[all-commits] [llvm/llvm-project] 9a26d2: [clangd][unittests] Limit paralelism for clangd un...

[kadir çetinkaya via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9a26d2c6d35f574d7a4b06a5a22f8a1c063cb664
      https://github.com/llvm/llvm-project/commit/9a26d2c6d35f574d7a4b06a5a22f8a1c063cb664
  Author: Kadir Cetinkaya <kadircet at google.com>
  Date:   2023-09-06 (Wed, 06 Sep 2023)

  Changed paths:
    M clang-tools-extra/clangd/unittests/lit.cfg.py

  Log Message:
  -----------
  [clangd][unittests] Limit paralelism for clangd unittests

We started seeing a lot of timeouts that align with the change in lit to
execute gtests in shards. The logic there assumes tests are
single-threaded, which is the case for most of the LLVM, hence they
pick #shards ~ #cores (by slightly overshooting).

There are enough unittests in clangd that rely on multi-threading, they
can create arbitrarily many threads but we limit amount of meaningful
work to ~4 thread per process.

This change ensures that we're accounting for that paralelism when
executing clangd tests and not overloading test executors.

In theory the change overestimates the requirements, not all tests are
multi-threaded, but it doesn't seem to be resulting in any regressions
on my local runs.

Fixes https://github.com/llvm/llvm-project/issues/64964.
Fixes https://github.com/clangd/clangd/issues/1712.