lldb-dap 19+ hangs on Windows

[SuibianP]

Summary

Since 19.1.0 release, official lldb-dap binary releases has been hanging on Windows.

Symptom

• Neither locally built Debug nor RelWithDbgInfo builds exhibits the same issue; only the official binaries does
• Launching lldb-dap on the terminal, interactively inputting lines then Ctrl-C: No input is consumed
• Launching lldb-dap with -p: TCP port is not opened
• VSCode LLDB-DAP extension or emacs dape: Hangs and times out respectively
• LLDBDAP_LOG file gets created but is empty
• Running under WinDbg: Nondeterministic behaviour
  • Same issue as above
  • Fatal Python error: can’t initialize sys standard streams
  • Working correctly

Suspected cause

The issue may be related to Python in some way, as the system Python version (that local builds link against?) differs from the version used by official binaries (3.10 embeddable package). More specifically, I speculate it might be some race condition between Python init_sys_streams and lldb-dap _setmode call inside DAP constructor.

Furum reports

https://discourse.llvm.org/t/lldb-dap-frozen-on-windows/83652

https://discourse.llvm.org/t/lldb-dap-in-vscode/83771