Python-Dev March 2008

python-dev@python.org

142 participants
167 discussions

by Rotem Yaari

Hello everyone! We have been encountering several deadlocks in a threaded Python application which calls subprocess.Popen (i.e. fork()) in some of its threads. This has occurred on Python 2.4.1 on a 2.4.27 Linux kernel. Preliminary analysis of the hang shows that the child process blocks upon entering the execvp function, in which the import_lock is acquired due to the following line: def _ execvpe(file, args, env=None): from errno import ENOENT, ENOTDIR ... It is known that when forking from a pthreaded application, acquisition attempts on locks which were already locked by other threads while fork() was called will deadlock. Due to these oddities we were wondering if it would be better to extract the above import line from the execvpe call, to prevent lock acquisition attempts in such cases. Another workaround could be re-assigning a new lock to import_lock (such a thing is done with the global interpreter lock) at PyOS_AfterFork or pthread_atfork. We'd appreciate any opinions you might have on the subject. Thanks in advance, Yair and Rotem

10 years, 6 months

Re: subprocess and EINTR errnos

by Peter Astrand

On Wed, 10 Nov 2004, John P Speno wrote: Hi, sorry for the delayed response. > While using subprocess (aka popen5), I came across one potential gotcha. I've had > exceptions ending like this: > > File "test.py", line 5, in test > cmd = popen5.Popen(args, stdout=PIPE) > File "popen5.py", line 577, in __init__ > data = os.read(errpipe_read, 1048576) # Exceptions limited to 1 MB > OSError: [Errno 4] Interrupted system call > > (on Solaris 9) > > Would it make sense for subprocess to use a more robust read() function > which can handle these cases, i.e. when the parent's read on the pipe > to the child's stderr is interrupted by a system call, and returns EINTR? > I imagine it could catch EINTR and EAGAIN and retry the failed read(). I assume you are using signals in your application? The os.read above is not the only system call that can fail with EINTR. subprocess.py is full of other system calls that can fail, and I suspect that many other Python modules are as well. I've made a patch (attached) to subprocess.py (and test_subprocess.py) that should guard against EINTR, but I haven't committed it yet. It's quite large. Are Python modules supposed to handle EINTR? Why not let the C code handle this? Or, perhaps the signal module should provide a sigaction function, so that users can use SA_RESTART. Index: subprocess.py =================================================================== RCS file: /cvsroot/python/python/dist/src/Lib/subprocess.py,v retrieving revision 1.8 diff -u -r1.8 subprocess.py --- subprocess.py 7 Nov 2004 14:30:34 -0000 1.8 +++ subprocess.py 17 Nov 2004 19:42:30 -0000 @@ -888,6 +888,50 @@ pass + def _read_no_intr(self, fd, buffersize): + """Like os.read, but retries on EINTR""" + while True: + try: + return os.read(fd, buffersize) + except OSError, e: + if e.errno == errno.EINTR: + continue + else: + raise + + + def _read_all(self, fd, buffersize): + """Like os.read, but retries on EINTR, and reads until EOF""" + all = "" + while True: + data = self._read_no_intr(fd, buffersize) + all += data + if data == "": + return all + + + def _write_no_intr(self, fd, s): + """Like os.write, but retries on EINTR""" + while True: + try: + return os.write(fd, s) + except OSError, e: + if e.errno == errno.EINTR: + continue + else: + raise + + def _waitpid_no_intr(self, pid, options): + """Like os.waitpid, but retries on EINTR""" + while True: + try: + return os.waitpid(pid, options) + except OSError, e: + if e.errno == errno.EINTR: + continue + else: + raise + def _execute_child(self, args, executable, preexec_fn, close_fds, cwd, env, universal_newlines, startupinfo, creationflags, shell, @@ -963,7 +1007,7 @@ exc_value, tb) exc_value.child_traceback = ''.join(exc_lines) - os.write(errpipe_write, pickle.dumps(exc_value)) + self._write_no_intr(errpipe_write, pickle.dumps(exc_value)) # This exitcode won't be reported to applications, so it # really doesn't matter what we return. @@ -979,7 +1023,7 @@ os.close(errwrite) # Wait for exec to fail or succeed; possibly raising exception - data = os.read(errpipe_read, 1048576) # Exceptions limited to 1 MB + data = self._read_all(errpipe_read, 1048576) # Exceptions limited to 1 MB os.close(errpipe_read) if data != "": child_exception = pickle.loads(data) @@ -1003,7 +1047,7 @@ attribute.""" if self.returncode == None: try: - pid, sts = os.waitpid(self.pid, os.WNOHANG) + pid, sts = self._waitpid_no_intr(self.pid, os.WNOHANG) if pid == self.pid: self._handle_exitstatus(sts) except os.error: @@ -1015,7 +1059,7 @@ """Wait for child process to terminate. Returns returncode attribute.""" if self.returncode == None: - pid, sts = os.waitpid(self.pid, 0) + pid, sts = self._waitpid_no_intr(self.pid, 0) self._handle_exitstatus(sts) return self.returncode @@ -1049,27 +1093,33 @@ stderr = [] while read_set or write_set: - rlist, wlist, xlist = select.select(read_set, write_set, []) + try: + rlist, wlist, xlist = select.select(read_set, write_set, []) + except select.error, e: + if e[0] == errno.EINTR: + continue + else: + raise if self.stdin in wlist: # When select has indicated that the file is writable, # we can write up to PIPE_BUF bytes without risk # blocking. POSIX defines PIPE_BUF >= 512 - bytes_written = os.write(self.stdin.fileno(), input[:512]) + bytes_written = self._write_no_intr(self.stdin.fileno(), input[:512]) input = input[bytes_written:] if not input: self.stdin.close() write_set.remove(self.stdin) if self.stdout in rlist: - data = os.read(self.stdout.fileno(), 1024) + data = self._read_no_intr(self.stdout.fileno(), 1024) if data == "": self.stdout.close() read_set.remove(self.stdout) stdout.append(data) if self.stderr in rlist: - data = os.read(self.stderr.fileno(), 1024) + data = self._read_no_intr(self.stderr.fileno(), 1024) if data == "": self.stderr.close() read_set.remove(self.stderr) Index: test/test_subprocess.py =================================================================== RCS file: /cvsroot/python/python/dist/src/Lib/test/test_subprocess.py,v retrieving revision 1.14 diff -u -r1.14 test_subprocess.py --- test/test_subprocess.py 12 Nov 2004 15:51:48 -0000 1.14 +++ test/test_subprocess.py 17 Nov 2004 19:42:30 -0000 @@ -7,6 +7,7 @@ import tempfile import time import re +import errno mswindows = (sys.platform == "win32") @@ -35,6 +36,16 @@ fname = tempfile.mktemp() return os.open(fname, os.O_RDWR|os.O_CREAT), fname + def read_no_intr(self, obj): + while True: + try: + return obj.read() + except IOError, e: + if e.errno == errno.EINTR: + continue + else: + raise + # # Generic tests # @@ -123,7 +134,7 @@ p = subprocess.Popen([sys.executable, "-c", 'import sys; sys.stdout.write("orange")'], stdout=subprocess.PIPE) - self.assertEqual(p.stdout.read(), "orange") + self.assertEqual(self.read_no_intr(p.stdout), "orange") def test_stdout_filedes(self): # stdout is set to open file descriptor @@ -151,7 +162,7 @@ p = subprocess.Popen([sys.executable, "-c", 'import sys; sys.stderr.write("strawberry")'], stderr=subprocess.PIPE) - self.assertEqual(remove_stderr_debug_decorations(p.stderr.read()), + self.assertEqual(remove_stderr_debug_decorations(self.read_no_intr(p.stderr)), "strawberry") def test_stderr_filedes(self): @@ -186,7 +197,7 @@ 'sys.stderr.write("orange")'], stdout=subprocess.PIPE, stderr=subprocess.STDOUT) - output = p.stdout.read() + output = self.read_no_intr(p.stdout) stripped = remove_stderr_debug_decorations(output) self.assertEqual(stripped, "appleorange") @@ -220,7 +231,7 @@ stdout=subprocess.PIPE, cwd=tmpdir) normcase = os.path.normcase - self.assertEqual(normcase(p.stdout.read()), normcase(tmpdir)) + self.assertEqual(normcase(self.read_no_intr(p.stdout)), normcase(tmpdir)) def test_env(self): newenv = os.environ.copy() @@ -230,7 +241,7 @@ 'sys.stdout.write(os.getenv("FRUIT"))'], stdout=subprocess.PIPE, env=newenv) - self.assertEqual(p.stdout.read(), "orange") + self.assertEqual(self.read_no_intr(p.stdout), "orange") def test_communicate(self): p = subprocess.Popen([sys.executable, "-c", @@ -305,7 +316,8 @@ 'sys.stdout.write("\\nline6");'], stdout=subprocess.PIPE, universal_newlines=1) - stdout = p.stdout.read() + + stdout = self.read_no_intr(p.stdout) if hasattr(open, 'newlines'): # Interpreter with universal newline support self.assertEqual(stdout, @@ -343,7 +355,7 @@ def test_no_leaking(self): # Make sure we leak no resources - max_handles = 1026 # too much for most UNIX systems + max_handles = 10 # too much for most UNIX systems if mswindows: max_handles = 65 # a full test is too slow on Windows for i in range(max_handles): @@ -424,7 +436,7 @@ 'sys.stdout.write(os.getenv("FRUIT"))'], stdout=subprocess.PIPE, preexec_fn=lambda: os.putenv("FRUIT", "apple")) - self.assertEqual(p.stdout.read(), "apple") + self.assertEqual(self.read_no_intr(p.stdout), "apple") def test_args_string(self): # args is a string @@ -457,7 +469,7 @@ p = subprocess.Popen(["echo $FRUIT"], shell=1, stdout=subprocess.PIPE, env=newenv) - self.assertEqual(p.stdout.read().strip(), "apple") + self.assertEqual(self.read_no_intr(p.stdout).strip(), "apple") def test_shell_string(self): # Run command through the shell (string) @@ -466,7 +478,7 @@ p = subprocess.Popen("echo $FRUIT", shell=1, stdout=subprocess.PIPE, env=newenv) - self.assertEqual(p.stdout.read().strip(), "apple") + self.assertEqual(self.read_no_intr(p.stdout).strip(), "apple") def test_call_string(self): # call() function with string argument on UNIX @@ -525,7 +537,7 @@ p = subprocess.Popen(["set"], shell=1, stdout=subprocess.PIPE, env=newenv) - self.assertNotEqual(p.stdout.read().find("physalis"), -1) + self.assertNotEqual(self.read_no_intr(p.stdout).find("physalis"), -1) def test_shell_string(self): # Run command through the shell (string) @@ -534,7 +546,7 @@ p = subprocess.Popen("set", shell=1, stdout=subprocess.PIPE, env=newenv) - self.assertNotEqual(p.stdout.read().find("physalis"), -1) + self.assertNotEqual(self.read_no_intr(p.stdout).find("physalis"), -1) def test_call_string(self): # call() function with string argument on Windows /Peter Åstrand <astrand(a)lysator.liu.se>

