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Re: [ovirt-devel] [VDSM][sampling] thread pool status and handling of stuck calls
by Saggi Mizrahi 10 Jul '14

10 Jul '14

The more I think about it the more it looks like it's purely a libvirt issue. As long as we can make calls that get stuck on D state we can't scale under stress. In any case, seems like having an interface like. libvirtConnectionPool.request(args, callback) Would be a better solution than a thread pool. It would queue up the request and call the callback once it's done. pseudo example: def collectStats(): def callback(resp): doStuff(resp) threading.Timer(4, collectStats) lcp.listAllDevices(callback) We could have the timer queue in a threadpool since it normally runs in the main thread but that is orthogonal to the libvirt connection issue. As for the thread pool itself. As long as it's more than one class it's too complicated. Things like: * Task Cancelling * Re-queuing (periodic operations) Shouldn't be part of the thread pool. Task should just be functions. If we need something with a state we could use the __call__() method to make an object look like a function. I also don't mind doing if hasattr(task, "run") or callable(task) to handle it using an "interface" Re-queuing could be done with the build it threading.Timer as in threading.Timer(4.5, threadpool.queue, args=(self,)) That way each operation is responsible for handing the details of rescheduling. Should we always wait X, should we wait X - timeItTookToCalculate. You could also do: threading.Timer(2, threadpool.queue, args=(self,)) threading.Timer(4, self.handleBeingLate) Which would handle not getting queued for a certain amount of time. Task cancelling can't be done in a generic manner. The most I think we could do is have threadpool.stop() check hassattr("stop", task) and call it. ----- Original Message ----- > From: "Francesco Romani" <fromani(a)redhat.com> > To: devel(a)ovirt.org > Sent: Friday, July 4, 2014 5:48:59 PM > Subject: [ovirt-devel] [VDSM][sampling] thread pool status and handling of stuck calls > > Hi, > > Nir has begun reviewing my draft patches about the thread pool and sampling > refactoring (thanks!), > and already suggested quite some improvements which I'd like to summarize > > Quick links to the ongoing discussion: > http://gerrit.ovirt.org/#/c/29191/8/lib/threadpool/worker.py,cm > http://gerrit.ovirt.org/#/c/29190/4/lib/threadpool/README.rst,cm > > Quick summary of the discussion on gerrit so far: > 1. extract the scheduling logic from the thread pool. Either add a separate > scheduler class > or let the sampling task reschedule themselves after a succesfull > completion. > In any way the concept of 'periodic task', and the added complexity, > isn't needed. > > 2. drop all the *queue classes I've added, thus making the package simpler. > They are no longer needed since we remove the concept of periodic task. > > 3. have per-task timeout, move the stuck task detection elsewhere, like in > the worker thread, ot > maybe better in the aforementioned scheduler. > If the scheduler finds that any task started in the former pass (or even > before!) > has not yet completed, there is no point in keeping this task alive and it > should be cancelled. > > 4. the sampling task (or maybe the scheduler) can be smarter and halting the > sample in presence of > not responding calls for a given VM, granted the VM reports its > 'health'/responsiveness. > > (Hopefully I haven't forgot anything big) > > In the draft currently published, I reluctantly added the *queue classes and > I agree the periodic > task implementation is messy, so I'll be very happy to drop them. > > However, a core question still holds: what to do in presence of the stuck > task? > > I think it is worth to discuss this topic on a medium friendlier than gerrit, > as it is the single > most important decision to make in the sampling refactoring. > > It all boils down to: > Should we just keep somewhere stuck threads and wait? Should we cancel stuck > tasks? > > A. Let's cancel the stuck tasks. > If we move toward a libvirt connection pool, and we give each worker thread > in the sampling pool > a separate libvirt connection, hopefully read-only, then we should be able to > cancel stuck task by > killing the worker's libvirt connection. We'll still need a (probably much > simpler) watchman/supervisor, > but no big deal here. > Libvirt allows to close a connection from a different thread. > I haven't actually tried to unstuck a blocked thread this way, but I have no > reason to believe it > will not work. > > B. Let's keep around blocked threads > The code as it is just leaves a blocked libvirt call and the worker thread > that carried it frozen. > The stuck worker thread can be replaced up to a cap of frozen threads. > In this worst case scenario, we end up with one (blocked!) thread per VM, as > it is today, and with > no sampling data. > > I believe that #A has some drawbacks which we risk to overlook, and on the > same time #B has some merits. > > Let me explain: > The hardest case is a call blocked in the kernel in D state. Libvirt has no > more room than VDSM > to unblock it; and libvirt itself *has* a pool of resources (threads in this > case) which can be depleted > by stuck calls. Actually, retrying to do a failed task may deplete their pool > even faster[1]. > > I'm not happy to just push this problem down the stack, as it looks to me > that we gain > very little by doing so. VDSM itself surely stays cleaner, but the > VDS/hypervisor hosts on the whole > improves just a bit: libvirt scales better, and that gives us some more room. > > On the other hand, by avoiding to reissue dangerous calls, I believe we make > better use of > the host resources in general. Actually, the point of keeping blocked thread > around is a side effect > of not reattempting blocked calls. Moreover, to keep the blocked thread > around has a significant > benefit: we can discover at the earliest moment when it is safe again to do > the blocked call, > because the blocked call itself returns and we can track this event! (and of > course drop the > now stale result). Otherwise, if we drop the connection, we'll lose this > event and we have no > more option that trying again and hoping for the best[2] > > I know the #B approach is not the cleanest, but I think it has slightly more > appeal, especially > on the libvirt depletion front. > > Thoughts and comments very welcome! > > +++ > > [1] They have extensions to management API to dinamically adjust their thread > pool and/or to cancel > tasks, but it is in the RHEL7.2 timeframe. > [2] A crazy idea would be to do something like > http://en.wikipedia.org/wiki/Exponential_backoff > which I'm not sure would be beneficial > > Bests and thanks, > > -- > Francesco Romani > RedHat Engineering Virtualization R & D > Phone: 8261328 > IRC: fromani > _______________________________________________ > Devel mailing list > Devel(a)ovirt.org > http://lists.ovirt.org/mailman/listinfo/devel >

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Docker containers for ovirt-engine
by Daniel Erez 10 Jul '14

10 Jul '14

Hi, I've created a couple of Docker images with a running ovirt-engine service and uploaded to the Docker registry [1]. Quite useful for quickly having a ready-to-use environment (tests, demos, etc) or to be used as a base image for building new Docker Images. Note that currently the container is not persistent by its nature, hence for saving changes, take use of the 'commit' functionality [2]. [1] https://registry.hub.docker.com/u/danielerez/ovirt-engine/ [2] https://docs.docker.com/reference/commandline/cli/#commit

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Re: [ovirt-devel] [vdsm] virt-v2v integration feature
by Sandro Bonazzola 10 Jul '14

10 Jul '14

Il 09/07/2014 20:26, Arik Hadas ha scritto: > Hi All, > > The proposed feature will introduce a new process of import virtual machines from external systems using virt-v2v in oVirt. > I've created a wiki page that contains initial thoughts and design for it: > http://www.ovirt.org/Features/virt-v2v_Integration > > You are more than welcome to share your thoughts and insights. Please use http://www.ovirt.org/Feature_template as template > > Thanks, > Arik > _______________________________________________ > vdsm-devel mailing list > vdsm-devel(a)lists.fedorahosted.org > https://lists.fedorahosted.org/mailman/listinfo/vdsm-devel > -- Sandro Bonazzola Better technology. Faster innovation. Powered by community collaboration. See how it works at redhat.com

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3.6 release in bugzilla
by Michal Skrivanek 10 Jul '14

10 Jul '14

can someone please add 3.6 to oVirt release in bugzilla? Thanks, michal

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oVirt 3.5 Test Day 1 Results - user defined Windows Sysprep file
by Vojtech Szocs 10 Jul '14

10 Jul '14

Hi, today I played with this feature [1]: - Win7 VM without custom Sysprep override in VM dialog - Win7 VM with custom Sysprep override in VM dialog - REST API call to check custom Sysprep override for VM [1] https://bugzilla.redhat.com/show_bug.cgi?id=1080002 It worked for me without any problems. Vojtech

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[QE][ACTION NEEDED] oVirt 3.4.3 RC status
by Sandro Bonazzola 10 Jul '14

10 Jul '14

Hi, We're going to start composing oVirt 3.4.3 RC tomorrow *2014-07-10 08:00 UTC* from 3.4 branch. A 3.4.3 branch will be created immediately after using the same hash of the build. The bug tracker [1] shows no blocking bugs for the release Bug 1096312 - log spam in vdsm: guest agents not heartbeating has been proposed for backport from 3.6 target on the bug tracker [1] There are still 28 bugs [2] targeted to 3.4.3. Excluding node and documentation bugs we still have 9 bugs [3] targeted to 3.4.3. Maintainers / Assignee: - Please add the bugs to the tracker if you think that 3.4.3 should not be released without them fixed. - Please update the target to any next release for bugs that won't be in 3.4.3: it will ease gathering the blocking bugs for next releases. - Please fill release notes, the page has been created here [4] - Please build packages before today *2014-07-09 15:00 UTC*. Community: - If you're testing oVirt 3.4 nightly snapshot, please add yourself to the test page [5] [1] bugzilla.redhat.com/1107968 [2] http://red.ht/1lBAw2R [3] http://red.ht/1ly9hfA [4] http://www.ovirt.org/OVirt_3.4.3_Release_Notes [5] http://www.ovirt.org/Testing/oVirt_3.4.3_Testing -- Sandro Bonazzola Better technology. Faster innovation. Powered by community collaboration. See how it works at redhat.com

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Update on ovirt-appliance and ovirt-node-iso for oVirt 3.5
by Fabian Deutsch 10 Jul '14

10 Jul '14

Hello, I just wanted to give a short update on the state of the ovirt-appliance and ovirt-node-iso for 3.5. ovirt-node is actually in a quite good shape. An iso is available with the ovirt-node-plugin-vdsm and -hosted-engine. Both based on ovirt-node from master, which will be branched off. The pain point is the automation. Ryan has actually gotten the Jenkins job back into place - good job! - so that at least the rpm packages are built. And could actually be included in the nighlies, Sandro. The automatic iso generation is still not working, due to several reasons (same as the last N months). The appliance generation is in a slightly better state than the ovirt-node-iso generation, but is still failing when it comes to automation. The automation is currently blocked by several issues which I tried to tackle together with David during the last week. The build automation of the appliance is actually getting most of my attention these days, as it is more likely to get the automation working. So we are not stable yet, but we are moving into the right direction. Greetings fabian

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Command/Query infrastructure changes in 3.5
by Oved Ourfali 10 Jul '14

10 Jul '14

Hi As part of 3.5 we did some changes in the command/query infrastructure that change the way they should be written. These changes and some usage examples are described in http://www.ovirt.org/Wiki/Engine_Command_changes This wiki page was written by Ravi and Yair. Please go over those, as it is relevant for everyone writing a new engine command/query. Thank you, Oved

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[URGENT][ACTION REQUIRED][vdsm] vdsm_3.4_create-rpms_merged failing on F19
by Sandro Bonazzola 09 Jul '14

09 Jul '14

Hi, VDSM from 3.4 branch is failing build on F19, see http://jenkins.ovirt.org/view/Publishers/job/vdsm_3.4_create-rpms_merged/la… Since 3.4.3 RC is scheduled for tomorrow, please fix this as soon as possible. Thanks -- Sandro Bonazzola Better technology. Faster innovation. Powered by community collaboration. See how it works at redhat.com

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[QE][ACTION NEEDED] oVirt 3.5.0 Second Beta status
by Sandro Bonazzola 09 Jul '14

09 Jul '14

Hi, We're going to compose oVirt 3.5.0 Second Beta on Mon *2014-07-21 08:00 UTC*. Maintainers: - Please be sure that 3.5 snapshot allow to create VMs before *2014-07-20 15:00 UTC* The bug tracker [1] shows the following proposed blockers to be reviewed: Bug ID Whiteboard Status Summary 1114994 infra NEW Cannot edit cluster after upgrade from version 3.4 to 3.5 because cpu type (Intel Haswell) does not match 1115044 infra POST Host stuck in "Unassinged" state when using jsonrpc and disconnection from pool failed 1115152 infra POST Cannot edit or create block storage doamin when using jsonrpc 1116009 infra POST sdk always raises a DisconnectedError trying to instantiate again after a previous failure 1060198 integration NEW [RFE] add support for Fedora 20 1073944 integration ASSIGNED Add log gathering for a new ovirt module (External scheduler) 1113974 integration POST Hostname validation during all-in-one setup 1113091 network POST VDSM trying to restore saved network rollback 1114057 storage NEW uploaded iso is not visible in the engine 1110305 virt POST BSOD - CLOCK_WATCHDOG_TIMEOUT_2 - Win 7SP1 guest, need to set hv_relaxed About Add log gathering for a new ovirt module (External scheduler), patch have been merged on upstream sos master branch. For Fedora >= 19 sos-3.1 package includes the fix. For EL 6 patches need to be backported to ovirt-log-collector. Feature freeze is now effective, and branch has been created. All new patches must be backported to 3.5 branch too. Features completed are marked in green on Features Status Table [2] There are still 422 bugs [3] targeted to 3.5.0. Excluding node and documentation bugs we still have 358 bugs [4] targeted to 3.5.0. Maintainers / Assignee: - Please remember to rebuild your packages before *2014-07-20 15:00* if needed, otherwise nightly snapshot will be taken. - Please be sure that 3.5 snapshot allow to create VMs before *2014-07-20 15:00 UTC* - If you find a blocker bug please remember to add it to the tracker [1] - Please start filling release notes, the page has been created here [5] - Please review and add test cases to oVirt 3.5 Second Test Day [6] Community: - Thanks for your participation in first test day! - You're welcome to join us testing next beta release and getting involved in oVirt Quality Assurance[7]! [1] http://bugzilla.redhat.com/1073943 [2] http://bit.ly/17qBn6F [3] http://red.ht/1pVEk7H [4] http://red.ht/1rLCJwF [5] http://www.ovirt.org/OVirt_3.5_Release_Notes [6] http://www.ovirt.org/OVirt_3.5_TestDay [7] http://www.ovirt.org/OVirt_Quality_Assurance Thanks, -- Sandro Bonazzola Better technology. Faster innovation. Powered by community collaboration. See how it works at redhat.com

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