lib: optimize writable stream buffer clearing

ri7116 · aduh95 · commit d22d2fa6d4d7 · 2025-08-26T11:22:41.000+02:00
Improved the `clearBuffer` function by replacing `buffered.splice` with `ArrayPrototypeSlice`. - Eliminates O(N) shifting overhead. - Improves CPU utilization and reduces GC overhead. PR-URL: #59406 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Ethan Arrowood <ethan@arrowood.dev> Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Anna Henningsen <anna@addaleax.net>
diff --git a/lib/internal/streams/writable.js b/lib/internal/streams/writable.js
@@ -786,7 +786,7 @@ function clearBuffer(stream, state) {
     if (i === buffered.length) {
       resetBuffer(state);
     } else if (i > 256) {
-      buffered.splice(0, i);
+      state[kBufferedValue] = ArrayPrototypeSlice(buffered, i);
       state.bufferedIndex = 0;
     } else {
       state.bufferedIndex = i;
