llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-lldb
Author: Nerixyz (Nerixyz)
<details>
<summary>Changes</summary>
I noticed that LLDB takes longer to stop than it should. Running a tiny program
like `int main() { return 0; }` in LLDB with `lldb test.exe -o r -o q` takes
about five seconds.
This is caused by the `WaitForMultipleObjects` in
[`ConnectionGenericFile::Read`](https://github.com/llvm/llvm-project/blob/25976e83606f1a7615e3725e6038bb53ee96c3d5/lldb/source/Host/windows/ConnectionGenericFileWindows.cpp#L191-L192)
timing out (it has a timeout of 5s).
It times out, because we never close the PTY created in
[`ProcessLaunchInfo::SetUpPtyRedirection`](https://github.com/llvm/llvm-project/blob/25976e83606f1a7615e3725e6038bb53ee96c3d5/lldb/source/Host/common/ProcessLaunchInfo.cpp#L213).
When we call `target->GetProcessLaunchInfo().GetPTY().Close()` in
`ProcessWindows::OnExitProcess`, we don't access the PTY we created when
setting up the redirection - we're closing some default constructed one. This
is because the target's `m_launch_info` isn't the `launch_info` we get in
[`Target::FinalizeFileActions`](https://github.com/llvm/llvm-project/blob/4a8a0593bdecee49331cb5c31a6c9b18d87ea41c/lldb/source/Target/Target.cpp#L3850)
when calling `SetUpPtyRedirection`.
With this PR, we store the PTY that a process was launched with inside
`ProcessWindows`, so we can later close it.
The wait of five seconds and a timed out `WaitForMultipleObjects` sounds
similar to https://github.com/llvm/llvm-project/pull/159308, but it's a
different call to `WaitForMultipleObjects` here. Still, I wonder if we could do
something to detect this earlier. Maybe some warning message or debug-only
assert if these waits time out?
---
Full diff: https://github.com/llvm/llvm-project/pull/175837.diff
2 Files Affected:
- (modified) lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
(+4-1)
- (modified) lldb/source/Plugins/Process/Windows/Common/ProcessWindows.h (+1)
``````````diff
diff --git a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
index 127dd0f59e9ae..226cc147aadae 100644
--- a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
+++ b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
@@ -214,6 +214,7 @@ Status ProcessWindows::DoLaunch(Module *exe_module,
error = LaunchProcess(launch_info, delegate);
if (error.Success())
SetID(launch_info.GetProcessID());
+ m_pty = launch_info.GetPTYSP();
return error;
}
@@ -650,8 +651,10 @@ void ProcessWindows::OnExitProcess(uint32_t exit_code) {
Log *log = GetLog(WindowsLog::Process);
LLDB_LOG(log, "Process {0} exited with code {1}", GetID(), exit_code);
+ if (m_pty)
+ m_pty->Close();
+
TargetSP target = CalculateTarget();
- target->GetProcessLaunchInfo().GetPTY().Close();
if (target) {
ModuleSP executable_module = target->GetExecutableModule();
ModuleList unloaded_modules;
diff --git a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.h
b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.h
index 33e4de6b85932..becab6964a4aa 100644
--- a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.h
+++ b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.h
@@ -117,6 +117,7 @@ class ProcessWindows : public Process, public
ProcessDebugger {
};
std::map<lldb::break_id_t, WatchpointInfo> m_watchpoints;
std::vector<lldb::break_id_t> m_watchpoint_ids;
+ std::shared_ptr<PTY> m_pty;
};
} // namespace lldb_private
``````````
</details>
https://github.com/llvm/llvm-project/pull/175837
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