From 8d90171f8be6b92d7186ca84c42a0e07c2c71908 Mon Sep 17 00:00:00 2001 From: "Justin M. Keyes" Date: Fri, 16 Feb 2018 19:00:02 +0100 Subject: jobs: child proc must have a separate process-group MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit UV_PROCESS_DETACHED compels libuv:uv__process_child_init() to call setsid() in the child just after fork(). That ensures the process and its descendants are grouped in a separate session (and process group). The following jobstart() call correctly groups `sh` and `sleep` in a new session (and process-group), where `sh` is the "session leader" (and process-group leader): :call jobstart(['sh','-c','sleep 60']) SESN PGRP PID PPID Command 30383 30383 30383 3620 │ ├─ -bash 30383 31432 31432 30383 │ │ └─ nvim -u NORC 30383 31432 31433 30383 │ │ ├─ nvim -u NORC 8105 8105 8105 31432 │ │ └─ sh -c sleep 60 8105 8105 8106 8105 │ │ └─ sleep 60 closes #6530 ref: https://stackoverflow.com/q/1046933 ref: https://unix.stackexchange.com/a/404065 Helped-by: Marco Hinz Discussion ------------------------------------------------------------------------ On my linux box before this patch, the termclose_spec.lua:'kills job trapping SIGTERM' test indirectly causes cmake/busted to wait for 60s. That's because the test spawns a `sleep 60` descendant process which hangs around even after nvim exits: nvim killed the parent PID, but not PGID (process-group), so the grandchild "reparented" to init (PID 1). Session contains processes (and process-groups) which are logically part of the same "login session". Process-group is a set of logically/informally-related processes within a session; for example, shells assign a process group to each "job". Session IDs and PGIDs both have type pid_t (like PIDs). These OS-level mechanisms are, as usual, legacy accidents whose purpose is upheld by convention and folklore. We can use session-level grouping (setsid), or we could use process-group-level grouping (setpgid). Vim uses setsid() if available, otherwise setpgid(0,0). Windows ------------------------------------------------------------------------ UV_PROCESS_DETACHED on win32 sets CREATE_NEW_PROCESS_GROUP flag. But uv_kill() does not kill the process-group: https://github.com/nodejs/node/issues/3617 Ideas: - Set UV_PROCESS_DETACHED (CREATE_NEW_PROCESS_GROUP), then call GenerateConsoleCtrlEvent(CTRL_BREAK_EVENT, pid) - Maybe won't work because MSDN says "Only processes that share the same console as the calling process receive the signal." https://docs.microsoft.com/en-us/windows/console/generateconsolectrlevent But CREATE_NEW_PROCESS_GROUP creates a new console ... ref https://stackoverflow.com/q/1453520 - Group processes within a "job". libuv does that *globally* for non-detached processes: uv__init_global_job_handle. - Iterate through CreateToolhelp32Snapshot(). - https://stackoverflow.com/q/1173342 - Vim does this, see terminate_all() --- src/nvim/os/pty_process_unix.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'src/nvim/os/pty_process_unix.c') diff --git a/src/nvim/os/pty_process_unix.c b/src/nvim/os/pty_process_unix.c index 855ca2ae47..dfe2cfbb8d 100644 --- a/src/nvim/os/pty_process_unix.c +++ b/src/nvim/os/pty_process_unix.c @@ -145,8 +145,12 @@ void pty_process_teardown(Loop *loop) uv_signal_stop(&loop->children_watcher); } -static void init_child(PtyProcess *ptyproc) FUNC_ATTR_NONNULL_ALL +static void init_child(PtyProcess *ptyproc) + FUNC_ATTR_NONNULL_ALL { + // New session/process-group. #6530 + setsid(); + unsetenv("COLUMNS"); unsetenv("LINES"); unsetenv("TERMCAP"); -- cgit