[System.Net.Http.Json] HttpClient not always calling HttpContent.LoadIntoBufferAsync

[danielgerlag]

Description

When doing a Post with HttpClient and using JsonContent, I noticed that sometimes an empty body is posted. When I drilled into it, I found that if I explicitly call LoadIntoBufferAsync() on the HttpContent then the issue goes away and everything works fine.

var content = JsonContent.Create(data);
await content.LoadIntoBufferAsync();  //without this, it doesn't always work
await _httpClient.PostAsync(item.CallBack, content);

Configuration

.net core 3.1
System.Net.Http.Json, Version=5.0.0.0

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Issue Details

---

Description

When doing a Post with HttpClient and using JsonContent, I noticed that sometimes an empty body is posted. When I drilled into it, I found that if I explicitly call LoadIntoBufferAsync() on the HttpContent then the issue goes away and everything works fine.

var content = JsonContent.Create(data);
await content.LoadIntoBufferAsync();  //without this, it doesn't always work
await _httpClient.PostAsync(item.CallBack, content);

Configuration

.net core 3.1
System.Net.Http.Json, Version=5.0.0.0

Author:	danielgerlag
Assignees:	-
Labels:	area-System.Net.Http, untriaged
Milestone:	-

[karelz]

@eiriktsarpalis @layomia @steveharter can you please help triage this issue? Thanks!

[eiriktsarpalis]

That's surprising, since on quick inspection it seems like HttpClient will also call LoadIntoBufferAsync eventually. Could you provide a minimal reproduction that demonstrates the issue?

.net core 3.1
System.Net.Http.Json, Version=5.0.0.0

I can't help noticing that you're running a v5 library on .NET Core 3.1. I believe JsonContent was added in 5 so I wouldn't be too surprised if it depended on implementation details of the v5 HttpClient.

[danielgerlag]

It's not deterministic, bigger payloads are more likely to be sent as empty, so I suspect the LoadIntoBufferAsync is not being awaited somewhere, causing a race condition.

[eiriktsarpalis]

Are you able to verify that the same behaviour reproduces on .NET 5?