10 years, 9 months

deprecating BaseException.message

by Brett Cannon

During the PyCon sprint I tried to make BaseException accept only a single argument and bind it to BaseException.message . I was successful (see the p3yk_no_args_on_exc branch), but it was very painful to pull off as anyone who sat around me the last three days of the sprint will tell you as they had to listen to me curse incessantly. Because of the pain that I went through in the transition and thus the lessons learned, Guido and I discussed it and we think it would be best to give up on forcing BaseException to accept only a single argument. I think it is still doable, but requires a multi-release transition period and not the one that 2.6 -> 3.0 is offering. And so Guido and I plan on deprecating BaseException.message as its entire point in existence was to help transition to what we are not going to have happen. =) Now that means BaseException.message might hold the record for shortest lived feature as it was only introduced in 2.5 and is now to be deprecated in 2.6 and removed in 2.7/3.0. =) Below is PEP 352, revised to reflect the removal of BaseException.messageand for letting the 'args' attribute stay (along with suggesting one should only pass a single argument to BaseException). Basically the interface for exceptions doesn't really change in 3.0 except for the removal of __getitem__. -------------------------------------------------------------------------- PEP: 352 Title: Required Superclass for Exceptions Version: $Revision: 53592 $ Last-Modified: $Date: 2007-01-28 21:54:11 -0800 (Sun, 28 Jan 2007) $ Author: Brett Cannon <brett(a)python.org> Guido van Rossum <guido(a)python.org> Status: Final Type: Standards Track Content-Type: text/x-rst Created: 27-Oct-2005 Post-History: Abstract ======== In Python 2.4 and before, any (classic) class can be raised as an exception. The plan for 2.5 was to allow new-style classes, but this makes the problem worse -- it would mean *any* class (or instance) can be raised! This is a problem as it prevents any guarantees from being made about the interface of exceptions. This PEP proposes introducing a new superclass that all raised objects must inherit from. Imposing the restriction will allow a standard interface for exceptions to exist that can be relied upon. It also leads to a known hierarchy for all exceptions to adhere to. One might counter that requiring a specific base class for a particular interface is unPythonic. However, in the specific case of exceptions there's a good reason (which has generally been agreed to on python-dev): requiring hierarchy helps code that wants to *catch* exceptions by making it possible to catch *all* exceptions explicitly by writing ``except BaseException:`` instead of ``except *:``. [#hierarchy-good]_ Introducing a new superclass for exceptions also gives us the chance to rearrange the exception hierarchy slightly for the better. As it currently stands, all exceptions in the built-in namespace inherit from Exception. This is a problem since this includes two exceptions (KeyboardInterrupt and SystemExit) that often need to be excepted from the application's exception handling: the default behavior of shutting the interpreter down without a traceback is usually more desirable than whatever the application might do (with the possible exception of applications that emulate Python's interactive command loop with ``>>>`` prompt). Changing it so that these two exceptions inherit from the common superclass instead of Exception will make it easy for people to write ``except`` clauses that are not overreaching and not catch exceptions that should propagate up. This PEP is based on previous work done for PEP 348 [#pep348]_. Requiring a Common Superclass ============================= This PEP proposes introducing a new exception named BaseException that is a new-style class and has a single attribute, ``args``. Below is the code as the exception will work in Python 3.0 (how it will work in Python 2.x is covered in the `Transition Plan`_ section):: class BaseException(object): """Superclass representing the base of the exception hierarchy. Provides a 'message' attribute that contains either the single argument to the constructor or the empty string. This attribute is used in the string representation for the exception. This is so that it provides the extra details in the traceback. """ def __init__(self, *args): """Set the 'message' attribute'""" self.args = args def __str__(self): """Return the str of 'message'""" if len(self.args) == 1: return str(self.args[0]) else: return str(self.args) def __repr__(self): return "%s(*%s)" % (self.__class__.__name__, repr(self.args)) No restriction is placed upon what may be passed in for ``args`` for backwards-compatibility reasons. In practice, though, only a single string argument should be used. This keeps the string representation of the exception to be a useful message about the exception that is human-readable; this is why the ``__str__`` method special-cases on length-1 ``args`` value. Including programmatic information (e.g., an error code number) should be stored as a separate attribute in a subclass. The ``raise`` statement will be changed to require that any object passed to it must inherit from BaseException. This will make sure that all exceptions fall within a single hierarchy that is anchored at BaseException [#hierarchy-good]_. This also guarantees a basic interface that is inherited from BaseException. The change to ``raise`` will be enforced starting in Python 3.0 (see the `Transition Plan`_ below). With BaseException being the root of the exception hierarchy, Exception will now inherit from it. Exception Hierarchy Changes =========================== With the exception hierarchy now even more important since it has a basic root, a change to the existing hierarchy is called for. As it stands now, if one wants to catch all exceptions