From ce3986bb224067ecdb372d7cb7a56d22682e9a31 Mon Sep 17 00:00:00 2001 From: Josh Steadmon Date: Tue, 7 Jun 2022 11:21:57 -0700 Subject: [PATCH] run-command: don't spam trace2_child_exit() In rare cases[1], wait_or_whine() cannot determine a child process's status (and will return -1 in this case). This can cause Git to issue trace2 child_exit events despite the fact that the child may still be running. In pathological cases, we've seen > 80 million exit events in our trace logs for a single child process. Fix this by only issuing trace2 events in finish_command_in_signal() if we get a value other than -1 from wait_or_whine(). This can lead to missing child_exit events in such a case, but that is preferable to duplicating events on a scale that threatens to fill the user's filesystem with invalid trace logs. [1]: This can happen when: * waitpid() returns -1 and errno != EINTR * waitpid() returns an invalid PID * the status set by waitpid() has neither the WIFEXITED() nor WIFSIGNALED() flags Signed-off-by: Josh Steadmon Signed-off-by: Junio C Hamano --- run-command.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/run-command.c b/run-command.c index a8501e38ce..e0fe2418a2 100644 --- a/run-command.c +++ b/run-command.c @@ -983,7 +983,8 @@ int finish_command(struct child_process *cmd) int finish_command_in_signal(struct child_process *cmd) { int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 1); - trace2_child_exit(cmd, ret); + if (ret != -1) + trace2_child_exit(cmd, ret); return ret; }