Disable tensoradapter and "using backend: xxx" log by default (#3684)

* fix

* lint

* lint

* address comment

docs/source/env_var.rst

@@ -7,6 +7,10 @@ Global Configurations
     * Values: String (default=``"${HOME}/.dgl"``)
     * The directory to save the DGL configuration files.
 
+* ``DGL_LOG_DEBUG``:
+    * Values: Set to ``"1"`` to enable debug level logging for DGL
+    * Enable debug level logging for DGL
+
 Backend Options
 ---------------
 * ``DGLBACKEND``:

python/dgl/__init__.py

@@ -9,6 +9,9 @@ and transforming graphs.
 # This initializes Winsock and performs cleanup at termination as required
 import socket
 
+# setup logging before everything
+from .logging import enable_verbose_logging
+
 # Should import backend before importing anything else
 from .backend import load_backend, backend_name
 

python/dgl/_ffi/base.py

@@ -6,6 +6,7 @@ from __future__ import absolute_import
 import sys
 import os
 import ctypes
+import logging
 import numpy as np
 from . import libinfo
 
@@ -136,3 +137,6 @@ def load_tensor_adapter(backend, version):
         raise NotImplementedError('Unsupported system: %s' % sys.platform)
     path = os.path.join(_DIR_NAME, 'tensoradapter', backend, basename)
     tensor_adapter_loaded = (_LIB.DGLLoadTensorAdapter(path.encode('utf-8')) == 0)
+    if not tensor_adapter_loaded:
+        logger = logging.getLogger("dgl-core")
+        logger.warning("Memory optimization with PyTorch is not enabled.")

python/dgl/backend/__init__.py

@@ -4,12 +4,14 @@ import sys
 import os
 import json
 import importlib
+import logging
 
 from . import backend
 from .set_default_backend import set_default_backend
 
 _enabled_apis = set()
 
+logger = logging.getLogger("dgl-core")
 
 def _gen_missing_api(api, mod_name):
     def _missing_api(*args, **kwargs):
@@ -42,7 +44,7 @@ def load_backend(mod_name):
     version = mod.__version__
     load_tensor_adapter(mod_name, version)
 
-    print('Using backend: %s' % mod_name, file=sys.stderr)
+    logger.debug('Using backend: %s' % mod_name)
     mod = importlib.import_module('.%s' % mod_name, __name__)
     thismod = sys.modules[__name__]
     for api in backend.__dict__.keys():

python/dgl/logging.py

+"""logging module for DGL"""
+import logging
+import os
+
+
+def enable_verbose_logging():
+    """
+    Enable debug level logging for DGL
+    """
+    os.environ["DMLC_LOG_DEBUG"] = "1"
+    logger = logging.getLogger("dgl-core")
+    logger.setLevel(logging.DEBUG)
+    logging.info("DGL's logging level is set to DEBUG")
+
+
+def _setup_logger():
+    """setup logger"""
+    logger = logging.getLogger("dgl-core")
+    console = logging.StreamHandler()
+    formatter = logging.Formatter(
+        "%(asctime)s %(filename)s:%(lineno)s %(levelname)s p:%(processName)s \
+        t:%(threadName)s: %(message)s"
+    )
+    console.setFormatter(formatter)
+    console.setLevel(logging.DEBUG)
+    logger.addHandler(console)
+    logger.propagate = False
+    logger.setLevel(logging.INFO)
+
+
+_setup_logger()
+
+if os.environ.get("DGL_LOG_DEBUG", None) == "1":
+    enable_verbose_logging()