that signal an error *and* do not mean the interpreter should be allowed to exit, you must specify all but two exceptions specifically in an ``except`` clause or catch the two exceptions separately and then re-raise them and have all other exceptions fall through to a bare ``except`` clause:: except (KeyboardInterrupt, SystemExit): raise except: ... That is needlessly explicit. This PEP proposes moving KeyboardInterrupt and SystemExit to inherit directly from BaseException. :: - BaseException |- KeyboardInterrupt |- SystemExit |- Exception |- (all other current built-in exceptions) Doing this makes catching Exception more reasonable. It would catch only exceptions that signify errors. Exceptions that signal that the interpreter should exit will not be caught and thus be allowed to propagate up and allow the interpreter to terminate. KeyboardInterrupt has been moved since users typically expect an application to exit when the press the interrupt key (usually Ctrl-C). If people have overly broad ``except`` clauses the expected behaviour does not occur. SystemExit has been moved for similar reasons. Since the exception is raised when ``sys.exit()`` is called the interpreter should normally be allowed to terminate. Unfortunately overly broad ``except`` clauses can prevent the explicitly requested exit from occurring. To make sure that people catch Exception most of the time, various parts of the documentation and tutorials will need to be updated to strongly suggest that Exception be what programmers want to use. Bare ``except`` clauses or catching BaseException directly should be discouraged based on the fact that KeyboardInterrupt and SystemExit almost always should be allowed to propagate up. Transition Plan =============== Since semantic changes to Python are being proposed, a transition plan is needed. The goal is to end up with the new semantics being used in Python 3.0 while providing a smooth transition for 2.x code. All deprecations mentioned in the plan will lead to the removal of the semantics starting in the version following the initial deprecation. Here is BaseException as implemented in the 2.x series:: class BaseException(object): """Superclass representing the base of the exception hierarchy. The __getitem__ method is provided for backwards-compatibility and will be deprecated at some point. """ def __init__(self, *args): """Set the 'args' attribute.""" self.args = args def __str__(self): """Return the str of args[0] or args, depending on length.""" return str(self.args[0] if len(self.args) <= 1 else self.args) def __repr__(self): func_args = repr(self.args) if self.args else "()" return self.__class__.__name__ + func_args def __getitem__(self, index): """Index into arguments passed in during instantiation. Provided for backwards-compatibility and will be deprecated. """ return self.args[index] Deprecation of features in Python 2.9 is optional. This is because it is not known at this time if Python 2.9 (which is slated to be the last version in the 2.x series) will actively deprecate features that will not be in 3.0 . It is conceivable that no deprecation warnings will be used in 2.9 since there could be such a difference between 2.9 and 3.0 that it would make 2.9 too "noisy" in terms of warnings. Thus the proposed deprecation warnings for Python 2.9 will be revisited when development of that version begins to determine if they are still desired. * Python 2.5 [done] - all standard exceptions become new-style classes - introduce BaseException - Exception, KeyboardInterrupt, and SystemExit inherit from BaseException - deprecate raising string exceptions * Python 2.6 - deprecate catching string exceptions - deprecate ``message`` attribute (see `Retracted Ideas`_) * Python 2.7 - deprecate raising exceptions that do not inherit from BaseException - remove ``message`` attribute * Python 2.8 - deprecate catching exceptions that do not inherit from BaseException * Python 2.9 - deprecate ``__getitem__`` (optional) * Python 3.0 [done] - drop everything that was deprecated above: + string exceptions (both raising and catching) + all exceptions must inherit from BaseException + drop ``__getitem__`` Retracted Ideas =============== A previous version of this PEP that was implemented in Python 2.5 included a 'message' attribute on BaseException. Its purpose was to begin a transition to BaseException accepting only a single argument. This was to tighten the interface and to force people to use attributes in subclasses to carry arbitrary information with an exception instead of cramming it all into ``args``. Unfortunately, while implementing the removal of the ``args`` attribute in Python 3.0 at the PyCon 2007 sprint [#pycon2007-sprint-email]_, it was discovered that the transition was very painful, especially for C extension modules. It was decided that it would be better to deprecate the ``message`` attribute in Python 2.6 (and remove in Python 2.7 and Python 3.0) and consider a more long-term transition strategy in Python 3.0 to remove multiple-argument support in BaseException in preference of accepting only a single argument. Thus the introduction of ``message`` and the original deprecation of ``args`` has been retracted. References ========== .. [#pep348] PEP 348 (Exception Reorganization for Python 3.0) http://www.python.org/peps/pep-0348.html .. [#hierarchy-good] python-dev Summary for 2004-08-01 through 2004-08-15 http://www.python.org/dev/summary/2004-08-01_2004-08-15.html#an-exception-i… .. [#SF_1104669] SF patch #1104669 (new-style exceptions) http://www.python.org/sf/1104669 .. [#pycon2007-sprint-email] python-3000 email ("How far to go with cleaning up exceptions") http://mail.python.org/pipermail/python-3000/2007-March/005911.html Copyright ========= This document has been placed in the public domain. .. Local Variables: mode: indented-text indent-tabs-mode: nil sentence-end-double-space: t fill-column: 70 End:

