README
1 Python Misc subdirectory
2 ========================
3
4 This directory contains files that wouldn't fit in elsewhere. Some
5 documents are only of historic importance.
6
7 Files found here
8 ----------------
9
10 ACKS Acknowledgements
11 AIX-NOTES Notes for building Python on AIX
12 BeOS-NOTES Notes for building on BeOS
13 BeOS-setup.py setup.py replacement for BeOS, see BeOS-NOTES
14 build.sh Script to build and test latest Python from the repository
15 cheatsheet Quick summary of Python by Ken Manheimer
16 developers.txt A history of who got developer permissions, and why
17 gdbinit Handy stuff to put in your .gdbinit file, if you use gdb
18 HISTORY News from previous releases -- oldest last
19 indent.pro GNU indent profile approximating my C style
20 maintainers.rst A list of maintainers for library modules
21 NEWS News for this release (for some meaning of "this")
22 NEWS.help How to edit NEWS
23 Porting Mini-FAQ on porting to new platforms
24 PURIFY.README Information for Purify users
25 pymemcompat.h Memory interface compatibility file.
26 python-config.in Python script template for python-config
27 python.man UNIX man page for the python interpreter
28 python-mode.el Emacs mode for editing Python programs
29 python.pc.in Package configuration info template for pkg-config
30 python-wing.wpr Wing IDE project file
31 README The file you're reading now
32 README.coverity Information about running Coverity's Prevent on Python
33 README.klocwork Information about running Klocwork's K7 on Python
34 README.OpenBSD Help for building problems on OpenBSD
35 README.valgrind Information for Valgrind users, see valgrind-python.supp
36 RFD Request For Discussion about a Python newsgroup
37 setuid-prog.c C helper program for set-uid Python scripts
38 SpecialBuilds.txt Describes extra symbols you can set for debug builds
39 TextMate A TextMate bundle for Python development
40 valgrind-python.supp Valgrind suppression file, see README.valgrind
41 vgrindefs Python configuration for vgrind (a generic pretty printer)
42 Vim Python development utilities for the Vim editor
43
README.AIX
1
2 This documentation tries to help people who intend to use Python on
3 AIX.
4
5 There used to be many issues with Python on AIX, but the major ones
6 have been corrected for version 3.2, so that Python should now work
7 rather well on this platform. The remaining known issues are listed in
8 this document.
9
10
11 ======================================================================
12 Compiling Python
13 ----------------------------------------------------------------------
14
15 You can compile Python with gcc or the native AIX compiler. The native
16 compiler used to give better performances on this system with older
17 versions of Python. With Python 3.2 it may not be the case anymore,
18 as this compiler does not allow compiling Python with computed gotos.
19 Some benchmarks need to be done.
20
21 Compiling with gcc:
22
23 cd Python-3.2
24 CC=gcc OPT="-O2" ./configure --enable-shared
25 make
26
27 There are various aliases for the native compiler. The recommended
28 alias for compiling Python is 'xlc_r', which provides a better level of
29 compatibility and handles thread initialization properly.
30
31 It is a good idea to add the '-qmaxmem=70000' option, otherwise the
32 compiler considers various files too complex to optimize.
33
34 Compiling with xlc:
35
36 cd Python-3.2
37 CC=xlc_r OPT="-O2 -qmaxmem=70000" ./configure --without-computed-gotos --enable-shared
38 make
39
40 Note:
41 On AIX 5.3 and earlier, you will also need to specify the
42 "--disable-ipv6" flag to configure. This has been corrected in AIX
43 6.1.
44
45
46 ======================================================================
47 Memory Limitations
48 ----------------------------------------------------------------------
49
50 Note: this section may not apply when compiling Python as a 64 bit
51 application.
52
53 By default on AIX each program gets one segment register for its data
54 segment. As each segment register covers 256 MB, a Python program that
55 would use more than 256MB will raise a MemoryError. The standard
56 Python test suite is one such application.
57
58 To allocate more segment registers to Python, you must use the linker
59 option -bmaxdata or the ldedit tool to specify the number of bytes you
60 need in the data segment.
