psdiff.rst

Example psdiff.conf for celery (python3)

Celery (at least on python3) reorders its arguments -- probably because argv passes through a dictionary at some point -- before it hands them to the detached worker parent. That means that the psdiff output changes between celery restarts. This example /etc/psdiff.conf checks for those processes and sorts the output:

import re

class LocalFilteredProcessFormatter(
        FilteredProcessFormatter):
    # These processes have argv which is unordered. We sort $2.
    processes_with_unordered_argv = (
        '^([^ ]*python[^ ]* -m celery worker) (.*)',
    )

    processes_with_unordered_argv = tuple(
        re.compile(i) for i in processes_with_unordered_argv)

    def to_string(self, process, indent=0):
        # If the process cmdline matches anything in our
        # processes_with_unordered_argv list, we sort the second
        # matched group: that way we won't complain if the arguments
        # have a different order.
        for search in self.processes_with_unordered_argv:
            match = search.search(process.cmdline)
            if match:
                head, tail = match.groups()
                process.cmdline = ' '.join(
                    [head] + sorted(tail.split(' ')))
                break

        return super(LocalFilteredProcessFormatter, self).to_string(
            process, indent=indent)