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When quitting LLDB on Windows while a process was still running, LLDB would take unusually long to exit. This was due to a temporary deadlock: The main thread was destroying the processes. In doing so, it iterated over the target list:88c64f76ed/lldb/source/Core/Debugger.cpp (L1095-L1098)This locks the list for the whole iteration. Finalizing the process would eventually lead to `DebuggerThread::StopDebugging`, which terminates the process and waits for it to exit:88c64f76ed/lldb/source/Plugins/Process/Windows/Common/DebuggerThread.cpp (L196)The debugger loop (on a separate thread) would see that the process exited and call [`ProcessWindows::OnExitProcess`](88c64f76ed/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp (L656-L673)). This calls the static function [`Process::SetProcessExitStatus`](0a7a7d56fc/lldb/source/Target/Process.cpp (L1098-L1126)). This tries to find the process by its ID from the debugger's target list. Doing so requires locking the list, so the debugger thread would then be stuck on0a7a7d56fc/lldb/source/Target/TargetList.cpp (L403)After 5s, the main thread would give up waiting. So every exit where the process was still running would be delayed by about 5s. Since `ProcessWindows` would find itself when calling `SetProcessExitStatus`, we can call `SetExitStatus` directly. This can also make some tests run faster. For example, the DIA PDB tests previously took 15s to run on my PC (24 jobs) and now take 5s. For all shell tests, the difference isn't that big (only about 3s), because most don't run into this and the tests run in parallel. (cherry picked from commit a868f28c6e9beecb2b3fbe8acfbe0d272fabd14d)