Perf: lazy imports, lighter stdlib, parallel session loading, lazy LRO progress bar

Category 1 - Core lazy import deferral (~40-50ms saving):
  - Defer yaml, base64, binascii, getpass, ssl, urlopen in core/util.py
  - Defer humanfriendly.terminal.spinners.Spinner in commands/progress.py
  - Defer concurrent.futures/ThreadPoolExecutor in core/__init__.py
  - Defer pkginfo in extension/__init__.py
  - Defer urlparse in extension/operations.py
  - Defer hashlib in decorators.py
  - Defer shutil in local_context.py
  - Defer random in commands/validators.py
  - Defer yaml, use importlib.resources in _help_loaders.py
  - Defer AAZLROPoller in aaz/_command.py
  - Defer AAZNoPolling/AAZBasePolling in aaz/_client.py

Category 2 - Lighter stdlib replacements (~5-10ms saving):
  - Replace timeit.default_timer() with time.perf_counter()
  - Replace platform.system() with sys.platform in parameters.py
  - Cache platform.uname() in telemetry.py _get_base_properties()

Category 7 - Telemetry lazy imports (~10-15ms saving):
  - Defer subprocess, portalocker in telemetry/__init__.py
  - Defer urllib.request, urllib.error in telemetry_client.py
  - Defer logging.handlers in telemetry/util.py

Category 12 - Parallel session file loading (~70-75ms saving):
  - Load session files via ThreadPoolExecutor in AzCli.__init__

Category 14 - Lazy LongRunningOperation progress bar (~66ms saving):
  - Make progress_bar a lazy @Property in LongRunningOperation
  - Defer IndeterminateProgressBar import to first access

Also fix: call_once decorator was not setting executed=True flag.

Author: ReaNAiveD

src/azure-cli-core/azure/cli/core/__init__.py

@@ -9,9 +9,7 @@
 import os
 import sys
 import json
-import timeit
-import concurrent.futures
-from concurrent.futures import ThreadPoolExecutor
+import time
 
 from knack.cli import CLI
 from knack.commands import CLICommandsLoader
@@ -100,14 +98,24 @@ def __init__(self, **kwargs):
 
         azure_folder = self.config.config_dir
         ensure_dir(azure_folder)
-        ACCOUNT.load(os.path.join(azure_folder, 'azureProfile.json'))
-        CONFIG.load(os.path.join(azure_folder, 'az.json'))
-        SESSION.load(os.path.join(azure_folder, 'az.sess'), max_age=3600)
-        INDEX.load(os.path.join(azure_folder, 'commandIndex.json'))
-        EXTENSION_INDEX.load(os.path.join(azure_folder, 'extensionIndex.json'))
-        HELP_INDEX.load(os.path.join(azure_folder, 'helpIndex.json'))
-        EXTENSION_HELP_INDEX.load(os.path.join(azure_folder, 'extensionHelpIndex.json'))
-        VERSIONS.load(os.path.join(azure_folder, 'versionCheck.json'))
+
+        # Load session files in parallel — each open() costs ~20ms on Windows due to
+        # filesystem/antivirus overhead, and file I/O releases the GIL.
+        from concurrent.futures import ThreadPoolExecutor
+        load_tasks = [
+            (ACCOUNT, os.path.join(azure_folder, 'azureProfile.json'), 0),
+            (CONFIG, os.path.join(azure_folder, 'az.json'), 0),
+            (SESSION, os.path.join(azure_folder, 'az.sess'), 3600),
+            (INDEX, os.path.join(azure_folder, 'commandIndex.json'), 0),
+            (EXTENSION_INDEX, os.path.join(azure_folder, 'extensionIndex.json'), 0),
+            (HELP_INDEX, os.path.join(azure_folder, 'helpIndex.json'), 0),
+            (EXTENSION_HELP_INDEX, os.path.join(azure_folder, 'extensionHelpIndex.json'), 0),
+            (VERSIONS, os.path.join(azure_folder, 'versionCheck.json'), 0),
+        ]
+        with ThreadPoolExecutor(max_workers=len(load_tasks)) as pool:
+            futures = [pool.submit(s.load, path, max_age=age) for s, path, age in load_tasks]
+            for f in futures:
+                f.result()
         handle_version_update()
 
         self.cloud = get_active_cloud(self)
@@ -322,14 +330,14 @@ def _update_command_table_from_modules(args, command_modules=None):
                 except ImportError as e:
                     logger.warning(e)
 
