Why has the chat interface/v1/chat/completions been modified to serial

In previous versions of Git, the chat interface /v1/chat/completions was tested. By outputting logs, it was found that when multiple threads called this interface, the logs immediately output information, proving that multiple threads had called and entered this interface. The resulting lag was due to the lag in the response generated by the large model when FastChat called the chat interface of the large model. However, the interface/v1/chat/completions did not intercept any requests. In the current version of Git, multithreaded calls to the/v1/chat/completions interface require a response from one thread before another thread can access the interface. Is there a serial restriction on this interface? What is the purpose and purpose of doing so?

Start by tracing the current /v1/chat/completions request handling and compare it with the earlier version described in the issue. Reproduce concurrent calls while inspecting logs to determine where serialization occurs; done means documenting whether the restriction is intentional, its purpose, and the relevant behavior or fix.