客户端子进程请求服务端会卡死

**Describe the bug (描述bug)**
你好， 我现在遇到一个问题。 我用客户端请求服务端，让服务端创建了个子进程，然后在子进程另起了一个服务， 然后客户端再创建一个子进程，去请求这个子进程创建的server， 但是这时候就会卡死， 客户端一直收不到回包， 而服务端能看到tcp已经连接成功了，请问这是什么情况？？？

**To Reproduce (复现方法)**

**Expected behavior (期望行为)**

**Versions (各种版本)**
OS:
Compiler:
brpc:
protobuf:

**Additional context/screenshots (更多上下文/截图)**

No file, test, entry point, or usable version information is provided. Start by reproducing the client/server subprocess sequence and record the OS, compiler, brpc, and protobuf versions; done means the client receives the response instead of hanging after the TCP connection succeeds.

Written by the indexing model from the issue text.