On Wednesday 13 October 2010, Glyph Lefkowitz wrote:
To the extent that this is an intentional decision (it's at least half accidents of implementation) it's an attempt to allow twistd to actually display an error on the console if there is a serious error starting up, i.e. your plugin is not syntactically valid Python and it's just going to exit.
While I remember agreeing that it's unfortunate, I can't actually recall any issues with executing the script before forking. Do we have tickets for them? Can you describe a couple?
A long time ago I did run into trouble with the uid/gid being applied by twistd after the script is executed: log files would be owned by root instead of by the specified uid/gid. This is not what you asked, but I guess it's also a consequence of the "execute the script first" behavior of twistd.
If we are going to change this behavior, we should make twistd do something more correct, and optionally allow it to report startup errors to the console after it's forked, even if those errors don't necessarily crash it during startup. This isn't rocket science, inheriting file descriptors and delaying exit are all pretty easy.
When using twistd from a typical Linux init script, forking first would lead to the script reporting the startup was a success and after that the error message would be printed. Bye, Maarten