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From Nikolay Izhikov <nizhi...@apache.org>
Subject Re: Critical worker threads liveness checking drawbacks
Date Wed, 19 Dec 2018 10:24:04 GMT
Hello, Alexey.

No, we don't include this ticket to 2.7.
Should we?

ср, 19 дек. 2018 г. в 12:55, Alexey Goncharuk <alexey.goncharuk@gmail.com>:

> Folks, why did not we include IGNITE-10003 to ignite-2.7 release scope?
> This causes an Ignite node to be stopped by default when checkpoint read
> lock acquire times out. I expect a lot of Ignite 2.7 users will be affected
> by this mistake.
>
> We should at least update the documentation and make users aware of a
> workaround.
>
> чт, 25 окт. 2018 г. в 16:35, Alexey Goncharuk <alexey.goncharuk@gmail.com
> >:
>
> > Andrey,
> >
> > I still see that checkpoint read lock acquisition raises a
> CRITICAL_ERROR,
> > which by default will shut down local node. As far as I remember, we
> > decided that by default thread timeout should not trigger node failure.
> > Now, however, it does, because we ignore SYSTEM_WORKER_BLOCKED events in
> > default configuration.
> >
> > Should we introduce another critical failure type
> > CHECKPOINT_READ_LOCK_BLOCKED or use SYSTEM_WORKER_BLOCKED for checkpoint
> > read lock acquire failure?
> >
> > --AG
> >
> > пт, 12 окт. 2018 г. в 8:29, Andrey Kuznetsov <stkuzma@gmail.com>:
> >
> >> Igniters,
> >>
> >> Now I spot blocking / long-running code arising from
> >> {{GridDhtPartitionsExchangeFuture#init}} calls in partition-exchanger
> >> thread, see [1]. Ideally, all blocking operations along all possible
> code
> >> paths should be guarded implicitly from critical failure detector to
> avoid
> >> the thread from being considered blocked. There is a pull request [2]
> that
> >> provides shallow solution. I didn't change code outside
> >> {{GridDhtPartitionsExchangeFuture}}, otherwise it could be broken by any
> >> upcoming change. Also, I didn't touch the code runnable by threads other
> >> than partition-exchanger. So I have a number of guarded sections that
> are
> >> wider than they could be, and this potentially hides issues from failure
> >> detector. Does this PR make sense? Or maybe it's better to exclude
> >> partition-exchanger from critical threads registry at all?
> >>
> >> [1] https://issues.apache.org/jira/browse/IGNITE-9710
> >> [2] https://github.com/apache/ignite/pull/4962
> >>
> >>
> >> пт, 28 сент. 2018 г. в 18:56, Maxim Muzafarov <maxmuzaf@gmail.com>:
> >>
> >> > Andrey, Andrey
> >> >
> >> > > Thanks for being attentive! It's definitely a typo. Could you please
> >> > create
> >> > > an issue?
> >> >
> >> > I've created an issue [1] and prepared PR [2].
> >> > Please, review this change.
> >> >
> >> > [1] https://issues.apache.org/jira/browse/IGNITE-9723
> >> > [2] https://github.com/apache/ignite/pull/4862
> >> >
> >> > On Fri, 28 Sep 2018 at 16:58 Yakov Zhdanov <yzhdanov@apache.org>
> wrote:
> >> >
> >> > > Config option + mbean access. Does that make sense?
> >> > >
> >> > > Yakov
> >> > >
> >> > > On Fri, Sep 28, 2018, 17:17 Vladimir Ozerov <vozerov@gridgain.com>
> >> > wrote:
> >> > >
> >> > > > Then it should be config option.
> >> > > >
> >> > > > пт, 28 сент. 2018 г. в 13:15, Andrey Gura <agura@apache.org>:
> >> > > >
> >> > > > > Guys,
> >> > > > >
> >> > > > > why we need both config option and system property? I believe
> one
> >> way
> >> > > is
> >> > > > > enough.
> >> > > > > On Fri, Sep 28, 2018 at 12:38 PM Nikolay Izhikov <
> >> > nizhikov@apache.org>
> >> > > > > wrote:
> >> > > > > >
> >> > > > > > Ticket created -
> >> https://issues.apache.org/jira/browse/IGNITE-9737
> >> > > > > >
> >> > > > > > Fixed version is 2.7.
> >> > > > > >
> >> > > > > > В Пт, 28/09/2018 в 11:41 +0300, Alexey Goncharuk пишет:
> >> > > > > > > Nikolay, I agree, a user should be able to disable both
> thread
> >> > > > liveness
> >> > > > > > > check and checkpoint read lock timeout check from config
> and a
> >> > > system
> >> > > > > > > property.
> >> > > > > > >
> >> > > > > > > пт, 28 сент. 2018 г. в 11:30, Nikolay Izhikov <
> >> > nizhikov@apache.org
> >> > > >:
> >> > > > > > >
> >> > > > > > > > Hello, Igniters.
> >> > > > > > > >
> >> > > > > > > > I found that this feature can't be disabled from config.
> >> > > > > > > > The only way to disable it is from JMX bean.
> >> > > > > > > >
> >> > > > > > > > I think it very dangerous: If we have some corner case or
> a
> >> bug
> >> > > in
> >> > > > > this
> >> > > > > > > > Watch Dog it can make Ignite unusable.
> >> > > > > > > > I propose to implement possibility to disable this feature
> >> > both -
> >> > > > > from
> >> > > > > > > > config and from JVM options.
> >> > > > > > > >
> >> > > > > > > > What do you think?
> >> > > > > > > >
> >> > > > > > > > В Чт, 27/09/2018 в 16:14 +0300, Andrey Kuznetsov пишет:
> >> > > > > > > > > Maxim,
> >> > > > > > > > >
> >> > > > > > > > > Thanks for being attentive! It's definitely a typo.
> Could
> >> you
> >> > > > > please
> >> > > > > > > >
> >> > > > > > > > create
> >> > > > > > > > > an issue?
> >> > > > > > > > >
> >> > > > > > > > > чт, 27 сент. 2018 г. в 16:00, Maxim Muzafarov <
> >> > > > maxmuzaf@gmail.com
> >> > > > > >:
> >> > > > > > > > >
> >> > > > > > > > > > Folks,
> >> > > > > > > > > >
> >> > > > > > > > > > I've found in `GridCachePartitionExchangeManager:2684`
> >> [1]
> >> > > > > (master
> >> > > > > > > >
> >> > > > > > > > branch)
> >> > > > > > > > > > exchange future wrapped
> >> > > > > > > > > > with double `blockingSectionEnd` method. Is it
> correct?
> >> I
> >> > > just
> >> > > > > want to
> >> > > > > > > > > > understand this change and
> >> > > > > > > > > > how should I use this in the future.
> >> > > > > > > > > >
> >> > > > > > > > > > Should I file a new issue to fix this? I think here
> >> > > > > > > >
> >> > > > > > > > `blockingSectionBegin`
> >> > > > > > > > > > method should be used.
> >> > > > > > > > > >
> >> > > > > > > > > > -------------
> >> > > > > > > > > > blockingSectionEnd();
> >> > > > > > > > > >
> >> > > > > > > > > > try {
> >> > > > > > > > > >     resVer = exchFut.get(exchTimeout,
> >> > TimeUnit.MILLISECONDS);
> >> > > > > > > > > > } finally {
> >> > > > > > > > > >     blockingSectionEnd();
> >> > > > > > > > > > }
> >> > > > > > > > > >
> >> > > > > > > > > >
> >> > > > > > > > > > [1]
> >> > > > > > > > > >
> >> > > > > > > > > >
> >> > > > > > > >
> >> > > > > > > >
> >> > > > >
> >> > > >
> >> > >
> >> >
> >>
> https://github.com/apache/ignite/blob/master/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/GridCachePartitionExchangeManager.java#L2684
> >> > > > > > > > > >
> >> > > > > > > > > > On Wed, 26 Sep 2018 at 22:47 Vyacheslav Daradur <
> >> > > > > daradurvs@gmail.com>
> >> > > > > > > > > > wrote:
> >> > > > > > > > > >
> >> > > > > > > > > > > Andrey Gura, thank you for the answer!
> >> > > > > > > > > > >
> >> > > > > > > > > > > I agree that wrapping of 'init' method reduces the
> >> profit
> >> > > of
> >> > > > > watchdog
> >> > > > > > > > > > > service in case of PME worker, but in other cases,
> we
> >> > > should
> >> > > > > wrap all
> >> > > > > > > > > > > possible long sections on
> >> GridDhtPartitionExchangeFuture.