10 years, 12 months

Re: [Python-Dev] [Distutils] unicode bug in distutils

by Phillip J. Eby

At 02:47 PM 2/24/2007 -0600, Tarek Ziadé wrote: >I have created a setup.py file for distirbution and I bumped into >a small bug when i tried to set my name in the contact field (Tarek Ziadé) > >Using string (utf8 file): > >setup( > maintainer="Tarek Ziadé" >) > >leads to: > > File ".../lib/python2.5/distutils/command/register.py", line 162, in > send_metadata > auth) > File ".../lib/python2.5/distutils/command/register.py", line 257, in > post_to_server > value = unicode(value).encode("utf-8") >UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 10: >ordinal not in range(128) > > >Using unicode: > >setup( > maintainer=u"Tarek Ziadé" >) > >leads to: > > File ".../lib/python2.5/distutils/dist.py", line 1094, in write_pkg_file > file.write('Author: %s\n' % self.get_contact() ) >UnicodeEncodeError: 'ascii' codec can't encode character u'\xe9' in >position 18: ordinal not in range(128) > >I would propose a patch for this problem but i don't know what would be >the best input (i guess unicode > for names) At 05:45 PM 2/24/2007 -0500, Tres Seaver wrote: >Don't you still need to tell Python about the encoding of your string >literals [1] [2] ? E.g.:: That's not the problem, it's that the code that writes the PKG-INFO file doesn't handle Unicode. See distutils.dist.DistributionMetadata.write_pkg_info(). It needs to use a file with encoding support, if it's doing unicode However, there's currently no standard, as far as I know, for what encoding the PKG-INFO file should use. Meanwhile, the 'register' command accepts Unicode, but is broken in handling it. Essentially, the problem is that Python 2.5 broke this by adding a unicode *requirement* to the "register" command. Previously, register simply sent whatever you gave it, and the PKG-INFO writing code still does. Unfortunately, this means that there is no longer any one value that you can use for your name that will be accepted by both "register" and anything that writes a PKG-INFO file. Both register and write_pkg_info() are arguably broken here, and should be able to work with either strings or unicode, and degrade gracefully in the event of non-ASCII characters in a string. (Because even though "register" is only run by the package's author, users may run other commands that require a PKG-INFO, so a package prepared using Python <2.5 must still be usable with Python 2.5 distutils, and Python <2.5 allows 8-bit maintainer names.) Unfortunately, this isn't fixable until there's a new 2.5.x release. For previous Python versions, both register and write_pkg_info() accepted 8-bit strings and passed them on as-is, so the only workaround for this issue at the moment is to revert to Python 2.4 or less.

