[issue25489] sys.exit() caught in exception handler
Brian Sutherland added the comment:
On Wed, Oct 28, 2015 at 03:32:36PM +, Guido van Rossum wrote:
>
> Guido van Rossum added the comment:
>
> How about we extend loop.stop() so that you can pass it an exception to
> raise once the loop is stopped? This exception would then be thrown out of
> run_forever(). There may be some delay (callbacks already scheduled will
> run first) but it is how things were meant to be.
It is better than the current situation where to call loop.stop() and
have the correct exit code I would need to resort to a global variable.
I would then probably try to write an exception handler like this:
def exception_handler(loop, context):
loop.stop(context.get('exception', Exception('unknown error')))
And then hope I don't lose the traceback!
> FWIW this isn't really enough to ensure cleanup happens before destructors
> run -- when the loop exits, tasks may still be active unless you keep track
> of all of them and explicitly cancel them (and run the loop until they have
> processed the cancellation).
At least in my situation I don't think this is a problem, the objective
is to shut down the process quickly to prevent bad things happening.
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[issue25489] sys.exit() caught in exception handler
Brian Sutherland added the comment: On Wed, Oct 28, 2015 at 02:49:55PM +, R. David Murray wrote: > > R. David Murray added the comment: > > Using sys.exit means you are depending on garbage collection to clean > up all of your program's resources. In the general case this is a bad > idea. A better design is to call loop.stop, and then do cleanup > (which might involve calling some wait_closed functions via > loop.run_until_complete). If you just call sys.exit, your resources > may not get cleaned up correctly, or may not get cleaned up correctly > somewhat randomly due to the indeterminacies in the order in which > garbage collection is done. This may not matter for a simple program, > but I find it makes it easier for me if I just do it "the right way" > always :) I think it depends on the problem, sometimes "crash-only" software is safer. You have to design for immediate failure anyway, can't stop those pesky hardware failures. So if you always immediately crash there is only one, well-tested path to stopping a program. Also saves a lot of cleanup code writing;) Hmm, I suppose that means I should really be using os._exit(42) to avoid garbage collection... -- ___ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue25489> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue25489] sys.exit() caught in exception handler
Brian Sutherland added the comment: Calling loop.stop() means that I need other, more complex code, to store and return the non-zero exit status. -- ___ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue25489> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue25489] sys.exit() caught in exception handler
New submission from Brian Sutherland: Running the attached file with python3 shows that SystemExit is caught rather than causing the process to stop. That's quite surprising. -- components: asyncio files: test_sys_exit_in_exception_handler.py messages: 253529 nosy: gvanrossum, haypo, jinty, yselivanov priority: normal severity: normal status: open title: sys.exit() caught in exception handler versions: Python 3.5 Added file: http://bugs.python.org/file40867/test_sys_exit_in_exception_handler.py ___ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue25489> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue25489] sys.exit() caught in exception handler
Brian Sutherland added the comment:
the workaround I am using at the moment is this:
def handler(loop, context):
print('Got error, exiting')
loop.call_soon(sys.exit, 42)
which actually does cause the process to exit
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[issue16981] ImportError hides real error when there too many open files during an import
New submission from Brian Sutherland: When running Python inside PostgreSQL using plpython on OSX 10.7.5 I started coming across very strange and apparently random ImportErrors. For example, failing to find the stat module while importing site: Traceback (most recent call last): File /Users/jinty/.buildout/eggs/setuptools-0.6c11-py2.7.egg/site.py, line 73, in module __boot() File /Users/jinty/.buildout/eggs/setuptools-0.6c11-py2.7.egg/site.py, line 2, in __boot import sys, imp, os, os.path File /Users/jinty/src/mp/lib/python2.7/os.py, line 49, in module import posixpath as path File /Users/jinty/src/mp/lib/python2.7/posixpath.py, line 15, in module import stat ImportError: No module named stat I debugged this by using PYTHONVERBOSE and modifying import.c with the attached patch. I found that stat.py was not found because fopen() failed with Too many open files. There were not enough open files because OSX has insanely low limits and PostgreSQL was using a large chunk of that. ulimit -n 4096 resolved the errors. I spent a LOT of time trying to figure that out (see the thread at http://www.postgresql.org/message-id/20130114163014.GA600@Brians-MacBook-Air.local). The bug I wish to report is that the real error (Too many open files) is hidden by ImportError: No module named stat. For anyone who does not want to modify import.c and rebuild python, it is almost impossible to figure out what is really happening. -- files: patch-Python-import.c.diff keywords: patch messages: 180092 nosy: jinty priority: normal severity: normal status: open title: ImportError hides real error when there too many open files during an import type: behavior versions: Python 2.7 Added file: http://bugs.python.org/file28753/patch-Python-import.c.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue16981 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
Re: Making a calendar
On Sat, Feb 26, 2005 at 01:57:20PM +0100, Pete. wrote: I'm trying to make a calendar for my webpage, python and html is the only programming languages that I know, is it possible to make such a calendar with pythong code and some html. The Idea is that when I click the link calendar on my webpage, then the user will be linked to the calendar. The calendar should show one month at the time, and the user should be able to browse to the other month. I will make a script that puts events and such into a db ( I know how to do this) Then I need a script that puts the events from the db into the calendar, if every day in the calendar has a value id that part will not be hard. All this and more (perhaps overkill): http://www.schooltool.org/schoolbell -- Brian Sutherland It's 10 minutes, 5 if you walk fast. -- http://mail.python.org/mailman/listinfo/python-list
