Re: RFC: Would a config fetch.retryCount make sense?

From: Stefan Beller <sbeller@google.com>
Date: Jun 1, 2017, 17:59 UTC
Message-ID: <CAGZ79kZiPgsFaj23QvtgEgUhMiA5ygowY4OorSnzEfCdbv=a7g@mail.gmail.com>
In-Reply-To: <6762A30E-C558-4085-943B-AB85EBF18706@gmail.com>

On Thu, Jun 1, 2017 at 5:48 AM, Lars Schneider <larsxschneider@gmail.com> wrote:

Show 5 quoted lines

> Hi,
>
> we occasionally see "The remote end hung up unexpectedly" (pkt-line.c:265)
> on our `git fetch` calls (most noticeably in our automations). I expect
> random network glitches to be the cause.

There is 665b35eccd (submodule--helper: initial clone learns retry logic, 2016-06-09) but that is for submodules and only the initial clone.

I tried searching the mailing list archive if it was discussed for fetch before (I am sure it was), but could not find a good hint to link at.

IIRC one major concern was:
* When a human operates git-fetch, then they want to have fast feedback.
  The failure may be non-transient, for example when I forgot to up the
  wifi connection. Then the human can inspect and fix the root cause.
  (Assumption in human workflow: these non transient errors happen more
  often than the occasional fetch error due to network glitches.)

For automation I would expect that the retry logic is actually beneficial, such that you would want to have a command line options such as "git fetch --retries=5 --delay-between-retries=10s".

>
> In some places we added a basic retry mechanism and I was wondering
> if this could be a useful feature for Git itself.

There are already retries in other places. :) Cf. f4ab4f3ab1 (lock_packed_refs(): allow retries when acquiring the packed-refs lock, 2015-05-11), which solves the need of github on the serverside, when they have a very active repo that multiple people push to at the same time. (to different branches. I believe that forks are internally handled as the same repo, just with different namespaces. So if there are 1000 forks of linux.git you see a lot of pushes to the "same" repo)

>
> E.g. a Git config such as "fetch.retryCount" or something.
> Or is there something like this in Git already and I missed it?

I like it.

Thanks, Stefan