fix: check batch size before re-queueing retried messages

src/message-queues.ts

@@ -287,11 +287,30 @@ export abstract class MessageQueue {
       return;
     }
 
+    // If we'd go over maxMessages or MAX_BATCH_BYTES by re-queueing this
+    // message, flush first
+    const {maxMessages} = this._options;
+    const size = Buffer.byteLength(message.message.ackId, 'utf8');
+    if (
+      this._requests.length + 1 >= maxMessages! ||
+      this.bytes + size >= MAX_BATCH_BYTES
+    ) {
+      const reason =
+        this._requests.length + 1 >= maxMessages!
+          ? 'going over count'
+          : 'going over size';
+
+      // No need to wait on this one; it clears the old batch out, and acks
+      // are best effort.
+      this.flush(reason).catch(() => {});
+    }
+
     // Just throw it in for another round of processing on the next batch.
     this._requests.push(message);
     this.numPendingRequests++;
     this.numInFlightRequests++;
     this.numInRetryRequests--;
+    this.bytes += size;
 
     // Make sure we actually do have another batch scheduled.
     if (!this._timer) {