A process is launched within the callback function, and an error occurs when attempting to send an MQ message within that process.

i write a code like that:
```python
from multiprocessing import Process
from rocketmq.client import Producer, Message, PushConsumer, ConsumeStatus
import time
import json

def rmq_consumer():
consumer = PushConsumer('group_demo')
consumer.set_name_server_address('10.13.2.12:9876')
consumer.subscribe('start_or_end_detect', send_message, "*")
print(' [Consumer] Waiting for messages.')
consumer.start()
while True:
time.sleep(1)

def start_pro():
producer = Producer('test_producer')
producer.set_name_server_address('10.13.2.12:9876')
producer.start()
try:
event = {"aa": "vv", "bb": 33}
msg = Message("fireMsg")
ss = json.dumps(event).encode('utf-8')
msg.set_body(ss)
producer.send_sync(msg)

finally:
producer.shutdown()

def send_message():
i = Process(target=start_pro)
i.start()

return ConsumeStatus.CONSUME_SUCCESS

if __name__ == '__main__':
rmq_con = Process(target=rmq_consumer)
```
The code snippet "'**producer.send_sync(msg)**'"
throws an error
**"rocketmq.exceptions.ProducerSendSyncFailed: No route info of this topic: fireMsg,error:-1,in file rocketmq-client-cpp/src/producer/DefaultMQProducerImpl.cpp line:434"**

What could be the cause of this? My RocketMQ deployment is functioning normally.

**If I don't execute Process(target=start_pro) within the send_message method and instead directly include the contents of start_pro within send_message, the aforementioned error does not occur.**

Looking forward to your response. Thank you.

Comece reproduzindo o exemplo relacionado a rmq_consumer, send_message, start_pro e producer.send_sync, comparando o caminho direto do callback com o caminho Process(target=start_pro). Rastreie a inicialização do producer e a busca da rota do tópico no cliente Python e na dependência de cliente RocketMQ. Considera-se concluído quando for identificado por que o processo filho não recebe informações de rota para fireMsg e for documentada uma causa ou correção verificada.

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