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 <steadmon@xxxxxxxxxx>
---
Updated the commit message with more details about when wait_or_whine()
can fail.
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
--
2.36.1.255.ge46751e96f-goog
