initialization in first use

python/pyarrow/_s3.pyx

@@ -47,6 +47,16 @@ def finalize_s3():
     check_status(CFinalizeS3())
 
 
+cdef bint _initialized = False
+
+
+cdef _ensure_initialized():
+    global _initialized
+    if not _initialized:
+        initialize_s3()
+        _initialized = True
+
+
 cdef class S3FileSystem(FileSystem):
     """S3-backed FileSystem implementation
 
@@ -79,9 +89,12 @@ cdef class S3FileSystem(FileSystem):
                  scheme='https', endpoint_override=None,
                  bint background_writes=True):
         cdef:
-            CS3Options options = CS3Options.Defaults()
+            CS3Options options
             shared_ptr[CS3FileSystem] wrapped
 
+        _ensure_initialized()
+
+        options = CS3Options.Defaults()
         if access_key is not None or secret_key is not None:
             options.ConfigureAccessKey(tobytes(access_key),
                                        tobytes(secret_key))

python/pyarrow/fs.py

@@ -30,5 +30,3 @@
     from pyarrow._s3 import S3FileSystem, initialize_s3, finalize_s3  # noqa
 except ImportError:
     pass
-else:
-    initialize_s3()

python/pyarrow/tests/conftest.py

@@ -274,22 +274,3 @@ def minio_server():
         finally:
             if proc is not None:
                 proc.kill()
-
-
-@pytest.fixture(scope='session')
-def minio_client(minio_server):
-    minio = pytest.importorskip('minio')
-    address, access_key, secret_key = minio_server
-    return minio.Minio(
-        address,
-        access_key=access_key,
-        secret_key=secret_key,
-        secure=False
-    )
-
-
-@pytest.fixture(scope='session')
-def minio_bucket(minio_client):
-    bucket_name = 'pyarrow-bucket'
-    minio_client.make_bucket(bucket_name)
-    return bucket_name

python/pyarrow/tests/test_fs.py

@@ -54,7 +54,6 @@ def subtree_localfs(request, tempdir, localfs):
 @pytest.fixture
 def s3fs(request, minio_server):
     from pyarrow.fs import S3FileSystem
-    # initialize_s3()
 
     address, access_key, secret_key = minio_server
     bucket = 'pyarrow-filesystem/'