net/http: should writeLoop flush data after writing the request?

[woodliu]

What version of Go are you using (go version)?

1.12.9

$ go version

Does this issue reproduce with the latest release?

Code review. Have question about the code

What operating system and processor architecture are you using (go env)?

Code review. Have question about the code

go env Output

$ go env

What did you do?

writeLoop run wr.req.Request.write to send request，when it return err==nil it will run pc.bw.Flush() to flush buffered data.
There are two ways for wr.req.Request.write returning nil

• waitForContinue return nil, the waitForContinue function will be waitForContinue, the only way waitForContinue returns false is when the persistConn close. In this case , there will no way to flush the buffered data

• bw.Flush() and return nil. So it has flushed the buffered data.(And if bw) is nil, it won‘t need to flush

What did you expect to see?

writeLoop should not run Flush()

What did you see instead?

[bcmills]

CC @bradfitz @rsc

[bradfitz]

It does this intentionally so requests with a slow/deferred Request.Body don't deadlock. I could dig through the git blame/history to link you to previous bugs with more detail, but you could too, so feel free to do so and add some notes here.

I'm going to close this, as this seemed to just be a question and not a bug report.