61
62 For example, if you want to allow 512MB of memory for Python (this is
63 enough for the test suite to run without MemoryErrors), you should run
64 the following command at the end of compilation:
65
66 ldedit -b maxdata:0x20000000 ./python
67
68 You can allow up to 2GB of memory for Python by using the value
69 0x80000000 for maxdata.
70
71 It is also possible to go beyond 2GB of memory by activating Large
72 Page Use. You should consult the IBM documentation if you need to use
73 this option. You can also follow the discussion of this problem
74 in issue 11212 at bugs.python.org.
75
76 http://publib.boulder.ibm.com/infocenter/aix/v6r1/index.jsp?topic=/com.ibm.aix.cmds/doc/aixcmds3/ldedit.htm
77
78
79 ======================================================================
80 Known issues
81 ----------------------------------------------------------------------
82
83 Those issues are currently affecting Python on AIX:
84
85 * Python has not been fully tested on AIX when compiled as a 64 bit
86 application.
87
88 * issue 3526: the memory used by a Python process will never be
89 released to the system. If you have a Python application on AIX that
90 uses a lot of memory, you should read this issue and you may
91 consider using the provided patch that implements a custom malloc
92 implementation
93
94 * issue 11184: support for large files is currently broken
95
96 * issue 11185: os.wait4 does not behave correctly with option WNOHANG
97
98 * issue 1745108: there may be some problems with curses.panel
99
100 * issue 11192: test_socket fails
101
102 * issue 11190: test_locale fails
103
104 * issue 11193: test_subprocess fails
105
106 * issue 9920: minor arithmetic issues in cmath
107
108 * issue 11215: test_fileio fails
109
110 * issue 11188: test_time fails
111
112
113 ======================================================================
114 Implementation details for developers
115 ----------------------------------------------------------------------
116
117 Python and python modules can now be built as shared libraries on AIX
118 as usual.
119
120 AIX shared libraries require that an "export" and "import" file be
121 provided at compile time to list all extern symbols which may be
122 shared between modules. The "export" file (named python.exp) for the
123 modules and the libraries that belong to the Python core is created by
124 the "makexp_aix" script before performing the link of the python
125 binary. It lists all global symbols (exported during the link) of the
126 modules and the libraries that make up the python executable.
127
128 When shared library modules (.so files) are made, a second shell
129 script is invoked. This script is named "ld_so_aix" and is also
130 provided with the distribution in the Modules subdirectory. This
131 script acts as an "ld" wrapper which hides the explicit management of
132 "export" and "import" files; it adds the appropriate arguments (in the
133 appropriate order) to the link command that creates the shared module.
134 Among other things, it specifies that the "python.exp" file is an
135 "import" file for the shared module.
136
137 This mechanism should be transparent.
138
README.coverity
1
2 Coverity has a static analysis tool (Prevent) which is similar to Klocwork.
3 They run their tool on the Python source code (SVN head) on a daily basis.
4 The results are available at:
5
6 http://scan.coverity.com/
7
8 About 20 people have access to the analysis reports. Other
9 people can be added by request.
10
11 Prevent was first run on the Python 2.5 source code in March 2006.
12 There were originally about 100 defects reported. Some of these
13 were false positives. Over 70 issues were uncovered.
14
15 Each warning has a unique id and comments that can be made on it.
16 When checking in changes due to a warning, the unique id
17 as reported by the tool was added to the SVN commit message.
18
19 False positives were annotated so that the comments can
20 be reviewed and reversed if the analysis was incorrect.
