fix: deduplicate getSid() listeners to prevent leak on concurrent calls

.changeset/tall-birds-rest.md

@@ -0,0 +1,5 @@
+---
+'@livekit/rtc-node': patch
+---
+
+Deduplicate getSid() listeners to prevent event listener leak on concurrent calls

packages/livekit-rtc/src/room.ts

@@ -131,6 +131,11 @@ export class Room extends (EventEmitter as new () => TypedEmitter<RoomCallbacks>
     return this._serverUrl;
   }
 
+  // Shared promise for concurrent getSid() callers. Without this, each call
+  // registers its own RoomSidChanged + Disconnected listeners, and if many
+  // calls race only one of each pair is cleaned up — leaking the rest.
+  private sidPromise?: Promise<string>;
+
   /**
    * Gets the room's server ID. This ID is assigned by the LiveKit server
    * and is unique for each room session.
@@ -144,19 +149,26 @@ export class Room extends (EventEmitter as new () => TypedEmitter<RoomCallbacks>
     if (this.info?.sid && this.info.sid !== '') {
       return this.info.sid;
     }
-    return new Promise((resolve, reject) => {
-      const handleRoomUpdate = (sid: string) => {
-        if (sid !== '') {
+    if (!this.sidPromise) {
+      this.sidPromise = new Promise<string>((resolve, reject) => {
+        const handleDisconnect = () => {
           this.off(RoomEvent.RoomSidChanged, handleRoomUpdate);
-          resolve(sid);
-        }
-      };
-      this.on(RoomEvent.RoomSidChanged, handleRoomUpdate);
-      this.once(RoomEvent.Disconnected, () => {
-        this.off(RoomEvent.RoomSidChanged, handleRoomUpdate);
-        reject('Room disconnected before room server id was available');
+          this.sidPromise = undefined;
+          reject('Room disconnected before room server id was available');
+        };
+        const handleRoomUpdate = (sid: string) => {
+          if (sid !== '') {
+            this.off(RoomEvent.RoomSidChanged, handleRoomUpdate);
+            this.off(RoomEvent.Disconnected as any, handleDisconnect);
+            this.sidPromise = undefined;
+            resolve(sid);
+          }
+        };
+        this.on(RoomEvent.RoomSidChanged, handleRoomUpdate);
+        this.once(RoomEvent.Disconnected, handleDisconnect);
       });
-    });
+    }
+    return this.sidPromise;
   }
 
   get numParticipants(): number {
@@ -283,6 +295,10 @@ export class Room extends (EventEmitter as new () => TypedEmitter<RoomCallbacks>
       return ev.message.case == 'disconnect' && ev.message.value.asyncId == res.asyncId;
     });
 
+    // Clear sidPromise before removing listeners so that a reconnect
+    // doesn't return a stale, permanently-pending promise.
+    this.sidPromise = undefined;
+
     FfiClient.instance.removeListener(FfiClientEvent.FfiEvent, this.onFfiEvent);
     this.removeAllListeners();
   }

packages/livekit-rtc/src/tests/e2e.test.ts

@@ -514,4 +514,24 @@ describeE2E('livekit-rtc e2e', () => {
     },
     testTimeoutMs * 2,
   );
+
+  it(
+    'concurrent getSid() calls share a single listener and resolve consistently',
+    async () => {
+      const { rooms } = await connectTestRooms(1);
+      const room = rooms[0]!;
+
+      // Fire multiple concurrent getSid() calls — they should all resolve
+      // to the same SID without leaking event listeners.
+      const results = await Promise.all([room.getSid(), room.getSid(), room.getSid()]);
+
+      // All calls should return the same non-empty SID
+      expect(results[0]).toBeTruthy();
+      expect(results[1]).toBe(results[0]);
+      expect(results[2]).toBe(results[0]);
+
+      await room.disconnect();
+    },
+    testTimeoutMs,
+  );
 });