Declare the extension as parallel safe

Closes #222

CHANGELOG.rst

@@ -6,6 +6,11 @@ Versions follow `Semantic Versioning <https://semver.org/>`_ (``<major>.<minor>.
 TBC (TBC)
 ---------
 
+Features
+^^^^^^^^
+* `#222 <https://github.com/readthedocs/sphinx-autoapi/issues/222>`:
+  Declare the extension as parallel safe.
+
 Bug Fixes
 ^^^^^^^^^
 * `#219 <https://github.com/readthedocs/sphinx-autoapi/issues/219>`:

autoapi/extension.py

@@ -316,3 +316,8 @@ def setup(app):
     app.add_event("autoapi-skip-member")
     app.setup_extension("sphinx.ext.inheritance_diagram")
     app.add_directive("autoapi-inheritance-diagram", AutoapiInheritanceDiagram)
+
+    return {
+        "parallel_read_safe": True,
+        "parallel_write_safe": True,
+    }

tests/python/test_pyintegration.py

@@ -23,7 +23,7 @@ from autoapi.mappers.python import (
 def builder():
     cwd = os.getcwd()
 
-    def build(test_dir, confoverrides=None):
+    def build(test_dir, confoverrides=None, **kwargs):
         os.chdir("tests/python/{0}".format(test_dir))
         app = Sphinx(
             srcdir=".",
@@ -32,6 +32,7 @@ def builder():
             doctreedir="_build/.doctrees",
             buildername="text",
             confoverrides=confoverrides,
+            **kwargs
         )
         app.build(force_all=True)
 
@@ -639,6 +640,12 @@ class TestComplexPackage(object):
         assert "unicode_str" in foo_file
 
 
+class TestComplexPackageParallel(object):
+    @pytest.fixture(autouse=True, scope="class")
+    def built(self, builder):
+        builder("pypackagecomplex", parallel=2)
+
+
 @pytest.mark.skipif(
     sys.version_info < (3, 3), reason="Implicit namespace not supported in python < 3.3"
 )