Parallel node setup v2

src/xdist/scheduler/loadscope.py

@@ -162,6 +162,9 @@ def add_node(self, node: WorkerController) -> None:
         """
         assert node not in self.assigned_work
         self.assigned_work[node] = {}
+        self.assigned_work = dict(
+            sorted(self.assigned_work.items(), key=lambda item: item[0].gateway.id)
+        )
 
     def remove_node(self, node: WorkerController) -> str | None:
         """Remove a node from the scheduler.

src/xdist/workermanage.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from collections.abc import Sequence
+from concurrent.futures import ThreadPoolExecutor
 import enum
 import fnmatch
 import os
@@ -92,9 +93,17 @@ def setup_nodes(
         self,
         putevent: Callable[[tuple[str, dict[str, Any]]], None],
     ) -> list[WorkerController]:
+        # create basetemp directory only once
+        if hasattr(self.config, "_tmp_path_factory"):
+            self.config._tmp_path_factory.getbasetemp()
+
         self.config.hook.pytest_xdist_setupnodes(config=self.config, specs=self.specs)
         self.trace("setting up nodes")
-        return [self.setup_node(spec, putevent) for spec in self.specs]
+        with ThreadPoolExecutor(max_workers=len(self.specs)) as executor:
+            futs = [
+                executor.submit(self.setup_node, spec, putevent) for spec in self.specs
+            ]
+            return [f.result() for f in futs]
 
     def setup_node(
         self,

testing/test_workermanage.py

@@ -82,11 +82,15 @@ def test_popen_makegateway_events(
         call = hookrecorder.popcall("pytest_xdist_setupnodes")
         assert len(call.specs) == 2
 
-        call = hookrecorder.popcall("pytest_xdist_newgateway")
-        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"
+        # check expected gateways
+        gw_calls = [
+            hookrecorder.popcall("pytest_xdist_newgateway"),
+            hookrecorder.popcall("pytest_xdist_newgateway"),
+        ]
+        assert {c.gateway.id for c in gw_calls} == {"gw0", "gw1"}
+        assert {c.gateway.spec for c in gw_calls} == {
+            execnet.XSpec("execmodel=main_thread_only//popen")
+        }
         assert len(hm.group) == 2
         hm.teardown_nodes()
         assert not len(hm.group)