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.

Start by reproducing the example around rmq_consumer, send_message, start_pro, and producer.send_sync, comparing the direct callback path with the Process(target=start_pro) path. Trace the producer startup and topic route lookup in the Python client and its RocketMQ client dependency. Done means identifying why the child process receives no route info for fireMsg and documenting a verified cause or correction.

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