Geoff,
Thanks I am well versed in unit testing but probably disagree on level
of use in a development cycle. Instead of writing a long email back
about testing theory, nondeterministic problems, highly connected
dependent systems blah blah I'll just say that most of the problems that
have plagued me have been because of interactions between translators,
kernel mods etc which unit testing doesn't really approach.
Since I'm running my setup as a storage farm it just doesn't matter to
me if there's a memory leak of if a server daemon crashes, I have cron
jobs that restart it and I barely take notice. True a regression testing
would get rid of the memory leak you hate but if they have to start from
the ground up I would rather encourage the dev team to add hotadd
upgrade and hotadd features. These things would keep my cluster going
even if there were catastrophic problems.
What I'm saying is that a good top down testing system is something we
can discuss here, spec out and perhaps create independently of the
development team. I think what most people want is a more stable product
and I think a top down approach will get it there faster than trying to
implement a given UT system from the bottom up. It will defiantly answer
the question "should I upgrade to this release?"
You mentioned that you had outlines some integration and function tests
previously, perhaps you could paste some into this thread so that we
could expand on them.
Thanks!
-Mickey Mazarick
Geoff Kassel wrote:
Hi Mickey,
Just so that we're all on the same page here - a regression test suite at
its most basic just has to include test cases (i.e. a set of inputs) that can
trigger a previously known fault in the code if that fault is present. (i.e
it can see if the code has 'regressed' into a condition where a fault is
present.)
What it's also taken to mean (and typically includes) is a set of tests
cases covering corner cases and normal modes of operation, as expressed in a
set of inputs to code paired with a set of expected outputs that may or may
not include error messages.
Test cases aimed at particular levels of the code have specific terminology
associated with those levels. At the lowest level, the method level, they're
called unit tests. At the module/API level - integration tests. At the
system/user interface level - system aka function aka functional aka
functionality tests.
When new functionality is introduced or a bug is patched, the regression
test suite (which in the case of unit tests is typically fully automated) is
run to see whether the expected behaviour occurs, and none of the old faults
recur.
A lot of the tests you've described fall into the category of function
tests - and from my background in automated testing, I know we need a bit
more than that to get the stability and reliability results we want. (Simply
because you cannot test every corner case within a project the size and
complexity of GlusterFS reliably from the command line.)
Basically, what GlusterFS needs is a fairly even coverage of test cases at
all the levels I've just mentioned.
What I want to see particularly - and what the devs stated nearly a year
ago was already in existence - is unit tests. Particularly the kind that can
be run automatically.
This is so that developers (inside the GlusterFS team or otherwise) can
hack on a piece of code to fix a bug or implement new functionality, then run
the unit tests to see that they (mostly likely) haven't caused a regression
with their new code.
(It's somewhat difficult for outsiders to write unit and integration tests,
because typically only the original developers have the in-depth knowledge of
the expected behaviour of the code in the low level detail required.)
Perhaps developed in parallel should be integration and function tests.
Tests like these (I've outlined elsewhere specifically what kind) would have
quite likely picked up the data corruption bugs before they made their way
into the first 2.0.x releases.
(Pretty much anyone familiar with the goal of the project can write
function tests, documenting in live code their expectations for how the
system should work.)
Long running stability and load tests like you've proposed are also kinds
of function tests, but without the narrowly defined inputs and outputs of
specific test cases. They're basically the equivalent of mine shaft
canaries - they signal the presence of race conditions, memory leaks, design
flaws, and other subtle issues, but often without specifics as to
what 'killed' the canary. Once the cause is found though, a new, more
specific test case can be added at the appropriate level.
(Useful, yes, but mostly as a starting point for more intensive QA
efforts.)
The POSIX compliance tests you mentioned are more traditional function
level tests - but I think the GlusterFS devs have wandered a little away from
full POSIX compliance on some points, so these tests may not be 100%
relevant.
(This is not necessarily a bad thing - the POSIX standard is apparently
ambiguous at times, and there is some wider community feeling that
improvements to the standard are overdue. And I'm not sure the POSIX standard
was ever written with massively scalable, plugable, distributed file systems
in mind, either :)
I hope my extremely long winded rant here :) has explained adequately what
I feel GlusterFS needs to have in a regression testing system.
Geoff.
On Tue, 7 Jul 2009, Mickey Mazarick wrote:
What kind of requirements does everyone see as necessary for a
regression test system?
Ultimately the best testing system would use the tracing translator and
be able to run tests and generate traces for any problems that occurs,
giving us something very concrete to provide the developers. That's a
few steps ahead however, initially we should start to outline some must
haves in terms of how a test setup is run. obviously we want something
we can run for many hours or days to test longterm stability, and it
would be nice if there was some central way to spin up new clients to
test reliability under a load.
For basic file operation tests I use the below:
An initial look would be to use some tools like
http://www.ntfs-3g.org/pjd-fstest.html
I've seen it mentioned before but it's a good start to test anything
posix. Here's a simple script that will download and build it if it's
missing, and run a test on a given mount point.
#!/bin/bash
if [ "$#" -lt 1 ]
then
echo "usage: $0 gluster_mount"
exit 65
fi
GLUSTER_MOUNT=$1
INSTALL_DIR="/usr"
if [ ! -d $INSTALL_DIR/fstest ]; then
cd $INSTALL_DIR
wget http://www.ntfs-3g.org/sw/qa/pjd-fstest-20080816.tgz
tar -xzf pjd-fstest-20080816.tgz
mv pjd-fstest-20080816 fstest
cd fstest
make
vi tests/conf
fi
cd $GLUSTER_MOUNT
prove -r $INSTALL_DIR/fstest/
Jacques Mattheij wrote:
hello Anand, Geoff & others,
This pretty much parallels my interaction with the team about a
year ago, lots of really good intentions but no actual follow up.
We agreed that an automated test suite was a must and that a
whole bunch of other things would have to be done to get
glusterfs out of the experimental stage and into production
grade.
It's a real pity because I still feel that glusterfs is one of the
major contenders to become *the* cluster file system.
A lot of community goodwill has been lost, I've kept myself
subscribed to this mailing list because I hoped that at some
point we'd move past this endless cat and mouse game with
stability issues but for some reason that never happend.
Anand, you have a very capable team of developers, you have
a once-in-a-lifetime opportunity to make this happen please
take Geoff's comments to hart and get serious about Q&A and
community support because that is the key to any successful
foss project. Fan that fire and you can't go wrong, lose the
community support and your project might as well be dead.
I realize this may come across as harsh but it is intended to
make it painfully obvious that the most staunch supporters
of glusterfs are getting discouraged and that is a loss no
serious project can afford.
Jacques
Geoff Kassel wrote:
Hi Anand,
If you look back through the list archives, no one other than me
replied to the original QA thread where I first posted my patches.
Nor to the Savannah patch tracker thread where I also posted my
patches. (Interesting how those trackers have been disabled now...)
It took me pressing the issue after discovering yet another bug
that we even started talking about my patches. So yes, my patches
were effectively ignored.
At the time, you did mention that the code the patches were to be
applied against was being reworked, in addition to your comments
about my code comments.
I explained the comments as being necessary to avoid the automated
tool flagging potential issues again on reuse of that tool - other
comments for future QA work. There was no follow up on that from you,
nor suggestion on how I might improve these comments to your standards.
I continued to supply patches in the Savannah tracker against the
latest stable 1.3 branch - which included some refactoring for your
reworked code, IIRC - for some time after that discussion. All of my
patches were in sync with the code from publically available 1.3
branch repository within days of a new TLA patchset.
None of these were adopted either.
I simply ran out of spare time to maintain this patchset, and I
got tired of pressing an issue (QA) that you and the dev team clearly
weren't interested in.
I don't have the kind of spare time needed to do the sort of
in-depth re-audit your code from scratch (as would be needed) in the
manner that I did back then. So I can't meet your request at this
time, sorry.
As I've suggested elsewhere, now that you apparently have the
resources for a stand-alone QA team - this team might want to at
least use the tools I've used to generate these patches - RATS and
FlawFinder.
That way you can generate the kind of QA work I was producing with
the kind of comment style you prefer.
The only way I can conceive of being able to help now is in
patching individual issues. However, I can really only feasibly do
that with my time constraints if I've got regression tests to make
sure I'm not inadvertently breaking other functionality.
Hence my continued requests for these.
Geoff.
On Tue, 7 Jul 2009, Anand Avati wrote:
I've also gone one better than just advice - I've given up
significant
portions of my limited spare time to audit and patch a
not-insignificant
portion of the GlusterFS code, in order to deal with the stability
issues
I and others were encountering. My patches were ignored, on the
grounds
that it contained otherwise unobtrusive comments which were quite
necessary to the audit.
Geoff, we really appreciate your efforts, both on the fronts of your
patch submissions and for voicing your opinions freely. We also
acknowledge the positive intentions behind this thread. As far as your
patch submissions are concerned, there is probably a misunderstanding.
Your patches were not ignored. We do value your efforts. The patches
which you submitted, even at the time of your submission were not
applicable to the codebase.
Patch 1 (in glusterfsd.c) -- this file was reworked and almost
rewritten from scratch to work as both client and server.
Patch 2 (glusterfs-fuse/src/glusterfs.c) -- this module was
reimplemented as a new translator (since a separate client was no more
needed).
Patch 3 (protocol.c) -- with the introduction of non blocking IO and
binary protocol, nothing of this file remained.
What I am hoping to convey is that, the reason your patches did not
make it to the repository was because it needed significant reworking
to even apply. I did indeed comment about code comments of the style
/* FlawFinder: */ but then, that definitely was _not_ the reason they
weren't included. Please understand that nothing was ignored
intentionally.
This being said, I can totally understand the efforts which you have
been putting to maintain patchsets by yourself and keeping them up to
date with the repository. I request you to resubmit them (with git
format-patch) against the HEAD of the repository.
Thanks,
Avati
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