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net/http: data race in concurrent req.Body.{Close,Read} with 100-continue expected #30580
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See the documentation for Handler, https://golang.org/pkg/net/http/#Handler.
You are violating the concurrently rule. |
Thanks @fraenkel, I investigated a bit further and found that the data race and nil pointer dereference are not the same underlying issue. The data race can be triggered by any handler that concurrently calls |
I agree with @fraenkel that this isn't a bug because this code is violating the rules: srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
go r.Body.Read(make([]byte, 1024))
go r.Body.Close()
})) |
@bradfitz please have another look at this sample code, it triggers the race detector I think without violating the rules: srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
var wg sync.WaitGroup
wg.Add(2)
go func() { r.Body.Read(make([]byte, 1024)); wg.Done() }()
go func() { r.Body.Close(); wg.Done() }()
wg.Wait()
})) |
Thanks. I'm not sure concurrent Read & Close is legal in this context, but maybe it should be. I'll use this bug to investigate and either fix or document. |
Its a bit more than just Read & Close. Just for kicks I modified the example to do concurrent reads of 1 byte.
|
The problem with Adding a simple lock would solve he problem:
I'm not sure it's the right way. cc @bradfitz |
We're running https://github.com/fabiolb/fabio as a load balancing solution and we are seeing this panic happening whenever we have concurrent requests to the same Host and path and sending the |
Is this related to #26253 ? |
@bradfitz what do you think about @cuonglm's suggestion in #30580 (comment)? @cuonglm would you like to send a CL to get the train rolling? Thank you! |
Please answer these questions before submitting your issue. Thanks!
What did you do?
https://gist.github.com/benburkert/76548cfac5aa6761fab2f88783b673aa
What did you expect to see?
No output.
What did you see instead?
System details
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