improving event loop handling

src/backend/model/EventLoopHandler.ts

@@ -0,0 +1,19 @@
+export class EventLoopHandler {
+
+  private eventCounter = 0;
+
+  constructor(private readonly MAX_LOOP = 10) {
+  }
+
+  /*
+  * setImmediate is slow, but does the right thing
+  * next tick is super fast, but does not help much with the event loop as it does not allow a full event loop cycle
+  * https://medium.com/dkatalis/eventloop-in-nodejs-settimeout-setimmediate-vs-process-nexttick-37c852c67acb
+  * */
+  step(fn: () => Promise<void> | void) {
+
+    this.eventCounter = this.eventCounter % 10;
+    const eventFN = this.eventCounter++ === 1 ? setImmediate : process.nextTick;
+    eventFN(fn);
+  }
+}

src/backend/model/jobs/jobs/Job.ts

@@ -134,6 +134,7 @@ export abstract class Job<T extends Record<string, unknown> = Record<string, unk
   }
 
   private run(): void {
+    // we call setImmediate later.
     process.nextTick(async (): Promise<void> => {
       try {
         if (

src/backend/model/threading/TaskExecuter.ts

@@ -1,4 +1,5 @@
 import {TaskQue} from './TaskQue';
+import {EventLoopHandler} from '../EventLoopHandler';
 
 export interface ITaskExecuter<I, O> {
   execute(input: I): Promise<O>;
@@ -7,6 +8,7 @@ export interface ITaskExecuter<I, O> {
 export class TaskExecuter<I, O> implements ITaskExecuter<I, O> {
   private taskQue = new TaskQue<I, O>();
   private taskInProgress = 0;
+  private readonly el = new EventLoopHandler();
   private run = async () => {
     if (this.taskQue.isEmpty() || this.taskInProgress >= this.size) {
       return;
@@ -20,7 +22,7 @@ export class TaskExecuter<I, O> implements ITaskExecuter<I, O> {
     }
     this.taskQue.ready(task);
     this.taskInProgress--;
-    process.nextTick(this.run);
+    this.el.step(this.run);
   };
 
   constructor(private size: number, private worker: (input: I) => Promise<O>) {