♻️ [Profiler] Remove sample-count threshold from profiler discard logic (#4566)

Co-authored-by: thomas.bertet <thomas.bertet@datadoghq.com>

Author: thomasbertet

packages/rum/src/domain/profiling/profiler.spec.ts

@@ -28,7 +28,7 @@ import { mockProfiler } from '../../../test'
 import type { BrowserProfilerTrace } from '../../types'
 import { mockedTrace } from './test-utils/mockedTrace'
 import { createRumProfiler } from './profiler'
-import type { ProfilerTrace } from './types'
+import type { ProfilerTrace, RUMProfilerConfiguration } from './types'
 import type { ProfilingContextManager } from './profilingContext'
 import { startProfilingContext } from './profilingContext'
 import type { ProfileEventPayload } from './transport/assembly'
@@ -56,7 +56,7 @@ describe('profiler', () => {
 
   let lifeCycle = new LifeCycle()
 
-  function setupProfiler(currentView?: ViewHistoryEntry) {
+  function setupProfiler(currentView?: ViewHistoryEntry, profilerConfigOverrides?: Partial<RUMProfilerConfiguration>) {
     const sessionManager = createRumSessionManagerMock().setId('session-id-1')
     lifeCycle = new LifeCycle()
     const hooks = createHooks()
@@ -122,8 +122,8 @@ describe('profiler', () => {
       {
         sampleIntervalMs: 10,
         collectIntervalMs: 60000, // 1min
-        minNumberOfSamples: 0,
         minProfileDurationMs: 0,
+        ...profilerConfigOverrides,
       }
     )
     return {
@@ -933,6 +933,66 @@ describe('profiler', () => {
     expect(findTrackedSessionSpy).toHaveBeenCalledWith(expectedStartTime)
   })
 
+  describe('discard logic', () => {
+    it('should discard profile when duration is below threshold and there are no long tasks', async () => {
+      const clock = mockClock()
+      const { profiler } = setupProfiler(undefined, { minProfileDurationMs: 5000 })
+
+      profiler.start()
+      expect(profiler.isRunning()).toBe(true)
+
+      clock.tick(100)
+      profiler.stop()
+      expect(profiler.isStopped()).toBe(true)
+
+      await waitNextMicrotask()
+      await waitNextMicrotask()
+
+      expect(interceptor.requests.length).toBe(0)
+    })
+
+    it('should send profile when below duration threshold if a long task is present', async () => {
+      const clock = mockClock()
+      const { profiler, addLongTask } = setupProfiler(undefined, { minProfileDurationMs: 5000 })
+
+      profiler.start()
+      expect(profiler.isRunning()).toBe(true)
+
+      addLongTask({
+        id: 'long-task-id',
+        startClocks: clocksNow(),
+        duration: 50 as Duration,
+        entryType: RumPerformanceEntryType.LONG_ANIMATION_FRAME,
+      })
+      clock.tick(100)
+
+      profiler.stop()
+      expect(profiler.isStopped()).toBe(true)
+
+      await waitNextMicrotask()
+      await waitNextMicrotask()
+
+      expect(interceptor.requests.length).toBe(1)
+    })
+
+    it('should send profile when duration threshold is met', async () => {
+      const clock = mockClock()
+      const { profiler } = setupProfiler(undefined, { minProfileDurationMs: 100 })
+
+      profiler.start()
+      expect(profiler.isRunning()).toBe(true)
+
+      clock.tick(200)
+      profiler.stop()
+      expect(profiler.isStopped()).toBe(true)
+
+      await waitNextMicrotask()
+      await waitNextMicrotask()
+
+      expect(interceptor.requests.length).toBe(1)
+    })
+  })
+
   it('should restart profiling when session expires while paused and then renews', async () => {
     const { profiler, profilingContextManager } = setupProfiler()
 

packages/rum/src/domain/profiling/profiler.ts

@@ -31,7 +31,6 @@ import type {
   RUMProfilerConfiguration,
   RumProfilerStoppedInstance,
 } from './types'
-import { getNumberOfSamples } from './utils/getNumberOfSamples'
 import type { ProfilingContextManager } from './profilingContext'
 import { getCustomOrDefaultViewName } from './utils/getCustomOrDefaultViewName'
 import { assembleProfilingPayload } from './transport/assembly'
@@ -43,7 +42,6 @@ export const DEFAULT_RUM_PROFILER_CONFIGURATION: RUMProfilerConfiguration = {
   sampleIntervalMs: 10, // Sample stack trace every 10ms
   collectIntervalMs: 60000, // Collect data every minute
   minProfileDurationMs: 5000, // Require at least 5 seconds of profile data to reduce noise and cost
-  minNumberOfSamples: 50, // Require at least 50 samples (~500 ms) to report a profile to reduce noise and cost
 }
 
 export function createRumProfiler(
@@ -239,9 +237,8 @@ export function createRumProfiler(
         const actions = actionHistory.findAll(startClocks.relative, duration)
         const vitals = vitalHistory.findAll(startClocks.relative, duration)
         const isBelowDurationThreshold = duration < profilerConfiguration.minProfileDurationMs
-        const isBelowSampleThreshold = getNumberOfSamples(trace.samples) < profilerConfiguration.minNumberOfSamples
 
-        if (longTasks.length === 0 && (isBelowDurationThreshold || isBelowSampleThreshold)) {
+        if (longTasks.length === 0 && isBelowDurationThreshold) {
           // Skip very short profiles to reduce noise and cost, but keep them if they contain long tasks.
           return
         }

packages/rum/src/domain/profiling/types/rumProfiler.types.ts

@@ -58,5 +58,4 @@ export interface RUMProfilerConfiguration {
   sampleIntervalMs: number // Sample stack trace every x milliseconds (defaults to 10ms for Unix, 16ms on Windows)
   collectIntervalMs: number // Interval for collecting RUM Profiles (defaults to 1min)
   minProfileDurationMs: number // Minimum duration of a profile for it be sent (defaults to 5s). Profiles shorter than this duration are discarded.
-  minNumberOfSamples: number // Minimum number of samples to be collected before it can be sent (defaults to 50). Profiles with fewer samples are discarded.
 }