[BUG]: CMMU crashes if send 20+ write request at once

[duc0905]

Describe the bug
I am benchmarking the system, and the Agent is frozen when I send 20+ requests in parallel.
CMMU sagfaults.

Expected behavior
Expect it to queue up the requests or rejects them.

To Reproduce
Steps to reproduce the behavior:

1. Set up a DFS consisting of 1 CMMU and 1 Agent
2. Write a script that send 25 requests in parallel to the agent
3. Run the script, pass in a file, relatively small, about 1.8KB

Additional context
Add any other context about the problem here.