[ZODB-Dev] ZEO test failures

[Marius Gedminas]

On Tue, Mar 19, 2013 at 02:04:05PM +0200, Albertas Agejevas wrote:
> ZEO master has two failing tests (client_has_newer_data_than_server

Tres tried to fix it, and then I tried to fix it.  Winbot still finds
fault with our fixes :-(

> and zeo-fan-out.test).

This is a bit non-deterministic.  There's another similar
nondeterministic failure in new_addr.test.

> Looks like master is not tested by any automated
> systems.

We now have http://winbot.zope.org/builders/ZEO_py_265_32 and
https://travis-ci.org/zopefoundation/ZEO

> Also, I've mostly made the py3 branch to pass tests on Python 3.3,
> there are the two failures that also appear on master,

I've also seen failures in checkReadOnlyFallbackReadOnlyServer,
checkReconnectSwitch, checkQuickVerificationWith2Clients, and
checkExceptionLogsAtError on Python 3.x.

These don't appear to be reproducible in isolation.  I'm not sure if
they're nondeterministic failures, or if some other test leaves unclean
global state that trips up later tests.

> and one that
> appears a genuine problem (checkConcurrentLargeUpdates).  In this test
> there are three threads showering a BTree with updates with commits in
> batches of ~50.  Looks like some of the commits disappear.

It looks to me like a bug in conflict resolution.  I looked at the test
DB with zodbbrowser: its not that commits disappear but rather new
commits (made by a different thread) revert some OOBTree keys to older values.

Scary.

> Could someone more familiar with ZEO look into these failures?

I'm not familiar with ZEO.

Marius Gedminas
-- 
"Nobody will ever need more than 640k RAM!"
                                -- Bill Gates, 1981
"Windows 95 needs at least 8 MB RAM."
                                -- Bill Gates, 1996
"Nobody will ever need Windows 95."
                                -- logical conclusion
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