Hello,
I would like to propose a change in our build to help us improve developer
efficiency.
The proposal is to support separate compilation of unit tests.
Currently, we have the old approach of invoking `make check -j N
GTEST_FILTER=""`, or a newer option of doing `make tests -j N`. From what
I've heard the latter is slightly faster. However, when someone is
developing a specific feature, it's likely that they would like to make
changes and iterate on a single test file. In this workflow, having to
compile (virtually) __all__ of the tests is very burdensome. This situation
is not so bad if you're working in a very isolated part of the codebase,
but it gets to be pretty bad if you're experimenting with parts that are
widely used.
An example of a workflow I'm aiming for would look something like:
1. write some code...
2. `make check master_tests` // compile and test
`src/tests/master_tests.cpp`
3. fix compilation errors...
4. `make check master_tests` // compile and test
`src/tests/master_tests.cpp`
5. change some stuff...
6. `make check master_tests` // compile and test
`src/tests/master_tests.cpp`
7. debug...
8. `make check master_tests` // compile and test
`src/tests/master_tests.cpp`
9. alright, looks good. `make check`
I have 0 attachment to the `make check master_tests` syntax. It'll be a
different syntax for CMake anyways. I just think that the ability to
perform separate compilation of tests will be immensely useful.
Some numbers to justify what I'm proposing:
- `make -j 8` on my laptop takes roughly 10 mins.
- `make tests -j 8` takes about 30 mins.
Of course, not every change you make triggers all of the tests to
recompile. But if you change components that are widely used, it does end
up recompiling virtually everything. Under these circumstances, I would
love for each iteration to be 11 mins (10 mins + __at most__ 1 min to
compile the single test), rather than 30 mins.
NOTE: My laptop is expensive... some people even use machines with 64 cores
or whatever to compile Mesos. Not everyone has access to this kind of
equipment. We should strive for something better than "throw more money at
it".
The goal of this thread for me is the following:
(1) Capture whether this is something most people experience, or whether
I'm just doing it wrong
(2) If most people do experience this inefficiency and would like this
change to be made,
I would like to recruit 1 or 2 people to help me deliver this, since
I'm not a automake nor CMake expert.
