fix(Shard): EventEmitter listener warning

packages/discord.js/src/sharding/Shard.js

@@ -249,14 +249,18 @@ class Shard extends EventEmitter {
       const listener = message => {
         if (message?._fetchProp !== prop) return;
         child.removeListener('message', listener);
+        this.decrementMaxListeners(child);
         this._fetches.delete(prop);
         if (!message._error) resolve(message._result);
         else reject(Util.makeError(message._error));
       };
+
+      this.incrementMaxListeners(child);
       child.on('message', listener);
 
       this.send({ _fetchProp: prop }).catch(err => {
         child.removeListener('message', listener);
+        this.decrementMaxListeners(child);
         this._fetches.delete(prop);
         reject(err);
       });
@@ -288,14 +292,18 @@ class Shard extends EventEmitter {
       const listener = message => {
         if (message?._eval !== _eval) return;
         child.removeListener('message', listener);
+        this.decrementMaxListeners(child);
         this._evals.delete(_eval);
         if (!message._error) resolve(message._result);
         else reject(Util.makeError(message._error));
       };
+
+      this.incrementMaxListeners(child);
       child.on('message', listener);
 
       this.send({ _eval }).catch(err => {
         child.removeListener('message', listener);
+        this.decrementMaxListeners(child);
         this._evals.delete(_eval);
         reject(err);
       });
@@ -406,6 +414,30 @@ class Shard extends EventEmitter {
 
     if (respawn) this.spawn(timeout).catch(err => this.emit('error', err));
   }
+
+  /**
+   * Increments max listeners by one for a given emitter, if they are not zero.
+   * @param {EventEmitter|process} emitter The emitter that emits the events.
+   * @private
+   */
+  incrementMaxListeners(emitter) {
+    const maxListeners = emitter.getMaxListeners();
+    if (maxListeners !== 0) {
+      emitter.setMaxListeners(maxListeners + 1);
+    }
+  }
+
+  /**
+   * Decrements max listeners by one for a given emitter, if they are not zero.
+   * @param {EventEmitter|process} emitter The emitter that emits the events.
+   * @private
+   */
+  decrementMaxListeners(emitter) {
+    const maxListeners = emitter.getMaxListeners();
+    if (maxListeners !== 0) {
+      emitter.setMaxListeners(maxListeners - 1);
+    }
+  }
 }
 
 module.exports = Shard;

packages/discord.js/src/sharding/ShardClientUtil.js

@@ -111,13 +111,16 @@ class ShardClientUtil {
       const listener = message => {
         if (message?._sFetchProp !== prop || message._sFetchPropShard !== shard) return;
         parent.removeListener('message', listener);
+        this.decrementMaxListeners(parent);
         if (!message._error) resolve(message._result);
         else reject(Util.makeError(message._error));
       };
+      this.incrementMaxListeners(parent);
       parent.on('message', listener);
 
       this.send({ _sFetchProp: prop, _sFetchPropShard: shard }).catch(err => {
         parent.removeListener('message', listener);
+        this.decrementMaxListeners(parent);
         reject(err);
       });
     });
@@ -146,13 +149,15 @@ class ShardClientUtil {
       const listener = message => {
         if (message?._sEval !== script || message._sEvalShard !== options.shard) return;
         parent.removeListener('message', listener);
+        this.decrementMaxListeners(parent);
         if (!message._error) resolve(message._result);
         else reject(Util.makeError(message._error));
       };
+      this.incrementMaxListeners(parent);
       parent.on('message', listener);
-
       this.send({ _sEval: script, _sEvalShard: options.shard }).catch(err => {
         parent.removeListener('message', listener);
+        this.decrementMaxListeners(parent);
         reject(err);
       });
     });
@@ -241,6 +246,30 @@ class ShardClientUtil {
     if (shard < 0) throw new Error('SHARDING_SHARD_MISCALCULATION', shard, guildId, shardCount);
     return shard;
   }
+
+  /**
+   * Increments max listeners by one for a given emitter, if they are not zero.
+   * @param {EventEmitter|process} emitter The emitter that emits the events.
+   * @private
+   */
+  incrementMaxListeners(emitter) {
+    const maxListeners = emitter.getMaxListeners();
+    if (maxListeners !== 0) {
+      emitter.setMaxListeners(maxListeners + 1);
+    }
+  }
+
+  /**
+   * Decrements max listeners by one for a given emitter, if they are not zero.
+   * @param {EventEmitter|process} emitter The emitter that emits the events.
+   * @private
+   */
+  decrementMaxListeners(emitter) {
+    const maxListeners = emitter.getMaxListeners();
+    if (maxListeners !== 0) {
+      emitter.setMaxListeners(maxListeners - 1);
+    }
+  }
 }
 
 module.exports = ShardClientUtil;

packages/discord.js/typings/index.d.ts

@@ -1973,6 +1973,8 @@ export class Shard extends EventEmitter {
   private _fetches: Map<string, Promise<unknown>>;
   private _handleExit(respawn?: boolean, timeout?: number): void;
   private _handleMessage(message: unknown): void;
+  private incrementMaxListeners(emitter: EventEmitter | ChildProcess): void;
+  private decrementMaxListeners(emitter: EventEmitter | ChildProcess): void;
 
   public args: string[];
   public execArgv: string[];
@@ -2006,6 +2008,8 @@ export class ShardClientUtil {
   private constructor(client: Client, mode: ShardingManagerMode);
   private _handleMessage(message: unknown): void;
   private _respond(type: string, message: unknown): void;
+  private incrementMaxListeners(emitter: EventEmitter | ChildProcess): void;
+  private decrementMaxListeners(emitter: EventEmitter | ChildProcess): void;
 
   public client: Client;
   public readonly count: number;