[all-commits] [llvm/llvm-project] 0e13a0: [llvm-cov] Prevent llvm-cov from using too many th...

[Alexandre Ganea via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 0e13a0331fb90078bf71cc0c4612492a6954a5d0
      https://github.com/llvm/llvm-project/commit/0e13a0331fb90078bf71cc0c4612492a6954a5d0
  Author: Alexandre Ganea <alexandre.ganea at ubisoft.com>
  Date:   2020-04-24 (Fri, 24 Apr 2020)

  Changed paths:
    M llvm/include/llvm/Support/Threading.h
    M llvm/lib/Support/Threading.cpp
    M llvm/tools/dsymutil/dsymutil.cpp
    M llvm/tools/llvm-cov/CodeCoverage.cpp
    M llvm/tools/llvm-cov/CoverageExporterJson.cpp
    M llvm/tools/llvm-cov/CoverageReport.cpp

  Log Message:
  -----------
  [llvm-cov] Prevent llvm-cov from using too many threads

As reported here: https://reviews.llvm.org/D75153#1987272

Before, each instance of llvm-cov was creating one thread per hardware core, which wasn't needed probably because the number of inputs were small. This was probably causing a thread rlimit issue on large core count systems.

After this patch, the previous behavior is restored (to what was before rG8404aeb5):

If --num-threads is not specified, we create one thread per input, up to num.cores.
When specified, --num-threads indicates any number of threads, with no upper limit.

Differential Revision: https://reviews.llvm.org/D78408