view roundup/cgi/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 91ab3e0ffcd0
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"""Exceptions for use in Roundup's web interface.
"""

__docformat__ = 'restructuredtext'

from roundup.exceptions import LoginError, Unauthorised  # noqa: F401

from roundup.anypy.html import html_escape

from roundup.exceptions import RoundupException

class RoundupCGIException(RoundupException):
    pass

class HTTPException(RoundupCGIException):
    pass


class Redirect(HTTPException):
    pass


class NotFound(HTTPException):
    pass


class NotModified(HTTPException):
    pass


class PreconditionFailed(HTTPException):
    pass


class DetectorError(RoundupException):
    """Raised when a detector throws an exception.
Contains details of the exception."""
    def __init__(self, subject, html, txt):
        self.subject = subject
        self.html = html
        self.txt = txt
        BaseException.__init__(self, subject + ' ' + txt)


class FormError(ValueError):
    """An 'expected' exception occurred during form parsing.

    That is, something we know can go wrong, and don't want to alarm the user
    with.

    We trap this at the user interface level and feed back a nice error to the
    user.

    """
    pass


class SendFile(RoundupException):
    """Send a file from the database."""


class SendStaticFile(RoundupException):
    """Send a static file from the instance html directory."""


class SeriousError(RoundupException):
    """Raised when we can't reasonably display an error message on a
    templated page.

    The exception value will be displayed in the error page, HTML
    escaped.
    """
    def __str__(self):
        return """
<html><head><title>Roundup issue tracker: An error has occurred</title>
 <link rel="stylesheet" type="text/css" href="@@file/style.css">
</head>
<body class="body" marginwidth="0" marginheight="0">
 <p class="error-message">%s</p>
</body></html>
""" % html_escape(self.args[0])

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

Roundup Issue Tracker: http://roundup-tracker.org/