Ghostty hangs when trying to close the window.

[rockorager]

Version

Ghostty 1.0.2-main+12ce9f2e3b19

Issue

Ghostty hangs when multiple tabs (or windows, if gtk-single-instance=true) are open and one attempts to close the window via a Close Window request over wayland. This is distinct from clicking the close tab button, or other internal close methods.

I bisected this to 3e24e96 (#4171).

Repro steps

Using GNOME:

1. Add a keybind for Close Window (Alt+F4 is default in GNOME)
2. Open Ghostty
3. Open a new tab
4. Press keybind for Close Window

[rockorager]

This diff fixes it for me, but it seems like the motiviation for #4171 was to not write to the pipe. So I guess the question is why does my poll not return when the write end of the pipe closes? IME, this has always been the case: closing a file descriptor does not cause the poll to exit.

If we must prevent writes to the poll, we either need to have a timeout on the poll and periodically check for HUP or do something else. This has rendered ghostty unusable for me.

diff --git a/src/termio/Exec.zig b/src/termio/Exec.zig
index d409ccbb0423..ae7a5203c416 100644
--- a/src/termio/Exec.zig
+++ b/src/termio/Exec.zig
@@ -180,6 +180,8 @@ pub fn threadExit(self: *Exec, td: *termio.Termio.ThreadData) void {
     // we don't get stuck waiting for data to stop flowing if it is
     // a particularly noisy process.
     if (exec.read_thread_pipe) |pipe| {
+        _ = posix.write(pipe, "x") catch |err|
+            log.warn("error writing to read thread quit pipe err={}", .{err});
         posix.close(pipe);
         // Tell deinit that we've already closed the pipe
         exec.read_thread_pipe = null;
@@ -1454,8 +1456,10 @@ pub const ReadThread = struct {
                 return;
             };
 
-            // If our quit fd is closed, we're done.
-            if (pollfds[1].revents & posix.POLL.HUP != 0) {
+            // If our quit fd is closed or has data available, we're done.
+            if (pollfds[1].revents & posix.POLL.HUP != 0 or
+                pollfds[1].revents & posix.POLL.IN != 0)
+            {
                 log.info("read thread got quit signal", .{});
                 return;
             }

[jcollie]

I can reproduce using Alt+F4 to close a Ghostty window with 2 tabs open. This is the debug log from just before the hang.

debug(renderer_thread): starting renderer thread shutdown
debug(renderer_thread): renderer thread exited
debug(io_thread): starting IO thread shutdown
debug(io_exec): process group killed pgid=1215269
debug(io_exec): waitpid result=0
debug(io_exec): process group killed pgid=1215269
debug(io_exec): waitpid result=1215269

[erka]

Today I had the similar situation. I had two tabs and run exit in shell in one of them

[rhodes-b]

#4838 is another example of this

[mitchellh]

This was fixed through reverting the problematic commit and I opend an issued to track the original issue we were trying to fix.