11 years

Python + Java Integration

by Chas Emerick

This may seem like it's coming out of left field for a minute, but bear with me. There is no doubt that Ruby's success is a concern for anyone who sees it as diminishing Python's status. One of the reasons for Ruby's success is certainly the notion (originally advocated by Bruce Tate, if I'm not mistaken) that it is the "next Java" -- the language and environment that mainstream Java developers are, or will, look to as a natural next step. One thing that would help Python in this "debate" (or, perhaps simply put it in the running, at least as a "next Java" candidate) would be if Python had an easier migration path for Java developers that currently rely upon various third-party libraries. The wealth of third-party libraries available for Java has always been one of its great strengths. Ergo, if Python had an easy-to-use, recommended way to use those libraries within the Python environment, that would be a significant advantage to present to Java developers and those who would choose Ruby over Java. Platform compatibility is always a huge motivator for those looking to migrate or upgrade. In that vein, I would point to JPype (http://jpype.sourceforge.net). JPype is a module that gives "python programs full access to java class libraries". My suggestion would be to either: (a) include JPype in the standard library, or barring that, (b) make a very strong push to support JPype (a) might be difficult or cumbersome technically, as JPype does need to build against Java headers, which may or may not be possible given the way that Python is distributed, etc. However, (b) is very feasible. I can't really say what "supporting JPype" means exactly -- maybe GvR and/or other heavyweights in the Python community make public statements regarding its existence and functionality, maybe JPype gets a strong mention or placement on python.org....all those details are obviously not up to me, and I don't know the workings of the "official" Python organizations enough to make serious suggestions. Regardless of the form of support, I think raising people's awareness of JPype and what it adds to the Python environment would be a Good Thing (tm). For our part, we've used JPype to make PDFTextStream (our previously Java-only PDF text extraction library) available and supported for Python. You can read some about it here: http://snowtide.com/PDFTextStream.Python And I've blogged about how PDFTextStream.Python came about, and how we worked with Steve Ménard, the maintainer of JPype, to make it all happen (watch out for this URL wrapping): http://blog.snowtide.com/2006/08/21/working-together-pythonjava-open- sourcecommercial Cheers, Chas Emerick Founder, Snowtide Informatics Systems Enterprise-class PDF content extraction cemerick(a)snowtide.com http://snowtide.com | +1 413.519.6365

