Use execnet main_thread_only execmodel

Use the execnet main_thread_only execmodel so that code which expects
to run in the main thread will just work.  This execmodel has been
merged to the execnet master branch via pytest-dev/execnet#243, so this
patch should not be merged until there is a released version of execnet
supporting the main_thread_only execmodel.

Also increase minimum python version to 3.8 since execnet dropped 3.7
support in pytest-dev/execnet#245.

Closes: #620

Author: zmedico

.github/workflows/test.yml

@@ -34,7 +34,6 @@ jobs:
       fail-fast: false
       matrix:
         tox_env:
-          - "py37-pytestlatest"
           - "py38-pytestlatest"
           - "py39-pytestlatest"
           - "py310-pytestlatest"
@@ -46,8 +45,6 @@ jobs:
 
         os: [ubuntu-latest, windows-latest]
         include:
-          - tox_env: "py37-pytestlatest"
-            python: "3.7"
           - tox_env: "py38-pytestlatest"
             python: "3.8"
           - tox_env: "py39-pytestlatest"

changelog/620.bugfix

@@ -0,0 +1,3 @@
+Use the execnet main_thread_only execmodel so that code which expects to run in the main thread will just work.
+
+Also increase minimum python version to 3.8 since execnet dropped 3.7 support in pytest-dev/execnet#245.

pyproject.toml

@@ -25,16 +25,15 @@ classifiers = [
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
     "Programming Language :: Python :: 3 :: Only",
-    "Programming Language :: Python :: 3.7",
     "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
 ]
-requires-python = ">=3.7"
+requires-python = ">=3.8"
 dependencies = [
-    "execnet>=1.1",
+    "execnet@git+https://github.com/pytest-dev/execnet#egg=master",
     "pytest>=6.2.0",
 ]
 dynamic = ["version"]

src/xdist/looponfail.py

@@ -76,7 +76,7 @@ def trace(self, *args):
             print("RemoteControl:", msg)
 
     def initgateway(self):
-        return execnet.makegateway("popen")
+        return execnet.makegateway("execmodel=main_thread_only//popen")
 
     def setup(self, out=None):
         if out is None:

src/xdist/workermanage.py

@@ -41,13 +41,15 @@ def __init__(self, config, specs=None, defaultchdir="pyexecnetcache") -> None:
         self.testrunuid = self.config.getoption("testrunuid")
         if self.testrunuid is None:
             self.testrunuid = uuid.uuid4().hex
-        self.group = execnet.Group()
+        self.group = execnet.Group(execmodel="main_thread_only")
         if specs is None:
             specs = self._getxspecs()
         self.specs = []
         for spec in specs:
             if not isinstance(spec, execnet.XSpec):
                 spec = execnet.XSpec(spec)
+            if getattr(spec, "execmodel", None) != "main_thread_only":
+                spec = execnet.XSpec(f"execmodel=main_thread_only//{spec}")
             if not spec.chdir and not spec.popen:
                 spec.chdir = defaultchdir
             self.group.allocate_id(spec)
@@ -68,6 +70,10 @@ def setup_nodes(self, putevent):
         return [self.setup_node(spec, putevent) for spec in self.specs]
 
     def setup_node(self, spec, putevent):
+        if not isinstance(spec, execnet.XSpec):
+            spec = execnet.XSpec(spec)
+        if getattr(spec, "execmodel", None) != "main_thread_only":
+            spec = execnet.XSpec(f"execmodel=main_thread_only//{spec}")
         gw = self.group.makegateway(spec)
         self.config.hook.pytest_xdist_newgateway(gateway=gw)
         self.rsync_roots(gw)

testing/test_remote.py

@@ -38,7 +38,7 @@ def __init__(self, request, pytester: pytest.Pytester) -> None:
     def setup(self) -> None:
         self.pytester.chdir()
         # import os ; os.environ['EXECNET_DEBUG'] = "2"
-        self.gateway = execnet.makegateway()
+        self.gateway = execnet.makegateway("execmodel=main_thread_only//popen")
         self.config = config = self.pytester.parseconfigure()
         putevent = self.events.put if self.use_callback else None
 

testing/test_workermanage.py

@@ -72,7 +72,7 @@ def test_popen_makegateway_events(
         assert len(call.specs) == 2
 
         call = hookrecorder.popcall("pytest_xdist_newgateway")
-        assert call.gateway.spec == execnet.XSpec("popen")
+        assert call.gateway.spec == execnet.XSpec("execmodel=main_thread_only//popen")
         assert call.gateway.id == "gw0"
         call = hookrecorder.popcall("pytest_xdist_newgateway")
         assert call.gateway.id == "gw1"
@@ -162,7 +162,7 @@ def test_hrsync_filter(self, source: Path, dest: Path) -> None:
         assert names == {"dir", "file.txt", "somedir"}
 
     def test_hrsync_one_host(self, source: Path, dest: Path) -> None:
-        gw = execnet.makegateway("popen//chdir=%s" % dest)
+        gw = execnet.makegateway("execmodel=main_thread_only//popen//chdir=%s" % dest)
         finished = []
         rsync = HostRSync(source)
         rsync.add_target_host(gw, finished=lambda: finished.append(1))

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 envlist=
   linting
-  py{37,38,39,310,311,312}-pytestlatest
+  py{38,39,310,311,312}-pytestlatest
   py310-pytestmain
   py310-psutil
   py310-setproctitle