer
+    hash = hash >>> 0;
   }
 
-  // Convert hash to a value between 0 and 1
-  const normalized = Math.abs(hash) / Math.pow(2, 31);
+  // Convert hash to a value between 0 and 1 using better normalization
+  // Use the full 32-bit range for better distribution
+  const normalized = hash / 0xffffffff;
 
   // Calculate offset in milliseconds (0 to distributionWindowSeconds * 1000)
   const offsetMs = Math.floor(normalized * distributionWindowSeconds * 1000);

internal-packages/schedule-engine/src/engine/index.ts

@@ -92,6 +92,8 @@ export class ScheduleEngine {
       catalog: scheduleWorkerCatalog,
       concurrency: {
         limit: options.worker.concurrency,
+        workers: options.worker.workers,
+        tasksPerWorker: options.worker.tasksPerWorker,
       },
       pollIntervalMs: options.worker.pollIntervalMs,
       shutdownTimeoutMs: options.worker.shutdownTimeoutMs,
@@ -590,7 +592,8 @@ export class ScheduleEngine {
 
       const distributedExecutionTime = calculateDistributedExecutionTime(
         exactScheduleTime,
-        this.distributionWindowSeconds
+        this.distributionWindowSeconds,
+        instanceId
       );
 
       const distributionOffsetMs = exactScheduleTime.getTime() - distributedExecutionTime.getTime();

internal-packages/schedule-engine/src/engine/types.ts

@@ -35,6 +35,8 @@ export interface ScheduleEngineOptions {
   redis: RedisOptions;
   worker: {
     concurrency: number;
+    workers?: number;
+    tasksPerWorker?: number;
     pollIntervalMs?: number;
     shutdownTimeoutMs?: number;
     disabled?: boolean;

packages/redis-worker/src/worker.ts

@@ -206,7 +206,7 @@ class Worker<TCatalog extends WorkerCatalog> {
 
     // Launch a number of "worker loops" on the main thread.
     for (let i = 0; i < workers; i++) {
-      this.workerLoops.push(this.runWorkerLoop(`worker-${nanoid(12)}`, tasksPerWorker));
+      this.workerLoops.push(this.runWorkerLoop(`worker-${nanoid(12)}`, tasksPerWorker, i, workers));
     }
 
     this.setupShutdownHandlers();
@@ -390,14 +390,43 @@ class Worker<TCatalog extends WorkerCatalog> {
    * The main loop that each worker runs. It repeatedly polls for items,
    * processes them, and then waits before the next iteration.
    */
-  private async runWorkerLoop(workerId: string, taskCount: number): Promise<void> {
+  private async runWorkerLoop(
+    workerId: string,
+    taskCount: number,
+    workerIndex: number,
+    totalWorkers: number
+  ): Promise<void> {
     const pollIntervalMs = this.options.pollIntervalMs ?? 1000;
     const immediatePollIntervalMs = this.options.immediatePollIntervalMs ?? 100;
 
+    // Calculate the delay between starting each worker loop so that they don't all start at the same time.
+    const delayBetweenWorkers = this.options.pollIntervalMs ?? 1000;
+    const delay = delayBetweenWorkers * (totalWorkers - workerIndex);
+    await Worker.delay(delay);
+
+    this.logger.info("Starting worker loop", {
+      workerIndex,
+      totalWorkers,
+      delay,
+      workerId,
+      taskCount,
+      pollIntervalMs,
+      immediatePollIntervalMs,
+      concurrencyOptions: this.concurrency,
+    });
+
     while (!this.isShuttingDown) {
       // Check overall load. If at capacity, wait a bit before trying to dequeue more.
       if (this.limiter.activeCount + this.limiter.pendingCount >= this.concurrency.limit) {
+        this.logger.debug("Worker at capacity, waiting", {
+          workerId,
+          concurrencyOptions: this.concurrency,
+          activeCount: this.limiter.activeCount,
+          pendingCount: this.limiter.pendingCount,
+        });
+
         await Worker.delay(pollIntervalMs);
+
         continue;
       }
 
@@ -412,10 +441,25 @@ class Worker<TCatalog extends WorkerCatalog> {
         );
 
         if (items.length === 0) {
+          this.logger.debug("No items to dequeue", {
+            workerId,
+            concurrencyOptions: this.concurrency,
+            activeCount: this.limiter.activeCount,
+            pendingCount: this.limiter.pendingCount,
+          });
+
           await Worker.delay(pollIntervalMs);
           continue;
         }
 
+        this.logger.info("Dequeued items", {
+          workerId,
+          itemCount: items.length,
+          concurrencyOptions: this.concurrency,
+          activeCount: this.limiter.activeCount,
+          pendingCount: this.limiter.pendingCount,
+        });
+
         // Schedule each item using the limiter.
         for (const item of items) {
           this.limiter(() => this.processItem(item as AnyQueueItem, items.length, workerId)).catch(
@@ -433,6 +477,8 @@ class Worker<TCatalog extends WorkerCatalog> {
       // Wait briefly before immediately polling again since we processed items
       await Worker.delay(immediatePollIntervalMs);
     }
+
+    this.logger.info("Worker loop finished", { workerId });
   }
 
   /**