Re: Git Test Coverage Report (v2.20.0-rc0)

From: Ben Peart <peartben@gmail.com>
To: "Derrick Stolee" <stolee@gmail.com>,
	"git@vger.kernel.org" <git@vger.kernel.org>,
	"Jeff King" <peff@peff.net>, "Stefan Beller" <sbeller@google.com>,
	"Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>,
	"Ben Peart" <benpeart@microsoft.com>
Subject: Re: Git Test Coverage Report (v2.20.0-rc0)
Date: Mon, 19 Nov 2018 14:00:27 -0500	[thread overview]
Message-ID: <d39320e2-0614-569b-4e82-7f7541589aea@gmail.com> (raw)
In-Reply-To: <6f532502-d4b6-17f6-0ec7-01079077ac90@gmail.com>

On 11/19/2018 10:40 AM, Derrick Stolee wrote:
> The test coverage reports started mid-way through this release cycle, so 
> I thought it would be good to do a full review of the new uncovered code 
> since the last release.
> 
> I eliminated most of the uncovered code due to the following cases:
> 
> 1. Code was only moved or refactored.
> 2. Code was related to unusual error conditions (e.g. open_pack_index() 
> fails)
> 
> The comments below are intended only to point out potential directions 
> to improve test coverage. Some of it is for me to do!
> 
> Thanks,
> -Stolee
> 
> On 11/18/2018 9:54 PM, Derrick Stolee wrote:
> 
> There are a lot of lines introduced by the IEOT extension in these commits:
> 
>  > Ben Peart      3255089ad: ieot: add Index Entry Offset Table (IEOT) 
> extension
>  > Ben Peart      3b1d9e045: eoie: add End of Index Entry (EOIE) extension
>  > Ben Peart      77ff1127a: read-cache: load cache entries on worker 
> threads
>  > Ben Peart      abb4bb838: read-cache: load cache extensions on a 
> worker thread
>  > Ben Peart      c780b9cfe: config: add new index.threads config setting
>  > Ben Peart      d1664e73a: add: speed up cmd_add() by utilizing 
> read_cache_preload()
>  > Ben Peart      fa655d841: checkout: optimize "git checkout -b 
> <new_branch>"
> 

These should be hit if you run the test suite with 
GIT_TEST_INDEX_THREADS=2.  Without that, the indexes for the various 
tests are too small to trigger multi-threaded index reads/writes.

 From t/README:

GIT_TEST_INDEX_THREADS=<n> enables exercising the multi-threaded loading
of the index for the whole test suite by bypassing the default number of
cache entries and thread minimums. Setting this to 1 will make the
index loading single threaded.