21
22 Contact python-dev (a] python.org for more information.
23
README.Emacs
1 =============
2 Emacs support
3 =============
4
5 If you want to edit Python code in Emacs, you should download python-mode.el
6 and install it somewhere on your load-path. See the project page to download:
7
8 https://launchpad.net/python-mode
9
10 While Emacs comes with a python.el file, it is not recommended.
11 python-mode.el is maintained by core Python developers and is generally
12 considered more Python programmer friendly. For example, python-mode.el
13 includes a killer feature called `pdbtrack` which allows you to set a pdb
14 breakpoint in your code, run your program in an Emacs shell buffer, and do gud
15 style debugging when the breakpoint is hit.
16
17 python-mode.el is compatible with both GNU Emacs from the FSF, and XEmacs.
18
19 For more information and bug reporting, see the above project page. For help,
20 development, or discussions, see the python-mode mailing list:
21
22 http://mail.python.org/mailman/listinfo/python-mode
23
24
25 ..
26 Local Variables:
27 mode: indented-text
28 indent-tabs-mode: nil
29 sentence-end-double-space: t
30 fill-column: 78
31 coding: utf-8
32 End:
33
README.klocwork
1
2 Klocwork has a static analysis tool (K7) which is similar to Coverity.
3 They will run their tool on the Python source code on demand.
4 The results are available at:
5
6 https://opensource.klocwork.com/
7
8 Currently, only Neal Norwitz has access to the analysis reports. Other
9 people can be added by request.
10
11 K7 was first run on the Python 2.5 source code in mid-July 2006.
12 This is after Coverity had been making their results available.
13 There were originally 175 defects reported. Most of these
14 were false positives. However, there were numerous real issues
15 also uncovered.
16
17 Each warning has a unique id and comments that can be made on it.
18 When checking in changes due to a K7 report, the unique id
19 as reported by the tool was added to the SVN commit message.
20 A comment was added to the K7 warning indicating the SVN revision
21 in addition to any analysis.
22
23 False positives were also annotated so that the comments can
24 be reviewed and reversed if the analysis was incorrect.
25
26 A second run was performed on 10-Aug-2006. The tool was tuned to remove
27 some false positives and perform some additional checks. ~150 new
28 warnings were produced, primarily related to dereferencing NULL pointers.
29
30 Contact python-dev (a] python.org for more information.
31
README.OpenBSD
1
2 2005-01-08
3
4 If you are have a problem building on OpenBSD and see output like this
5 while running configure:
6
7 checking curses.h presence... yes
8 configure: WARNING: curses.h: present but cannot be compiled
9 configure: WARNING: curses.h: check for missing prerequisite headers?
10 configure: WARNING: curses.h: see the Autoconf documentation
11 configure: WARNING: curses.h: section "Present But Cannot Be Compiled"
12 configure: WARNING: curses.h: proceeding with the preprocessor's result
13 configure: WARNING: curses.h: in the future, the compiler will take precedence
14
15 there is likely a problem that will prevent building python.
16 If you see the messages above and are able to completely build python,
17 please tell python-dev (a] python.org indicating your version of OpenBSD
18 and any other relevant system configuration.
19
20 The build error that occurs while making may look something like this:
21
22 /usr/include/sys/event.h:53: error: syntax error before "u_int"
23 /usr/include/sys/event.h:55: error: syntax error before "u_short"
24
25 To fix this problem, you will probably need update Python's configure
26 script to disable certain options. Search for a line that looks like:
27
28 OpenBSD/2.* | OpenBSD/3.@<:@012345678@:>@)
29
30 If your version is not in that list, e.g., 3.9, add the version
31 number. In this case, you would just need to add a 9 after the 8.
32 If you modify configure.ac, you will need to regenerate configure
33 with autoconf.
34
35 If your version is already in the list, this is not a known problem.
36 Please submit a bug report here:
37
38 http://sourceforge.net/tracker/?group_id=5470&atid=105470
39
README.valgrind
1 This document describes some caveats about the use of Valgrind with
2 Python. Valgrind is used periodically by Python developers to try
3 to ensure there are no memory leaks or invalid memory reads/writes.
