Re: Quality control in open source development
On Oct 8, 8:43 am, Dave [EMAIL PROTECTED] wrote: With the open source licenses that allow redistribution of modified code, how do you keep someone unaffiliated with the Python community from creating his or her own version of python, and declaring it to be Python 2.6, or maybe Python 2.7 without any approval of anyone at the PSF? Maybe their code is terrible, and not even compatible with the rest of Python! How can the PSF, for example, maintain the quality and coheren of new code contributed to be part of Python, or derivative works that claim to be some future version of Python? If licensees can redisribute as they like, isn't this a huge problem? Is this dealt with be restricting use of the Python trademarks? Just curious.. Most trademark violations have occurred, to the best of my recollection, by commercial entities trying to usurp the popularity of an open-source endeavor for their own commercial gain. It is very rare that another in the open-source community will commandeer the good name of another project for his own purposes. This gives strong credence to the idea that the highly participatory nature of the open-source community serves as a strong, self-enforcing deterrent to negative acts of this nature. As far as quality assurance itself goes, independent, third-party unit test suites are easily engineered. Parties who do manage to succeed in releasing their own Python 2.7 can do so only by either making their product compatible with this third-party verification suite, or by not doing so. This leads to two situations: (1) If compatible, then the name Python 2.7 may well be accepted by the community, even if only in an allegorical sense (e.g., If PSF released Python 2.7, this product is how I envision it'd be like.). Alternatively, people will recognize the product as being Python- compatible, but otherwise an independent line of development -- e.g., a fork. The PSF can then release under a new set of version numbers (where everyone understands that 2.7 is an independent fork not endorsed by PSF), persue negotiations (ultimately terminating in legal action) to arrive at an acceptable product name, etc. If the PSF were feeling particularly benevolent, they could even accept some ideas from the 2.7 release into their own branch of development. (2) If incompatible, the product will gather a reputation of inferiority rapidly, and those clearly interested in Python will neither want nor have anything to do with this misbranded malfeasance. Again, independent verification is an example of the participatory nature of the community at large, and is a prime example of how concerned citizens can act collectively in their own interest, independently, to help ensure the quality of a socially-accepted product. -- http://mail.python.org/mailman/listinfo/python-list
Re: Using subprocess module to launch a shell shell script that itself forks a process
On Oct 7, 6:23 pm, Gabriel Genellina [EMAIL PROTECTED] wrote: Is your shell script doing something else, apart from invoking the java process? Obviously, yes. The script is some 150 lines long. But the hang-up occurs because of the forked Java process, not the other lines. If not, you could just invoke java directly from Python. Also, you set stdin=PIPE - is your java process expecting some input? you're not writing anything to stdin. It does not expect input from stdin. However, this does not affect any OTHER scripts or commands I run. Let's remember to look at the objective facts: for shell scripts that launch child processes of their own, Python hangs. For all other types of commands, it works 100% as expected. Anyway, it's better to use the communicate method instead (it uses select to read from both stdout and stderr): That doesn't help me. See http://docs.python.org/library/subprocess.html#subprocess.Popen.commu... I have. -- http://mail.python.org/mailman/listinfo/python-list
Re: Using subprocess module to launch a shell shell script that itself forks a process
On Oct 8, 11:31 am, Samuel A. Falvo II [EMAIL PROTECTED] wrote: I removed the stdin=PIPE argument, and this works. Many thanks for bringing this to my attention. OK, I am confused. After observing a bug where the code works every other time, like clockwork, I've used strace to figure out what is going on. In the times when it works, it's only the shell script complaining that it's already running. So, I'm right back to square one. Even _without_ setting stdin=PIPE, it fails to unblock. I'm left utterly bewildered. The only thing I can think of is that the JVM's stdout is tied to the shell script's stdout, because that's the only way it can remain open upon the termination of the child process. I suppose, at this point, the next place to look is in shell script syntax to find out how to detach the JVM from the script's process group. -- http://mail.python.org/mailman/listinfo/python-list
Re: Using subprocess module to launch a shell shell script that itself forks a process
On Oct 8, 11:24 am, Samuel A. Falvo II [EMAIL PROTECTED] wrote: It does not expect input from stdin. However, this does not affect any OTHER scripts or commands I run. OK, so, I'm very confused as to why this would matter. I removed the stdin=PIPE argument, and this works. Many thanks for bringing this to my attention. But, my question now is, WHY is this an issue? If the launched process doesn't read from its stdin, why would it block? Hence my question here: Let's remember to look at the objective facts: for shell scripts that launch child processes of their own, Python hangs. For all other types of commands, it works 100% as expected. Meaning, if I launched the Java process directly, it works fine. If I launch it from the shell script WITHOUT background execution, it works fine. But when I launch it WITH background execution (e.g., with the suffix), then it blocks. Any ideas, so I can write this into my log for future reference? Thanks. -- http://mail.python.org/mailman/listinfo/python-list
Using subprocess module to launch a shell shell script that itself forks a process
I have a shell script script.sh that launches a Java process in the background using the -operator, like so: #!/bin/bash java ... arguments here ... In my Python code, I want to invoke this shell script using the Subprocess module. Here is my code: def resultFromRunning_(command): Invokes a shell command, and returns the stdout response. Args: command: A string containing the complete shell command to run. Results: A string containing the output of the command executed. Raises: ValueError if a non-zero return code is returned from the shell. OSError if command isn't found, inappropriate permissions, etc. L = log4py.Logger().get_instance() L.info(Executing: + command) p = subprocess.Popen( command, shell=True, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, close_fds=True ) outputChannel = p.stdout output = outputChannel.read() result = p.wait() if result: raise(ShellError(command, result, output)) L.info(Result = + str(output)) return output When running the aforementioned code, it kicks off the shell script, and, the shell script kicks off the Java process. However, the Python code never returns from outputChannel.read() until I explicitly kill the Java process myself via the kill shell command. I've researched this issue on Google and various other websites, and maybe I'm missing the obvious, but I cannot seem to find any documentation relevant to this problem. Lots of references to bugs filed in the past, that appear to be fixed, or to websites talking about how the Popen module has a 64K limit on its data queue size, but nothing relevent to my situation. Can anyone inform me or point me to the appropriate documentation on how to properly invoke a shell command such that any spawned children processes don't cause Python to hang on me? I assume it has something to do with process groups, but I'm largely ignorant of how to control those. Thanks in advance. -- http://mail.python.org/mailman/listinfo/python-list
