[release/6.0] Close MsQuic after checking for QUIC support to free resources (#75521) #80623
Description
Description
Manual backport of #75521 (which is in turn a backport of #75163 and #75441)
Fixes #74629
Replaces #75330
cc: @wfurt
Customer Impact
Memory (and number of processes) regression in .NET 7.0 from .NET 6.0 for all applications (on Win11+/Win2022+ and Linux with OpenSsl 1.1):
Even if app is not using HTTP/3 (or QUIC), we initialize early on native MsQuic.dll which always allocates threads (2* number of logical cores). Thus, causes unnecessary resource increase even if the process does not end up using HTTP/3 at all (HTTP/3 is opt-in like HTTP/2).
The fix closes all MsQuic resources after their initialization.
The change builds on fix in msquic 2.1.1 (Helix images were updated by PR #75479).
Affected platforms include Windows 11, Windows Server 2022, many Linux platforms with msquic package installed.
Note: The same problem exists also in 6.0, but hidden under opt-in switch into HTTP/3 support. We had 1 customer with ~50-core machine who noticed that in a dump and were surprised to see so many extra threads they didn't know about / they didn't need. At minimum it will help avoid developer confusion in dump investigations in such cases.
Testing
Functional tests suite passes as part of the CI, resource consumption was checked manually.
Risk
Low, the fix consists of gracefully de-initializing MsQuic library in the process after checking QUIC support. The library is re-initialized only when actually needed.