[PATCH] Teach CMake build system to run lit's own test suite

[Dan Liew via llvm-commits]

Hi JF,

On 9 January 2016 at 01:16, JF Bastien <jfb at chromium.org> wrote:
> Hi Dan,
>
> I don't know if I'm the only one getting this, but it seems like your patch
> causes timeouts for me and for some bots I'm testing with (they're all
> timing out after your commit).

What is your timeout for your bots? If your system has the Python
psutil module installed the lit timeout tests will run which are a
little slow but **should not** hang indefinitely.

```
$ time ninja check-lit
[2/2] Running lit's tests
lit.py: lit.cfg:58: note: Found python psutil module
Testing Time: 16.90s
  Expected Passes    : 14

real    0m17.096s
user    0m13.610s
sys     0m0.577s
```



> I used the following to repro locally:
>
> cmake ../llvm -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DLLVM_BUILD_TESTS=ON
> -DCMAKE_BUILD_TYPE=RelWithDebInfo -DLLVM_ENABLE_ASSERTIONS=ON
> -DLLVM_TARGETS_TO_BUILD="X86" && make check-all -j$(nproc)
>
> Things are stuck at "running all regression tests".
>
> I have the python processes at the bottom of this email hung (all disappear
> when I kill make). I'm pretty suspicious of the infinite_loop.py test
> considering things seem to loop forever :-)

That test is deliberately running a program that loops forever to test
that the ``--timeout=`` feature of lit works. If it hangs it likely
means there is a bug with that feature.

> The LLVM waterfall at http://lab.llvm.org:8011/console seems fine, so maybe
> it's a Python version difference? The bots I'm using are pretty simple x86
> machines, whereas my machine is a beefy one, so I don't think it's a problem
> with too-slow or too-big machine.

When I wrote the ``--timeout=`` tests I tested Python 2.7 and Python
3.4 with the version 3.2 of the Python psutil module

Could you tell me

- What OS you are using (e.g. Ubuntu 14.04LTS)
- What Python version you have
- What version of the Python psutil module you have

With that I can have a go at reproducing your issue.

> Would you have an idea of what's going on? I haven't dug into the code yet
> since I figure you may already have a hunch.

My hunch is that if you have an old version of psutil installed it
might be behaving badly and failing to kill the processes (see
``killProcessAndChildren()`` in ``utils/lit/lit/util.py``).
If that is the case this might accelerate my plans to remove the
dependency on the psutil module.

Note I'm seeing Windows buildbot failures (not related to lit timeout feature)

http://lab.llvm.org:8011/builders/clang-x64-ninja-win7/builds/8760
http://lab.llvm.org:8011/builders/clang-x86-win2008-selfhost/builds/5613

so I need to revert my commit until I can work out why the tests are
broken under Windows (eurgh...)

Unfortunately it seems svn is down right now so I can't do anything
until it's back up.

Dan.