-            start_time = timeit.default_timer()
+            start_time = time.perf_counter()
             logger.debug("Loading command modules...")
             results = self._load_modules(args, command_modules)
 
             count, cumulative_group_count, cumulative_command_count = \
                 self._process_results_with_timing(results)
 
-            total_elapsed_time = timeit.default_timer() - start_time
+            total_elapsed_time = time.perf_counter() - start_time
             # Summary line
             logger.debug(self.item_format_string,
                          "Total ({})".format(count), total_elapsed_time,
@@ -404,7 +412,7 @@ def _filter_modname(extensions):
                     # Add to the map. This needs to happen before we load commands as registering a command
                     # from an extension requires this map to be up-to-date.
                     # self._mod_to_ext_map[ext_mod] = ext_name
-                    start_time = timeit.default_timer()
+                    start_time = time.perf_counter()
                     extension_command_table, extension_group_table, extension_command_loader = \
                         _load_extension_command_loader(self, args, ext_mod)
                     import_extension_breaking_changes(ext_mod)
@@ -427,7 +435,7 @@ def _filter_modname(extensions):
                     self.command_table.update(extension_command_table)
                     self.command_group_table.update(extension_group_table)
 
-                    elapsed_time = timeit.default_timer() - start_time
+                    elapsed_time = time.perf_counter() - start_time
                     logger.debug(self.item_ext_format_string, ext_name, elapsed_time,
                                  len(extension_group_table), len(extension_command_table),
                                  ext_dir)
@@ -667,6 +675,8 @@ def load_arguments(self, command=None):
 
     def _load_modules(self, args, command_modules):
         """Load command modules using ThreadPoolExecutor with timeout protection."""
+        import concurrent.futures
+        from concurrent.futures import ThreadPoolExecutor
         from azure.cli.core.commands import BLOCKED_MODS
 
         results = []
@@ -708,10 +718,10 @@ def _load_single_module(self, mod, args):
         from azure.cli.core.commands import _load_module_command_loader
         import traceback
         try:
-            start_time = timeit.default_timer()
+            start_time = time.perf_counter()
             module_command_table, module_group_table, command_loader = _load_module_command_loader(self, args, mod)
             import_module_breaking_changes(mod)
-            elapsed_time = timeit.default_timer() - start_time
+            elapsed_time = time.perf_counter() - start_time
             return ModuleLoadResult(mod, module_command_table, module_group_table, elapsed_time, command_loader=command_loader)
         except Exception as ex:  # pylint: disable=broad-except
             tb_str = traceback.format_exc()
@@ -1227,7 +1237,7 @@ def update(self, command_table):
 
         :param command_table: The command table built by azure.cli.core.MainCommandsLoader.load_command_table
         """
-        start_time = timeit.default_timer()
+        start_time = time.perf_counter()
         self.INDEX[self._COMMAND_INDEX_VERSION] = __version__
         self.INDEX[self._COMMAND_INDEX_CLOUD_PROFILE] = self.cloud_profile
         from collections import defaultdict
@@ -1242,7 +1252,7 @@ def update(self, command_table):
             if module_name not in index[top_command]:
                 index[top_command].append(module_name)
 
-        elapsed_time = timeit.default_timer() - start_time
+        elapsed_time = time.perf_counter() - start_time
         self.INDEX[self._COMMAND_INDEX] = index
 
         self.update_extension_index(command_table)

src/azure-cli-core/azure/cli/core/_help_loaders.py

@@ -11,8 +11,6 @@
 from knack.util import CLIError
 from knack.log import get_logger
 
-import yaml
-
 logger = get_logger(__name__)
 
 try:
@@ -100,7 +98,12 @@ class YamlLoaderMixin:  # pylint:disable=too-few-public-methods
     # get the list of yaml help file names for the command or group
     @staticmethod
     def _get_yaml_help_files_list(nouns, cmd_loader_map_ref):
-        import inspect
+        """Get list of YAML help file paths for the command or group.
+
+        Uses importlib.resources for zip-compatible package file discovery,
+        with a fallback to filesystem-based os.listdir for older layouts.
+        """
+        import importlib.resources
 
         command_nouns = " ".join(nouns)
         # if command in map, get the loader. Path of loader is path of helpfile.
@@ -121,17 +124,19 @@ def _get_yaml_help_files_list(nouns, cmd_loader_map_ref):
         results = []
         if loaders:
             for loader in loaders:
-                loader_file_path = inspect.getfile(loader.__class__)
-                dir_name = os.path.dirname(loader_file_path)
-                files = os.listdir(dir_name)
-                for file in files:
-                    if file.endswith("help.yaml") or file.endswith("help.yml"):
-                        help_file_path = os.path.join(dir_name, file)
-                        results.append(help_file_path)
+                # Use importlib.resources for zip-compatible package file discovery
+                loader_module = loader.__class__.__module__
+                pkg_files = importlib.resources.files(loader_module)
+                for item in pkg_files.iterdir():
+                    name = item.name
+                    if name.endswith("help.yaml") or name.endswith("help.yml"):
+                        results.append(str(item))
         return results
 
