[Lldb-commits] [lldb] [LLDB][ProcessWindows] Set exit status on instance rather than going through all targets (PR #159308)

[via lldb-commits]

https://github.com/Nerixyz created https://github.com/llvm/llvm-project/pull/159308

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:
https://github.com/llvm/llvm-project/blob/88c64f76ed2ca226da99b99f60d316b1519fc7d8/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:
https://github.com/llvm/llvm-project/blob/88c64f76ed2ca226da99b99f60d316b1519fc7d8/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`](https://github.com/llvm/llvm-project/blob/88c64f76ed2ca226da99b99f60d316b1519fc7d8/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp#L656-L673). This calls the static function [`Process::SetProcessExitStatus`](https://github.com/llvm/llvm-project/blob/0a7a7d56fc882653335beba0d1f8ea9f26089c22/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 on 
https://github.com/llvm/llvm-project/blob/0a7a7d56fc882653335beba0d1f8ea9f26089c22/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.

>From 5fc496d61a9cd54ac00060da419e91e274f2bc1f Mon Sep 17 00:00:00 2001
From: Nerixyz <nerixdev at outlook.de>
Date: Wed, 17 Sep 2025 11:40:43 +0200
Subject: [PATCH] [LLDB][ProcessWindows] Set exit status on instance rather
 than going through all targets

---
 lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
index 27530f032ce51..0fecefe23b88e 100644
--- a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
+++ b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
@@ -666,7 +666,7 @@ void ProcessWindows::OnExitProcess(uint32_t exit_code) {
     target->ModulesDidUnload(unloaded_modules, true);
   }
 
-  SetProcessExitStatus(GetID(), true, 0, exit_code);
+  SetExitStatus(exit_code, /*exit_string=*/"");
   SetPrivateState(eStateExited);
 
   ProcessDebugger::OnExitProcess(exit_code);