4
5 If you don't want to read about the details of using Valgrind, there
6 are still two things you must do to suppress the warnings. First,
7 you must use a suppressions file. One is supplied in
8 Misc/valgrind-python.supp. Second, you must do one of the following:
9
10 * Uncomment Py_USING_MEMORY_DEBUGGER in Objects/obmalloc.c,
11 then rebuild Python
12 * Uncomment the lines in Misc/valgrind-python.supp that
13 suppress the warnings for PyObject_Free and PyObject_Realloc
14
15 If you want to use Valgrind more effectively and catch even more
16 memory leaks, you will need to configure python --without-pymalloc.
17 PyMalloc allocates a few blocks in big chunks and most object
18 allocations don't call malloc, they use chunks doled about by PyMalloc
19 from the big blocks. This means Valgrind can't detect
20 many allocations (and frees), except for those that are forwarded
21 to the system malloc. Note: configuring python --without-pymalloc
22 makes Python run much slower, especially when running under Valgrind.
23 You may need to run the tests in batches under Valgrind to keep
24 the memory usage down to allow the tests to complete. It seems to take
25 about 5 times longer to run --without-pymalloc.
26
27 Apr 15, 2006:
28 test_ctypes causes Valgrind 3.1.1 to fail (crash).
29 test_socket_ssl should be skipped when running valgrind.
30 The reason is that it purposely uses uninitialized memory.
31 This causes many spurious warnings, so it's easier to just skip it.
32
33
34 Details:
35 --------
36 Python uses its own small-object allocation scheme on top of malloc,
37 called PyMalloc.
38
39 Valgrind may show some unexpected results when PyMalloc is used.
40 Starting with Python 2.3, PyMalloc is used by default. You can disable
41 PyMalloc when configuring python by adding the --without-pymalloc option.
42 If you disable PyMalloc, most of the information in this document and
43 the supplied suppressions file will not be useful. As discussed above,
44 disabling PyMalloc can catch more problems.
45
46 If you use valgrind on a default build of Python, you will see
47 many errors like:
48
49 ==6399== Use of uninitialised value of size 4
50 ==6399== at 0x4A9BDE7E: PyObject_Free (obmalloc.c:711)
51 ==6399== by 0x4A9B8198: dictresize (dictobject.c:477)
52
53 These are expected and not a problem. Tim Peters explains
54 the situation:
55
56 PyMalloc needs to know whether an arbitrary address is one
57 that's managed by it, or is managed by the system malloc.
58 The current scheme allows this to be determined in constant
59 time, regardless of how many memory areas are under pymalloc's
60 control.
61
62 The memory pymalloc manages itself is in one or more "arenas",
63 each a large contiguous memory area obtained from malloc.
64 The base address of each arena is saved by pymalloc
65 in a vector. Each arena is carved into "pools", and a field at
66 the start of each pool contains the index of that pool's arena's
67 base address in that vector.
68
69 Given an arbitrary address, pymalloc computes the pool base
70 address corresponding to it, then looks at "the index" stored
71 near there. If the index read up is out of bounds for the
72 vector of arena base addresses pymalloc maintains, then
73 pymalloc knows for certain that this address is not under
74 pymalloc's control. Otherwise the index is in bounds, and
75 pymalloc compares
76
77 the arena base address stored at that index in the vector
78
79 to
80
81 the arbitrary address pymalloc is investigating
82
83 pymalloc controls this arbitrary address if and only if it lies
84 in the arena the address's pool's index claims it lies in.
85
86 It doesn't matter whether the memory pymalloc reads up ("the
87 index") is initialized. If it's not initialized, then
88 whatever trash gets read up will lead pymalloc to conclude
89 (correctly) that the address isn't controlled by it, either
90 because the index is out of bounds, or the index is in bounds
91 but the arena it represents doesn't contain the address.
92
93 This determination has to be made on every call to one of
94 pymalloc's free/realloc entry points, so its speed is critical
95 (Python allocates and frees dynamic memory at a ferocious rate
96 -- everything in Python, from integers to "stack frames",
97 lives in the heap).
98