[PATCH] run-command: don't spam trace2_child_exit()

[Josh Steadmon <steadmon@google.com>]

In rare cases, wait_or_whine() cannot determine a child process's exit
status (and will return -1 in this case). This can cause Git to issue
trace2 child_exit events despite the fact that the child is still
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().

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 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;
 }
 

base-commit: faa21c10d44184f616d391c158dcbb13b9c72ef3
-- 
2.36.0.464.gb9c8b46e94-goog