revert gc observer

server/src/utils/memoryMonitor.ts

@@ -5,7 +5,7 @@
  * Uses Axiom logger so metrics are queryable via type: "memory_log".
  */
 
-import { monitorEventLoopDelay, PerformanceObserver } from "node:perf_hooks";
+import { monitorEventLoopDelay } from "node:perf_hooks";
 import { logger } from "../external/logtail/logtailUtils.js";
 
 // Event loop lag histogram — samples at 100ms resolution at the C++ level.
@@ -13,21 +13,6 @@ import { logger } from "../external/logtail/logtailUtils.js";
 const lagHistogram = monitorEventLoopDelay({ resolution: 100 });
 lagHistogram.enable();
 
-// GC pause tracking. observes V8 GC events and accumulates count, max and total
-// pause duration. Reset alongside the lag histogram on each emit so windows align.
-let gcCount = 0;
-let gcMaxMs = 0;
-let gcTotalMs = 0;
-
-const gcObserver = new PerformanceObserver((list) => {
-	for (const entry of list.getEntries()) {
-		gcCount += 1;
-		gcTotalMs += entry.duration;
-		if (entry.duration > gcMaxMs) gcMaxMs = entry.duration;
-	}
-});
-gcObserver.observe({ entryTypes: ["gc"] });
-
 /** Get the current mean event loop lag in milliseconds. */
 export function getEventLoopLagMs(): number {
 	return Math.round((lagHistogram.mean / 1e6) * 10) / 10;
@@ -53,15 +38,8 @@ function logMemoryUsage(label: string) {
 	const lagMaxMs = Math.round((lagHistogram.max / 1e6) * 10) / 10;
 	lagHistogram.reset();
 
-	const localGcCount = gcCount;
-	const localGcMaxMs = Math.round(gcMaxMs * 10) / 10;
-	const localGcTotalMs = Math.round(gcTotalMs * 10) / 10;
-	gcCount = 0;
-	gcMaxMs = 0;
-	gcTotalMs = 0;
-
 	logger.info(
-		`memory_log, rss: ${toMB(mem.rss)}MB, heapUsed: ${toMB(mem.heapUsed)}MB, eventLoopLagP99: ${lagP99Ms}ms, eventLoopLagMax: ${lagMaxMs}ms, gcMax: ${localGcMaxMs}ms`,
+		`memory_log, rss: ${toMB(mem.rss)}MB, heapUsed: ${toMB(mem.heapUsed)}MB, eventLoopLagP99: ${lagP99Ms}ms, eventLoopLagMax: ${lagMaxMs}ms`,
 		{
 			type: "memory_log",
 			data: {
@@ -76,9 +54,6 @@ function logMemoryUsage(label: string) {
 				eventLoopLagMeanMs: lagMeanMs,
 				eventLoopLagP99Ms: lagP99Ms,
 				eventLoopLagMaxMs: lagMaxMs,
-				gcCount: localGcCount,
-				gcMaxMs: localGcMaxMs,
-				gcTotalMs: localGcTotalMs,
 			},
 		},
 	);