Speed up pip list --outdated

news/7962.bugfix

@@ -0,0 +1 @@
+`pip list --outdated` version fetching is multi-threaded

src/pip/_internal/commands/list.py

@@ -5,8 +5,10 @@
 
 import json
 import logging
+from multiprocessing.pool import ThreadPool
 
 from pip._vendor import six
+from pip._vendor.requests.adapters import DEFAULT_POOLSIZE
 from pip._vendor.six.moves import zip_longest
 
 from pip._internal.cli import cmdoptions
@@ -183,9 +185,17 @@ def iter_packages_latest_infos(self, packages, options):
         with self._build_session(options) as session:
             finder = self._build_package_finder(options, session)
 
-            for dist in packages:
+            # Doing multithreading in Python 2 compatible way
+            executor = ThreadPool(DEFAULT_POOLSIZE)
+            all_candidates_list = executor.map(
+                finder.find_all_candidates,
+                [dist.key for dist in packages]
+            )
+            executor.close()
+            executor.join()
+
+            for dist, all_candidates in zip(packages, all_candidates_list):
                 typ = 'unknown'
-                all_candidates = finder.find_all_candidates(dist.key)
                 if not options.pre:
                     # Remove prereleases
                     all_candidates = [candidate for candidate in all_candidates

src/pip/_internal/utils/logging.py

@@ -104,6 +104,8 @@ def indent_log(num=2):
     A context manager which will cause the log output to be indented for any
     log messages emitted inside it.
     """
+    # For thread-safety
+    _log_state.indentation = get_indentation()
     _log_state.indentation += num
     try:
         yield