Description

I have a custom collection implementation which relies on IEnumerator<T>.Dispose being called in order to release a read lock, however I discovered that on serialization System.Text.Json will grab the IEnumerator<T> but does not appear to call Dispose which results in my custom collection being in a permanent ReadLocked state.

I've just switched from Newtonsoft.Json which doesn't have this issue.

Example Code: https://gist.github.com/LXGaming/862f498de548c67d0ed7d193d22d2499

Configuration

• Which version of .NET is the code running on? .NET 5
• What OS and version, and what distro if applicable? Windows 10 20H2, dotnet/runtime:5.0 Docker Image on Ubuntu 20.04
• What is the architecture (x64, x86, ARM, ARM64)? x64
• Do you know whether it is specific to that configuration? I don't believe so.
• If you're using Blazor, which web browser(s) do you see this issue in? N/A

Regression?

I don't know.

Other information

This issue can be worked around by creating a custom converter for the custom collection.

This issue is also present in several other Converters, The IEnumerator<T> is obtained in OnWriteResume