transport-helper, connect: use clean_on_exit to reap children on abnormal exit

When a long-running service (e.g., a source indexer) runs as PID 1
inside a container and repeatedly spawns git, git may in turn spawn
child processes such as git-remote-https or ssh. If git exits abnormally
(e.g., via exit(128) on a transport error), the normal cleanup paths
(disconnect_helper, finish_connect) are bypassed, and these children are
never waited on. The children are reparented to PID 1, which does not
reap them, so they accumulate as zombies over time.

Set clean_on_exit and wait_after_clean on child_process structs in both
transport-helper.c and connect.c so that the existing run-command
cleanup infrastructure handles reaping on any exit path. This avoids
rolling custom atexit handlers that call finish_command(), which could
deadlock if the child is blocked waiting for the parent to close a pipe.

The clean_on_exit mechanism sends SIGTERM first, then waits, ensuring
the child terminates promptly. It also handles signal-based exits, not
just atexit.

Signed-off-by: Andrew Au <cshung@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/connect.c b/connect.c
index a02583a102724120689139fd7795ff965e5c2263..fcd35c5539a76e4f694f8392615de262c5b40c6d 100644 (file)
--- a/connect.c
+++ b/connect.c
@@ -1054,6 +1054,8 @@ static struct child_process *git_proxy_connect(int fd[2], char *host)
        strvec_push(&proxy->args, port);
        proxy->in = -1;
        proxy->out = -1;
+       proxy->clean_on_exit = 1;
+       proxy->wait_after_clean = 1;
        if (start_command(proxy))
                die(_("cannot start proxy %s"), git_proxy_command);
        fd[0] = proxy->out; /* read from proxy stdout */
@@ -1515,6 +1517,8 @@ struct child_process *git_connect(int fd[2], const char *url,
                }
                strvec_push(&conn->args, cmd.buf);
 
+               conn->clean_on_exit = 1;
+               conn->wait_after_clean = 1;
                if (start_command(conn))
                        die(_("unable to fork"));
 

diff --git a/transport-helper.c b/transport-helper.c
index 4d95d84f9e4d05db5117016bcdacadf3a4fe46b2..570d7c6439569a96136b6151ff28b7f5afa2aa7b 100644 (file)
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -154,6 +154,8 @@ static struct child_process *get_helper(struct transport *transport)
 
        helper->trace2_child_class = helper->args.v[0]; /* "remote-<name>" */
 
+       helper->clean_on_exit = 1;
+       helper->wait_after_clean = 1;
        code = start_command(helper);
        if (code < 0 && errno == ENOENT)
                die(_("unable to find remote helper for '%s'"), data->name);