view roundup/exceptions.py @ 6565:2c2dbfc332ba

Try to handle multiple connections better. The session database is a hot spot. When multiple requests (e.g. 20) come in at the same time session database contention can get great. The original code didn't retry session database access when the open failed. This resulted in errors at the client. The second pass delayed 0.01 seconds and retried. It was better but we still had multiple second stalls. I think the first request got in, everybody else backed up and then retried at the same time. Again they stepped on each other. With logging I would see many counters go all the way to low single digits or to -1 indicating falure. This pass uses randomint to generate delays from 0-.125 seconds in 5ms increments. This performs better in testing. I rarely saw a counter less than 13 (2 failed retries). Current logging starts after 6 failures and counts down until success or failure.
author John Rouillard <rouilj@ieee.org>
date Thu, 16 Dec 2021 20:02:00 -0500
parents c177e7128dc9
children e16b7d47fdb2
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"""Exceptions for use across all Roundup components.
"""

__docformat__ = 'restructuredtext'


class RoundupException(Exception):
    pass

class LoginError(RoundupException):
    pass


class Unauthorised(RoundupException):
    pass

class RejectBase(RoundupException):
    pass

class Reject(RejectBase):
    """An auditor may raise this exception when the current create or set
    operation should be stopped.

    It is up to the specific interface invoking the create or set to
    handle this exception sanely. For example:

    - mailgw will trap and ignore Reject for file attachments and messages
    - cgi will trap and present the exception in a nice format
    """
    pass


class RejectRaw(Reject):
    """
    Performs the same function as Reject, except HTML in the message is not
    escaped when displayed to the user.
    """
    pass


class UsageError(ValueError):
    pass

# vim: set filetype=python ts=4 sw=4 et si

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