core(network-monitor): treat EventSource as non-critical

core/gather/driver/network-monitor.js

@@ -129,7 +129,7 @@ class NetworkMonitor extends NetworkMonitorEventEmitter {
    * Returns whether the network is completely idle (i.e. there are 0 inflight network requests).
    */
   isIdle() {
-    return this._isActiveIdlePeriod(0);
+    return this._isIdlePeriod(0);
   }
 
   /**
@@ -144,10 +144,13 @@ class NetworkMonitor extends NetworkMonitorEventEmitter {
     const rootFrameRequest = requests.find(r => r.resourceType === 'Document');
     const rootFrameId = rootFrameRequest?.frameId;
 
-    return this._isActiveIdlePeriod(
+    return this._isIdlePeriod(
       0,
+      // Return true if it should be a candidate for critical.
       request =>
         request.frameId === rootFrameId &&
+        // WebSocket and Server-sent Events are typically long-lived and shouldn't be considered critical.
+        request.resourceType !== 'WebSocket' && request.resourceType !== 'EventSource' &&
         (request.priority === 'VeryHigh' || request.priority === 'High')
     );
   }
@@ -156,7 +159,7 @@ class NetworkMonitor extends NetworkMonitorEventEmitter {
    * Returns whether the network is semi-idle (i.e. there are 2 or fewer inflight network requests).
    */
   is2Idle() {
-    return this._isActiveIdlePeriod(2);
+    return this._isIdlePeriod(2);
   }
 
   /**
@@ -166,15 +169,15 @@ class NetworkMonitor extends NetworkMonitorEventEmitter {
    * @param {(request: NetworkRequest) => boolean} [requestFilter]
    * @return {boolean}
    */
-  _isActiveIdlePeriod(allowedRequests, requestFilter) {
+  _isIdlePeriod(allowedRequests, requestFilter) {
     if (!this._networkRecorder) return false;
     const requests = this._networkRecorder.getRawRecords();
     let inflightRequests = 0;
 
     for (let i = 0; i < requests.length; i++) {
       const request = requests[i];
       if (request.finished) continue;
-      if (requestFilter && !requestFilter(request)) continue;
+      if (requestFilter?.(request) === false) continue;
       if (NetworkRequest.isNonNetworkRequest(request)) continue;
       inflightRequests++;
     }

core/test/gather/driver/network-monitor-test.js

@@ -359,6 +359,22 @@ describe('NetworkMonitor', () => {
       expect(monitor.is2Idle()).toBe(false);
       expect(monitor.isCriticalIdle()).toBe(true);
     });
+
+    it('should treat longlived stuff as noncritical', () => {
+      const messages = networkRecordsToDevtoolsLog([
+        // WebSockets usually dont have a priority on them. SSE usually is a 'High'
+        {url: 'http://example.com/ws', priority: undefined, requestId: `314.1`, resourceType: 'WebSocket'},
+        {url: 'http://example.com/sse', priority: 'High', requestId: `314.2`, resourceType: 'EventSource'},
+      ], {skipVerification: true}).filter(event => event.method === 'Network.requestWillBeSent');
+
+      for (const message of messages) {
+        rootDispatch(message);
+      }
+
+      expect(monitor.isCriticalIdle()).toBe(true);
+      expect(monitor.isIdle()).toBe(false);
+      expect(monitor.is2Idle()).toBe(true);
+    });
   });
 
   describe('#findNetworkQuietPeriods', () => {