11 years, 4 months

unittest's redundant assertions: asserts vs. failIf/Unlesses

by Gabriel Grant

Hi all, This gem from unittest.py is pretty much the opposite of "one obvious way": # Synonyms for assertion methods assertEqual = assertEquals = failUnlessEqual assertNotEqual = assertNotEquals = failIfEqual assertAlmostEqual = assertAlmostEquals = failUnlessAlmostEqual assertNotAlmostEqual = assertNotAlmostEquals = failIfAlmostEqual assertRaises = failUnlessRaises assert_ = assertTrue = failUnless assertFalse = failIf Could these be removed for 3k? There was a short discussion about this among some of those those present in the Python Core sprint room at PyCon today and most preferred the "assertEqual" form for [Not][Almost]Equal and Raises. With assertFalse vs. failIf (and assertTrue vs. failUnless) there was far less agreement. JUnit uses assertTrue exclusively, and most people said they feel that using assertTrue would be more consistent, but many (myself included) still think failUnless and failIf are much more natural. Another issue with assertTrue is that it doesn't actually test for 'True', strictly speaking, since it is based on equality, not identity. Its also interesting to note the original commit message: > r34209 | purcell | 2003-09-22 06:08:12 -0500 (Mon, 22 Sep 2003) > [...] > - New assertTrue and assertFalse aliases for comfort of JUnit users > [...] assertEqual (and its cousins) were already present at that point. In any case, if the decision is made to not use failUnless, something still needs to be done with assert_ vs. assertTrue. assert_ seems somewhat better to me, in that it has fewer characters, but I think that a case could certainly be made to keep both of these. I certainly don't have the authority to make a call on any of this, but if someone else decides what colour to paint this bike shed, I can try to get it done (hopefully with 2.6 warnings) tomorrow. Cheers, -Gabriel P.S. If you were in the sprint room and feel terribly misrepresented, please feel free to give me a swift kick both on-list and in person tomorrow morning.

11 years, 8 months

Documentation for ability to execute zipfiles & directories

by Nick Coghlan

A few months ago, 2.6 & 3.0 gained the ability to execute zipfiles and directories containing a __main__.py file (see [1] for details). The idea is that a whole application can be bundled into a zipfile containing a __main__.py module in its root directory, and then passed directly to the interpreter for execution, with the zipfile being inserted as the first entry on sys.path to allow easy access to the rest of the application code. It is inspired by Java's JAR option, but not needing an explicit interpreter option makes it more shebang friendly on *nix systems (it can also be mapped more easily to the existing Python file type handling on Windows). The ability to also execute directories containing a __main__.py was something of a side effect of the implementation technique, but was also considered valuable as it makes it much easier to develop such bundled applications (using a directory most of the time, and then bundling into a single zipfile prior to release). The part I'm struggling with now is where to document the way this feature works. Currently, the only real documentation we have of the command line invocation is in section 2.1 of the tutorial, and the idea of packaging whole applications as zipfiles seems far too esoteric to be covering it there. It doesn't really seem to fit in section 6 (covering modules and packages) either. Do we need a new appendix to the tutorial which goes into detail about the CPython interpreter's command line options, environment variables and details on what can be executed? Cheers, Nick. [1] http://bugs.python.org/issue1739468 -- Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia --------------------------------------------------------------- http://www.boredomandlaziness.org

11 years, 10 months

Buildbots for trunk are all red

by Facundo Batista

All fail in test_compiler.py. -- . Facundo Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org/ar/

