Merge pull request #5791 from cloudflare/yagiz/fix-flaky-windows

fix flaky tests in windows

Author: anonrig

src/workerd/api/node/tests/timers-global-override-test.js

@@ -153,21 +153,23 @@ export const testClearIntervalAcceptsBothTypes = {
 };
 
 // Test that the refresh() method works correctly
+// NOTE: Using larger timing margins (200ms/100ms instead of 50ms/30ms) because
+// Windows has ~15.6ms timer resolution and significant jitter under load.
 export const testTimeoutRefresh = {
   async test() {
     let callCount = 0;
 
-    // Create a timeout that would fire in 50ms
+    // Create a timeout that would fire in 200ms
     const timeout = globalThis.setTimeout(() => {
       callCount++;
-    }, 50);
+    }, 200);
 
-    // Wait 30ms, then refresh (reset the timer)
-    await new Promise((r) => globalThis.setTimeout(r, 30));
+    // Wait 100ms, then refresh (reset the timer)
+    await new Promise((r) => globalThis.setTimeout(r, 100));
     timeout.refresh();
 
-    // Wait another 30ms (total 60ms from start, but only 30ms from refresh)
-    await new Promise((r) => globalThis.setTimeout(r, 30));
+    // Wait another 100ms (total 200ms from start, but only 100ms from refresh)
+    await new Promise((r) => globalThis.setTimeout(r, 100));
 
     // The callback shouldn't have fired yet since we refreshed
     strictEqual(
@@ -176,8 +178,8 @@ export const testTimeoutRefresh = {
       'Callback should not have fired yet after refresh'
     );
 
-    // Wait another 30ms for the refreshed timer to fire
-    await new Promise((r) => globalThis.setTimeout(r, 30));
+    // Wait another 150ms for the refreshed timer to fire (with margin)
+    await new Promise((r) => globalThis.setTimeout(r, 150));
 
     // Now it should have fired
     strictEqual(callCount, 1, 'Callback should have fired once');

src/workerd/api/tests/jsrpc-timing-test-tail.js

@@ -118,11 +118,14 @@ export const test = {
       );
     }
 
-    // Return should happen at least 200ms after onset (handler sleeps for 500ms)
-    if (timeToReturn < 200) {
+    // Return should happen at least 50ms after onset (handler sleeps for 500ms)
+    // NOTE: Using a lower threshold (50ms instead of 200ms) because Windows has
+    // significant timer jitter and scheduler.wait() timing assumptions don't hold
+    // reliably under load.
+    if (timeToReturn < 50) {
       throw new Error(
         `Return event (${timeToReturn}ms) happened too quickly. ` +
-          `Expected at least 200ms from onset (handler sleeps for 500ms before returning).`
+          `Expected at least 50ms from onset (handler sleeps for 500ms before returning).`
       );
     }