comparison tests/test-simple-update.t @ 38731:ef3838a47503

worker: ability to disable thread unsafe tasks

The worker on Windows is implemented using a thread pool. If worker
tasks are not thread safe, badness can occur. In addition, if tasks
are executing CPU bound code and holding onto the GIL, there will be
non-substantial overhead in Python context switching between active
threads. This can result in significant slowdowns of tasks.

This commit teaches the code for determining whether to use a worker
to take thread safety into account. Effectively, thread unsafe tasks
don't use the thread-based worker on Windows.

Differential Revision: https://phab.mercurial-scm.org/D3962

38730:69ed2cff4277

#if no-windows

  $ cat <<EOF > forceworker.py
  > from mercurial import extensions, worker
  > def nocost(orig, ui, costperop, nops):
  >     return worker._numworkers(ui) > 1
  > def uisetup(ui):
  >     extensions.wrapfunction(worker, 'worthwhile', nocost)
  > EOF

38731:ef3838a47503

#if no-windows

  $ cat <<EOF > forceworker.py
  > from mercurial import extensions, worker
  > def nocost(orig, ui, costperop, nops, threadsafe=True):
  >     return worker._numworkers(ui) > 1
  > def uisetup(ui):
  >     extensions.wrapfunction(worker, 'worthwhile', nocost)
  > EOF