     @staticmethod
     def _parse_yaml_from_string(text, help_file_path):
+        import yaml
+
         dir_name, base_name = os.path.split(help_file_path)
         pretty_file_path = os.path.join(os.path.basename(dir_name), base_name)
 

src/azure-cli-core/azure/cli/core/aaz/_client.py

@@ -8,7 +8,6 @@
 from azure.core.polling.base_polling import LocationPolling, StatusCheckPolling
 from abc import abstractmethod
 
-from ._poller import AAZNoPolling, AAZBasePolling
 from azure.cli.core.cloud import (CloudEndpointNotSetException, CloudSuffixNotSetException,
                                   CloudNameEnum as _CloudNameEnum)
 
@@ -111,6 +110,7 @@ def send_request(self, request, stream=False, **kwargs):  # pylint: disable=argu
     def build_lro_polling(self, no_wait, initial_session, deserialization_callback, error_callback,
                           lro_options=None, path_format_arguments=None):
         from azure.core.polling.base_polling import OperationResourcePolling
+        from ._poller import AAZNoPolling, AAZBasePolling
         if no_wait == True:  # noqa: E712, pylint: disable=singleton-comparison
             polling = AAZNoPolling()
         else:
@@ -233,6 +233,7 @@ def _build_per_call_policies(cls, ctx, **kwargs):
     def build_lro_polling(self, no_wait, initial_session, deserialization_callback, error_callback,
                           lro_options=None, path_format_arguments=None):
         from azure.mgmt.core.polling.arm_polling import AzureAsyncOperationPolling, BodyContentPolling
+        from ._poller import AAZNoPolling, AAZBasePolling
         if no_wait == True:  # noqa: E712, pylint: disable=singleton-comparison
             polling = AAZNoPolling()
         else:

src/azure-cli-core/azure/cli/core/aaz/_command.py

@@ -22,7 +22,6 @@
 from ._base import AAZUndefined, AAZBaseValue
 from ._field_type import AAZObjectType
 from ._paging import AAZPaged
-from ._poller import AAZLROPoller
 from ._command_ctx import AAZCommandCtx
 from .exceptions import AAZUnknownFieldError, AAZUnregisteredArg
 from .utils import get_aaz_profile_module_name
@@ -235,6 +234,7 @@ def processor(schema, result):
     def build_lro_poller(self, executor, extract_result):
         """ Build AAZLROPoller instance to support long running operation
         """
+        from ._poller import AAZLROPoller
         polling_generator = executor()
         if self.ctx.lro_no_wait:
             # run until yield the first polling

src/azure-cli-core/azure/cli/core/commands/__init__.py

@@ -29,7 +29,6 @@
     get_command_type_kwarg, read_file_content, get_arg_list, poller_classes)
 from azure.cli.core.local_context import LocalContextAction
 from azure.cli.core import telemetry
-from azure.cli.core.commands.progress import IndeterminateProgressBar
 
 from knack.arguments import CLICommandArgument
 from knack.commands import CLICommand, CommandGroup, PREVIEW_EXPERIMENTAL_CONFLICT_ERROR
@@ -1035,10 +1034,20 @@ def __init__(self, cli_ctx, start_msg='', finish_msg='', poller_done_interval_ms
         self.deploy_dict = {}
         self.last_progress_report = datetime.datetime.now()
 
