Subject: Re: [PATCH v2 7/8] maintenance: fix systemd schedule overlaps

From: Junio C Hamano <[email-masked]>
Date: Thu, 10 Aug 2023 14:22:16 -0700

"Derrick Stolee via GitGitGadget" <[email-masked]> writes:

> From: Derrick Stolee <[email-masked]>
>
> The 'git maintenance run' command prevents concurrent runs in the same
> repository using a 'maintenance.lock' file. However, when using systemd
> the hourly maintenance runs the same time as the daily and weekly runs.
> (Similarly, daily maintenance runs at the same time as weekly
> maintenance.) These competing commands result in some maintenance not
> actually being run.
>
> This overlap was something we could not fix until we made the recent
> change to not use the builting 'hourly', 'daily', and 'weekly' schedules
> in systemd. We can adjust the schedules such that:
>
>  1. Hourly runs avoid the 0th hour.
>  2. Daily runs avoid Monday.

Simple and stupid is good.  When I read the problem description, I
wondered if the hour in which daily jobs are run will also be
dispersed (so that the load of the server that helps daily tasks at
the clients will not be concentrated in a single hour out of 24
hours of a day), but hopefully the load is still spread within that
60 minutes evenly, which probably is good enough.

>
> This will keep maintenance runs from colliding when using systemd.
>
> Signed-off-by: Derrick Stolee <[email-masked]>
> ---
>  builtin/gc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/builtin/gc.c b/builtin/gc.c
> index e52129e485c..6f8df366fbe 100644
> --- a/builtin/gc.c
> +++ b/builtin/gc.c
> @@ -2350,11 +2350,11 @@ static int systemd_timer_write_timer_file(enum schedule_priority schedule,
>  
>  	switch (schedule) {
>  	case SCHEDULE_HOURLY:
> -		schedule_pattern = xstrfmt("*-*-* *:%02d:00", minute);
> +		schedule_pattern = xstrfmt("*-*-* 1..23:%02d:00", minute);
>  		break;
>  
>  	case SCHEDULE_DAILY:
> -		schedule_pattern = xstrfmt("*-*-* 0:%02d:00", minute);
> +		schedule_pattern = xstrfmt("Tue..Sun *-*-* 0:%02d:00", minute);
>  		break;
>  
>  	case SCHEDULE_WEEKLY: