[1.17] fix memory leak (#10639)

Author: davidjumani

changelog/v1.17.25/fix-mem-lk.yaml

@@ -0,0 +1,6 @@
+changelog:
+- type: FIX
+  issueLink: https://github.com/solo-io/solo-projects/issues/7805
+  resolvesIssue: false
+  description: Fixes a memory leak caused by an indefinitely growing map
+

projects/gateway2/status/status_syncer.go

@@ -72,14 +72,23 @@ func (f *statusSyncerFactory) QueueStatusForProxies(
 
 	// queue each proxy for a given sync iteration
 	for _, proxy := range proxiesToQueue {
+		proxyKey := getProxyNameNamespace(proxy)
 		// overwrite the sync count for the proxy with the most recent sync count
-		f.resyncsPerProxy[getProxyNameNamespace(proxy)] = totalSyncCount
+		f.resyncsPerProxy[proxyKey] = totalSyncCount
 
 		// keep track of proxies to check all proxies are handled in debugger
-		f.resyncsPerIteration[totalSyncCount] = append(f.resyncsPerIteration[totalSyncCount], getProxyNameNamespace(proxy))
+		f.resyncsPerIteration[totalSyncCount] = append(f.resyncsPerIteration[totalSyncCount], proxyKey)
 	}
+
 	// the plugin registry that produced the proxies is the same for all proxies in a given sync
 	f.registryPerSync[totalSyncCount] = pluginRegistry
+
+	// Set a max value of 5 for n-5 iterations. Ideally we should only care about n-1 but playing it safe.
+	// QueueStatusForProxies sets the entries in these maps, however the `proxy_sync_id` annotation on the proxy
+	// (which is used as the map key) can change between when this method and HandleProxyReports is called.
+	// This can result in the map indefinitely growing which is what the subsequent lines aim to stem.
+	delete(f.resyncsPerIteration, totalSyncCount-5)
+	delete(f.registryPerSync, totalSyncCount-5)
 }
 
 // HandleProxyReports is a callback that applies status plugins to the proxies that have been queued
@@ -108,7 +117,9 @@ func (f *statusSyncerFactory) HandleProxyReports(ctx context.Context, proxiesWit
 			continue
 		}
 
-		if f.resyncsPerIteration[proxySyncCount] == nil {
+		if len(f.resyncsPerIteration[proxySyncCount]) == 0 {
+			// remove the key so the map does not indefinitely grow
+			delete(f.resyncsPerIteration, proxySyncCount)
 			// re-sync already happened, nothing to do
 			continue
 		} else {
@@ -119,6 +130,11 @@ func (f *statusSyncerFactory) HandleProxyReports(ctx context.Context, proxiesWit
 				}
 			}
 			f.resyncsPerIteration[proxySyncCount] = updatedList
+
+			if len(f.resyncsPerIteration[proxySyncCount]) == 0 {
+				// remove the key so the map does not indefinitely grow
+				delete(f.resyncsPerIteration, proxySyncCount)
+			}
 		}
 
 		proxiesToReport[proxySyncCount] = append(proxiesToReport[proxySyncCount], proxyWithReport)
@@ -132,7 +148,7 @@ func (f *statusSyncerFactory) HandleProxyReports(ctx context.Context, proxiesWit
 		}
 
 		// If there are no more proxies for the sync iteration, delete the sync count
-		if len(f.resyncsPerIteration) == 0 {
+		if len(f.resyncsPerIteration[syncCount]) == 0 {
 			delete(f.registryPerSync, syncCount)
 		}
 	}