-        self.progress_bar = None
+        self._progress_bar = None
         disable_progress_bar = self.cli_ctx.config.getboolean('core', 'disable_progress_bar', False)
-        if not disable_progress_bar and not cli_ctx.only_show_errors:
-            self.progress_bar = progress_bar if progress_bar is not None else IndeterminateProgressBar(cli_ctx)
+        self.disable_progress_bar = disable_progress_bar or cli_ctx.only_show_errors
+        if not self.disable_progress_bar:
+            self._progress_bar = progress_bar
+
+    @property
+    def progress_bar(self):
+        if self.disable_progress_bar:
+            return None
+        if self._progress_bar is None:
+            from azure.cli.core.commands.progress import IndeterminateProgressBar
+            self._progress_bar = IndeterminateProgressBar(self.cli_ctx)
+        return self._progress_bar
 
     def _delay(self):
         time.sleep(self.poller_done_interval_ms / 1000.0)

src/azure-cli-core/azure/cli/core/commands/parameters.py

@@ -5,7 +5,7 @@
 
 
 import argparse
-import platform
+import sys
 
 from azure.cli.core import EXCLUDED_PARAMS
 from azure.cli.core.commands.constants import CLI_PARAM_KWARGS, CLI_POSITIONAL_PARAM_KWARGS
@@ -274,7 +274,7 @@ def get_location_type(cli_ctx):
     validator=generate_deployment_name
 )
 
-quotes = '""' if platform.system() == 'Windows' else "''"
+quotes = '""' if sys.platform == 'win32' else "''"
 quote_text = 'Use {} to clear existing tags.'.format(quotes)
 
 tags_type = CLIArgumentType(

src/azure-cli-core/azure/cli/core/commands/progress.py

@@ -4,8 +4,6 @@
 # --------------------------------------------------------------------------------------------
 import sys
 
-from humanfriendly.terminal.spinners import Spinner
-
 BAR_LEN = 70
 EMPTY_LINE = ' ' * BAR_LEN
 
@@ -114,6 +112,7 @@ def write(self, args):
         :param args: dictionary containing key 'message'
         """
         if self.spinner is None:
+            from humanfriendly.terminal.spinners import Spinner
             self.spinner = Spinner(  # pylint: disable=no-member
                 label='In Progress', stream=self.out, hide_cursor=False)
         msg = args.get('message', 'In Progress')
@@ -178,10 +177,15 @@ def __init__(self, cli_ctx, message="Running"):
         self.message = message
         self.hook = self.cli_ctx.get_progress_controller(
             det=False,
-            spinner=Spinner(  # pylint: disable=no-member
-                label='Running',
-                stream=sys.stderr,
-                hide_cursor=False))
+            spinner=self._create_spinner())
+
+    @staticmethod
+    def _create_spinner():
+        from humanfriendly.terminal.spinners import Spinner
+        return Spinner(  # pylint: disable=no-member
+            label='Running',
+            stream=sys.stderr,
+            hide_cursor=False)
 
     def begin(self):
         self.hook.begin()

src/azure-cli-core/azure/cli/core/commands/validators.py

@@ -5,7 +5,6 @@
 
 import argparse
 import time
-import random
 
 from azure.cli.core.profiles import ResourceType
 
@@ -67,6 +66,7 @@ def validate_key_value_pairs(string):
 
 def generate_deployment_name(namespace):
     if not namespace.deployment_name:
+        import random
         namespace.deployment_name = \
             'azurecli{}{}'.format(str(time.time()), str(random.randint(1, 100000)))
 

src/azure-cli-core/azure/cli/core/decorators.py

@@ -10,7 +10,6 @@
 that it doesn't import modules other than those in the Python Standard Library
 """
 
-import hashlib
 from functools import wraps
 
 from knack.log import get_logger
@@ -43,6 +42,7 @@ def call_once(factory_func):
     def _wrapped(*args, **kwargs):
         if not factory_func.executed:
             factory_func.cached_result = factory_func(*args, **kwargs)
+            factory_func.executed = True
 
         return factory_func.cached_result
 
@@ -57,6 +57,7 @@ def hash256_result(func):
 
     @wraps(func)
     def _decorator(*args, **kwargs):
+        import hashlib
         val = func(*args, **kwargs)
         if val is None:
             raise ValueError('Return value is None')

src/azure-cli-core/azure/cli/core/extension/__init__.py

@@ -10,7 +10,6 @@
 import re
 from sysconfig import get_path
 
-import pkginfo
 from knack.config import CLIConfig
 from knack.log import get_logger
 from azure.cli.core._config import GLOBAL_CONFIG_DIR, ENV_VAR_PREFIX
@@ -134,6 +133,7 @@ def get_version(self):
 
     def get_metadata(self):
         from glob import glob
+        import pkginfo
 
         metadata = {}
         ext_dir = self.path or get_extension_path(self.name)
@@ -213,6 +213,8 @@ def get_version(self):
         return self.metadata.get('version')
 
     def get_metadata(self):
+        import pkginfo
+
         metadata = {}
         ext_dir = self.path
         if not ext_dir or not os.path.isdir(ext_dir):