More PEP 432 updates

- avoid "-m site" when describing how to explore sys.path
- provide example startup times for 2.7, 3.2 and 3.3 on my system
- misc notes on things to be documented about the status quo

pep-0432.txt

@@ -124,9 +124,33 @@ tear down the interpreter::
 
    python3 -m timeit -s "from subprocess import call" "call(['./python', '-c', 'pass'])"
 
-If this simple check suggests that any changes may pose a performance
+Current numbers on my system for 2.7, 3.2 and 3.3 (using the 3.3
-problem, then a more sophisticated microbenchmark will be developed to assist
+subprocess and timeit modules to execute the check, all with non-debug
-in investigation.
+builds)::
+
+    # Python 2.7
+    $ py33/python -m timeit -s "from subprocess import call" "call(['py27/python', '-c', 'pass'])"
+    100 loops, best of 3: 17.8 msec per loop
+    # Python 3.2
+    $ py33/python -m timeit -s "from subprocess import call" "call(['py32/python', '-c', 'pass'])"
+    10 loops, best of 3: 39 msec per loop
+    # Python 3.3
+    $ py33/python -m timeit -s "from subprocess import call" "call(['py33/python', '-c', 'pass'])"
+    10 loops, best of 3: 25.3 msec per loop
+
+Improvements in the import system and the Unicode support already resulted
+in a more than 30% improvement in startup time in Python 3.3 relative to
+3.2. Python 3.3 is still slightly slower to start than Python 2.7 due to the
+additional infrastructure that needs to be put in place to support the Unicode
+based text model.
+
+This PEP is not expected to have any significant effect on the startup time,
+as it is aimed primarily at *reordering* the existing initialisation
+sequence, without making substantial changes to the individual steps.
+
+However, if this simple check suggests that the proposed changes to the
+initialisation sequence may pose a performance problem, then a more
+sophisticated microbenchmark will be developed to assist in investigation.
 
 
 Required Configuration Settings
@@ -151,7 +175,7 @@ be able to control the following aspects of the final interpreter state:
   * ``sys.getfsencoding``
   * ``os.fsencode``
   * ``os.fsdecode``
-* The IO encoding used by:
+* The IO encoding (if any) and the buffering used by:
   * ``sys.stdin``
   * ``sys.stdout``
   * ``sys.stderr``
@@ -297,20 +321,21 @@ directory from the list of directories added. Embedding applications
 can control this by setting the ``Py_NoUserSiteDirectory`` global variable.
 
 The following commands can be used to check the default path configurations
-for a given Python executable on a given system (after passing the entries
+for a given Python executable on a given system:
-through ``os.path.abspath``):
 
-* ``./python -m site`` - standard configuration
+* ``./python -c "import sys, pprint; pprint.pprint(sys.path)"``
-* ``./python -s -m site`` - user site directory disabled
+  - standard configuration
-* ``./python -S -m site`` - all site path modifications disabled
+* ``./python -s -c "import sys, pprint; pprint.pprint(sys.path)"``
+  - user site directory disabled
+* ``./python -S -c "import sys, pprint; pprint.pprint(sys.path)"``
+  - all site path modifications disabled
 
-(Note: on Python versions prior to 3.3, the last command won't have the
+(Note: you can see similar information using ``-m site`` instead of ``-c``,
-desired effect, as the explicit import of the site module will still make
+but this is slightly misleading as it calls ``os.abspath`` on all of the
-the implicit path modifications that should have been disabled by the ``-S``
+path entries (making relative path entries look absolute), and also causes
-option. The command
+problems in the last case, as on Python versions prior to 3.3, explicitly
-``./python -S -c "import sys, pprint; pprint.pprint(sys.path)"`` will
+importing site will carry out the path modifications ``-S`` avoids, while on
-display the desired information. That command can also be used to see
+3.3+ combining ``-m site`` with ``-S`` currently fails)
-the raw path entries without the ``os.path.abspath`` calls)
 
 The calculation of ``sys.path[0]`` is comparatively straightforward:
 
@@ -365,18 +390,22 @@ TBD: Cover the initialisation of the following in more detail:
 
 * The initial warning system state:
   * ``sys.warnoptions``
+  * (-W option, PYTHONWARNINGS)
 * Arbitrary extended options (e.g. to automatically enable ``faulthandler``):
   * ``sys._xoptions``
+  * (-X option)
 * The filesystem encoding used by:
   * ``sys.getfsencoding``
   * ``os.fsencode``
   * ``os.fsdecode``
-* The IO encoding used by:
+* The IO encoding and buffering used by:
   * ``sys.stdin``
   * ``sys.stdout``
   * ``sys.stderr``
+  * (-u option, PYTHONIOENCODING, PYTHONUNBUFFEREDIO)
 * Whether or not to implicitly cache bytecode files:
   * ``sys.dont_write_bytecode``
+  * (-B option, PYTHONDONTWRITEBYTECODE)
 * Whether or not to enforce correct case in filenames on case-insensitive
   platforms
   * ``os.environ["PYTHONCASEOK"]``
@@ -400,15 +429,15 @@ Much of the configuration of CPython is currently handled through C level
 global variables::
 
     Py_BytesWarningFlag
-    Py_DebugFlag
+    Py_DebugFlag (-d option)
-    Py_InspectFlag
+    Py_InspectFlag (-i option, PYTHONINSPECT)
     Py_InteractiveFlag
-    Py_OptimizeFlag
+    Py_OptimizeFlag (-O option, PYTHONOPTIMIZE)
-    Py_DontWriteBytecodeFlag
+    Py_DontWriteBytecodeFlag (-B option, PYTHONDONTWRITEBYTECODE)
-    Py_NoUserSiteDirectory
+    Py_NoUserSiteDirectory (-s option, PYTHONNOUSERSITE)
-    Py_NoSiteFlag
+    Py_NoSiteFlag (-S option)
     Py_UnbufferedStdioFlag
-    Py_VerboseFlag
+    Py_VerboseFlag (-v option, PYTHONVERBOSE)
 
 For the above variables, the conversion of command line options and
 environment variables to C global variables is handled by ``Py_Main``,
@@ -428,6 +457,9 @@ Finally, some interactive behaviour (such as printing the introductory
 banner) is triggered only when standard input is reported as a terminal
 connection by the operating system.
 
+TBD: Document how the "-x" option is handled (skips processing of the
+first comment line in the main script)
+
 Also see detailed sequence of operations notes at [1_]