Pin GALAXYSCOPE_MAX_WORKERS=1 in parallel scan tools (Fixes #4896)

tests/tools/cultural_gauntlet.py

@@ -454,6 +454,7 @@ def _run_cell(args: tuple[Any, ...]) -> dict[str, Any]:
     dbs = layers[1] if len(layers) > 1 else None  # part 3 (D): --db's {target: spec}
     os.environ.setdefault("GITGALAXY_LICENSE_KEY", "COMMUNITY_FREE_TIER")  # a pool process of its own
     os.environ["GITGALAXY_DISABLE_GIT_HISTORY"] = "1"
+    os.environ.setdefault("GALAXYSCOPE_MAX_WORKERS", "1")  # one scan per pool process: no pool inside (#4896)
     cell_dir = Path(work) / f"{dialect}__{column}"
     observe = _observe_collation if dialect in COLLATION_TARGETS else _observe_input if dialect in INPUT_FORMATS \
         else _observe  # fmt: skip

tests/tools/import_graph_accuracy.py

@@ -1310,6 +1310,7 @@ def scan_group(group_dir: Path, out_dir: Path) -> tuple[dict[str, str], set[tupl
     for one group, scanned in a subprocess pinned to THIS checkout (the console-script trap)."""
     env = {k: v for k, v in os.environ.items() if k != "PYTHONPATH"}
     env.update(PYTHONPATH=str(REPO_ROOT), GITGALAXY_DISABLE_GIT_HISTORY="1")
+    env.setdefault("GALAXYSCOPE_MAX_WORKERS", "1")  # scan_group runs --jobs at a time: no pool inside (#4896)
     out_dir.mkdir(parents=True, exist_ok=True)
     proc = subprocess.run(
         [sys.executable, "-c", _SCAN, str(REPO_ROOT), str(group_dir), str(out_dir / "g.json")],

tests/tools/test_unicode_gauntlet_scan_env.py

@@ -0,0 +1,45 @@
+"""The gauntlet runs --jobs scans at once, so each scan must stay single-worker (#4896, #3913)."""
+
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent))
+
+import unicode_gauntlet as ug  # noqa: E402
+
+
+def _scan_env(monkeypatch, tmp_path, preset=None):
+    import gitgalaxy.tools.cobol_to_cobol.galaxy_ir as ir
+
+    seen = {}
+
+    def fake(estate, out, extra_args=()):
+        import os
+
+        seen["workers"] = os.environ.get("GALAXYSCOPE_MAX_WORKERS")
+        return out
+
+    monkeypatch.setattr(ir, "scan_to_db", fake)
+    monkeypatch.delenv("GALAXYSCOPE_MAX_WORKERS", raising=False)
+    if preset:
+        monkeypatch.setenv("GALAXYSCOPE_MAX_WORKERS", preset)
+    ug.scan(tmp_path / "e__utf-8", tmp_path / "out")
+    return seen["workers"]
+
+
+def test_scan_env_pins_one_worker(monkeypatch, tmp_path):
+    assert _scan_env(monkeypatch, tmp_path) == "1"
+
+
+def test_scan_env_respects_explicit_value_and_restores(monkeypatch, tmp_path):
+    import os
+
+    assert _scan_env(monkeypatch, tmp_path, preset="3") == "3"
+    assert os.environ["GALAXYSCOPE_MAX_WORKERS"] == "3"
+
+
+def test_scan_env_does_not_leak(monkeypatch, tmp_path):
+    import os
+
+    _scan_env(monkeypatch, tmp_path)
+    assert "GALAXYSCOPE_MAX_WORKERS" not in os.environ

tests/tools/unicode_gauntlet.py

@@ -216,9 +216,12 @@ def scan(estate: Path, out: Path) -> Path:
 
     # set for the scan only: a process-wide GITGALAXY_DISABLE_GIT_HISTORY outlives it and silently
     # turns git off for every later test in a pytest session (it once broke test_chronometer)
-    keys = ("GITGALAXY_LICENSE_KEY", "GITGALAXY_DISABLE_GIT_HISTORY")
+    keys = ("GITGALAXY_LICENSE_KEY", "GITGALAXY_DISABLE_GIT_HISTORY", "GALAXYSCOPE_MAX_WORKERS")
     saved = {k: os.environ.get(k) for k in keys}
     os.environ.setdefault("GITGALAXY_LICENSE_KEY", "COMMUNITY_FREE_TIER")
+    # --jobs scans already fill the box: a worker pool inside each one is N x N processes (#4896,
+    # #3913). An explicit value from the caller wins.
+    os.environ.setdefault("GALAXYSCOPE_MAX_WORKERS", "1")
     os.environ["GITGALAXY_DISABLE_GIT_HISTORY"] = "1"
     codec = estate.name.rpartition("__")[2]
     try: