When the channel is empty, the request will be blocked

[funky-eyes]

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Ⅰ. Issue Description

Ⅱ. Describe what happened

If there is an exception, please attach the exception trace:

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Ⅲ. Describe what you expected to happen

Ⅳ. How to reproduce it (as minimally and precisely as possible)

1. xxx
2. xxx
3. xxx

Minimal yet complete reproducer code (or URL to code):

Ⅴ. Anything else we need to know?

Ⅵ. Environment:

• JDK version(e.g. java -version):
• Seata client/server version:
• Database version:
• OS(e.g. uname -a):
• Others: