Fix job assignment timing issue by queuing jobs in backend when worker not registered

vidai/backend.py

@@ -27,6 +27,7 @@ from .queue import queue_manager
 
 
 worker_sockets = {}  # type: dict
+pending_jobs = {}  # worker_key -> list of messages
 pending_results = {}  # msg_id -> result message
 job_progress = {}  # job_id -> progress data
 job_progress_times = {}  # job_id -> last_progress_timestamp
@@ -75,8 +76,11 @@ def handle_web_message(message: Message, client_sock=None) -> Message:
             print(f"Backend sent to worker {worker_key}")
             return Message('success', message.msg_id, {'status': 'forwarded'})
         else:
-            print(f"Backend: Worker {worker_key} not found in worker_sockets")
-            return Message('error', message.msg_id, {'error': f'Worker {worker_key} not available'})
+            print(f"Backend: Worker {worker_key} not found in worker_sockets, queuing job")
+            if worker_key not in pending_jobs:
+                pending_jobs[worker_key] = []
+            pending_jobs[worker_key].append(message)
+            return Message('success', message.msg_id, {'status': 'queued'})
     elif message.msg_type == 'train_request':
         backend = get_training_backend()
         worker_key = f'training_{backend}'
@@ -143,6 +147,24 @@ def handle_worker_message(message: Message, client_sock) -> None:
             print(f"Worker {worker_type} registered")
             print(f"DEBUG: worker_sockets keys after register: {list(worker_sockets.keys())}")
 
+            # Send any pending jobs for this worker
+            if worker_type in pending_jobs:
+                import json
+                for pending_msg in pending_jobs[worker_type]:
+                    msg_dict = {
+                        'msg_type': pending_msg.msg_type,
+                        'msg_id': pending_msg.msg_id,
+                        'data': pending_msg.data
+                    }
+                    msg_json = json.dumps(msg_dict) + '\n'
+                    print(f"Backend sending pending job to worker {worker_type}: {msg_json.strip()}")
+                    try:
+                        worker_sockets[worker_type].sendall(msg_json.encode('utf-8'))
+                        print(f"Backend sent pending job to worker {worker_type}")
+                    except Exception as e:
+                        print(f"Failed to send pending job to worker {worker_type}: {e}")
+                del pending_jobs[worker_type]
+
             # Notify cluster master that a worker has registered
             try:
                 import socket