11 years, 10 months

Re: [Python-Dev] Py3k and asyncore/asynchat

by Josiah Carlson

On Tue, Mar 25, 2008 at 11:26 PM, Neal Norwitz <nnorwitz(a)gmail.com> wrote: > Any reason this was sent just to me and not the list? Because gmail only replies to the sender by default. I need to remember to cc python-dev when I reply (I used the same email client for 8 1/2 years, remembering the quirks of gmail may take some time). > On Tue, Mar 25, 2008 at 10:34 PM, Josiah Carlson > <josiah.carlson(a)gmail.com> wrote: > > > > On Tue, Mar 25, 2008 at 9:00 PM, Neal Norwitz <nnorwitz(a)gmail.com> wrote: > > > On Thu, Feb 14, 2008 at 10:09 AM, Giampaolo Rodola' <gnewsg(a)gmail.com> wrote: > > > > On 14 Feb, 16:36, "Giampaolo Rodola'" <gne...(a)gmail.com> wrote: > > > > > Ok, I'll try to take a look at all asyncore/chat reports and try to > > > > > summarize them by splitting patches which solve bugs and patches which > > > > > add enhancements or functionalities. > > > > > > > > > > > > > > === Patches for existing issues === > > > > > > > > - 1736190 which includes fixes for the following issues among other > > > > improvements: > > > > - 1063924 (asyncore should handle ECONNRESET in send()) > > > > - 1736101 (asyncore should handle ECONNABORTED in recv()) > > > > - 760475 (handle_error() should call handle_close() instead of > > > > close()) > > > > - 1740572 (refill_buffer() should call handle_close() rather than > > > > close()) > > > > - 777588 (wrong "connection refused" behavior on Windows) > > > > - 889153 (wrong connect() behavior) > > > > - 953599 (asyncore misses socket closes when poll is used) > > > > - 1025525 (asyncore.file_dispatcher should not take fd as argument) > > > > > > > > - 1519 (async_chat.__init__() and asyncore.dispatcher.__init__ > > > > parameters inconsistency) > > > > - 1541 (Bad OOB data management when using asyncore with > > > > select.poll()) > > > > - 2073 (asynchat push always sends 512 bytes (ignoring > > > > ac_out_buffer_size)) > > > > > > > > > > > > === Open issues with no patches (need review) === > > > > > > > > - 658749 (asyncore connect() and winsock errors) > > > > - 1161031 (neverending warnings from asyncore) > > > > > > > > > > > > === Enhancements & new features === > > > > > > > > - 1641 (add delayed calls feature) > > > > - 1563 (conversion to py3k and some other changes) > > > > > > That's a lot of patches. My immediate concern is that test_asynchat > > > is very flaky and fails often. Sometimes it causes other tests to > > > fail. Is there a patch that addresses this? If you need examples, > > > just look through the buildbot mails that mention test_asynchat in: > > > http://mail.python.org/pipermail/python-checkins/ > > > > No, it's one patch. All of the fixes were performed mostly by myself > > last spring, tested and verified in personal servers, then re-used by > > Giampaolo in his async ftp server (which pointed out a few small bugs, > > which have been fixed). > > > > > > > Some platforms have more problems than others, but almost all > > > platforms have failed test_asynchat at one point or another. > > > > Certainly that is the case. And according to my reading of a few > > buildbot failures, aside from someone breaking asyncore itself, the > > failures seem to stem from the test being unable to create a port to > > listen on in order to test the server/client functionality. This is a > > buildbot configuration issue (per host), not an asyncore issue. > > That was the case a long time (~3? months) ago, but hasn't been the > case recently. See my recent message about the release. I'll look for it tomorrow. For reference, searches of 'site:mail.python.org test_asynchat failure buildbot' only seem to produce the socket listen error. If there is a better incantation to get google to produce the proper errors (and/or a link), I would appreciate the help. > > > Please break up the patches into 2 sets and prioritize the patches > > > with the set. > > > > > > Set #1: Patches that have a test and doc updates if required > > > Set #2: Patches that don't have a test or doc updates as required > > > > > > For the patches that fall into Set #1, list them in priority order. > > > Top priority would be a problem that fixes failures seen in the > > > buildbots. Next priority would go to the patches that solve more > > > serious problems. Post the results here. I will try to look at them. > > > > > > For every patch you list, make sure that it conforms to the proper > > > style (e.g, PEP 8) and is essentially perfect and ready for inclusion. > > > This means that there is a single file to download that contains all > > > the modifications. The changes are appropriately commented, lines are > > > less than 80 characters, etc. One of the modifications should be an > > > entry in Misc/NEWS. > > > > I lied earlier; really there are two patches. The first is a patch to > > asyncore.py and asynchat.py . It addresses those bugs that Giampaolo > > has listed, it is tested, and works. The second patch is to update > > the documentation to mention the sample methods in asynchat for use as > > examples, as well as any other changes to the language used in the > > documentation that I had made last spring, but which are out of date > > from my posting of the original patch. I can update the documentation > > in the next week. > > Can you provide a link to the patches? Do the patches include changes > to test_asyncore and test_asynchat? The next release is April 2. I > would like to commit any patches before Monday to ensure they are > stable. Can you get me the patches by this Saturday? See http://bugs.python.org/issue1736190 for an updated patch for the modules. The current test cases pass without issue, though we may want to add tests, which I need to look at the original patch and the original file from which it was created against, then compare it with the most recent changes to the tests from Facundo last June or July. I should have the time to get patches for tests and documentation by Monday. - Josiah

11 years, 11 months

Re: [Python-Dev] PEP 365 (Adding the pkg_resources module)

by Phillip J. Eby

At 10:53 AM 3/17/2008 -0500, Guido van Rossum wrote: >I don't think this should play games with scripts being overridden or >whatever. If a bootstrap script is to be installed it should have a >separate name. I'm not sure what the advantage is of a bootstrap >script over "python -m bootstrap_module ..." though. And -m also makes explicit: 1. that it's a Python-specific tool 2. which Python version it will apply to >The PEP suggests that other package managers also benefit. How do they >benefit if the bootstrap script installs setuptools? Because those other package managers depend, in fact, on setuptools, or at least pkg_resources... which was why the original proposal was to just include pkg_resources in the first place. :) >I'd also like to avoid the specific name "easy_install" for any of >this. That's a "brand name" (and a misleading one if you ask me, but >that's politics again :-). Ok, so if someone will propose a name and API for the thing, I'll implement it. (Assuming the proposed API is sane and reasonably implementable, of course.)

11 years, 11 months

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Python-Dev March 2008