> >> > > For
> >> > > > > example
> >> > > > > > > > > > > 'onCacheChangeRequest' method or
> >> > > > > > > > > > > 'cctx.affinity().onCacheChangeRequest' inside
> because
> >> it
> >> > > may
> >> > > > > take
> >> > > > > > > > > > > significant time (reproducer attached).
> >> > > > > > > > > > >
> >> > > > > > > > > > > I only want to point out a possible issue which may
> >> allow
> >> > > to
> >> > > > > end-user
> >> > > > > > > > > > > halt the Ignite cluster accidentally.
> >> > > > > > > > > > >
> >> > > > > > > > > > > I'm sure that PME experts know how to fix this issue
> >> > > > properly.
> >> > > > > > > > > > > On Wed, Sep 26, 2018 at 10:28 PM Andrey Gura <
> >> > > > agura@apache.org
> >> > > > > >
> >> > > > > > > >
> >> > > > > > > > wrote:
> >> > > > > > > > > > > >
> >> > > > > > > > > > > > Vyacheslav,
> >> > > > > > > > > > > >
> >> > > > > > > > > > > > Exchange worker is strongly tied with
> >> > > > > > > > > > > > GridDhtPartitionExchangeFuture#init and it is ok.
> >> > > Exchange
> >> > > > > worker
> >> > > > > > > >
> >> > > > > > > > also
> >> > > > > > > > > > > > shouldn't be blocked for long time but in reality
> it
> >> > > > > happens.It
> >> > > > > > > >
> >> > > > > > > > also
> >> > > > > > > > > > > > means that your change doesn't make sense.
> >> > > > > > > > > > > >
> >> > > > > > > > > > > > What actually make sense it is identification of
> >> places
> >> > > > which
> >> > > > > > > > > > > > intentionally blocking. May be some places/actions
> >> > should
> >> > > > be
> >> > > > > > > >
> >> > > > > > > > braced by
> >> > > > > > > > > > > > blocking guards.
> >> > > > > > > > > > > >
> >> > > > > > > > > > > > If you have failing tests please make sure that
> your
> >> > > > > > > >
> >> > > > > > > > failureHandler is
> >> > > > > > > > > > > > NoOpFailureHandler or any other handler with
> >> > > > > ignoreFailureTypes =
> >> > > > > > > > > > > > [CRITICAL_WORKER_BLOCKED].
> >> > > > > > > > > > > >
> >> > > > > > > > > > > >
> >> > > > > > > > > > > > On Wed, Sep 26, 2018 at 9:43 PM Vyacheslav
> Daradur <
> >> > > > > > > > > >
> >> > > > > > > > > > daradurvs@gmail.com>
> >> > > > > > > > > > > wrote:
> >> > > > > > > > > > > > >
> >> > > > > > > > > > > > > Hi Igniters!
> >> > > > > > > > > > > > >
> >> > > > > > > > > > > > > Thank you for this important improvement!
> >> > > > > > > > > > > > >
> >> > > > > > > > > > > > > I've looked through implementation and noticed
> >> that
> >> > > > > > > > > > > > > GridDhtPartitionsExchangeFuture#init has not
> been
> >> > > wrapped
> >> > > > > in
> >> > > > > > > >
> >> > > > > > > > blocked
> >> > > > > > > > > > > > > section. This means it easy to halt the node in
> >> case
> >> > of
> >> > > > > > > >
> >> > > > > > > > longrunning
> >> > > > > > > > > > > > > actions during PME, for example when we create a
> >> > cache
> >> > > > with
> >> > > > > > > > > > > > > StoreFactrory which connect to 3rd party DB.
> >> > > > > > > > > > > > >
> >> > > > > > > > > > > > > I'm not sure that it is the right behavior.
> >> > > > > > > > > > > > >
> >> > > > > > > > > > > > > I filled the issue [1] and prepared the PR [2]
> >> with
> >> > > > > reproducer
> >> > > > > > > >
> >> > > > > > > > and
> >> > > > > > > > > > >
> >> > > > > > > > > > > possible fix.
> >> > > > > > > > > > > > >
> >> > > > > > > > > > > > > Andrey, could you please look at and confirm
> that
> >> it
> >> > > > makes
> >> > > > > sense?
> >> > > > > > > > > > > > >
> >> > > > > > > > > > > > > [1]
> >> > https://issues.apache.org/jira/browse/IGNITE-9710
> >> > > > > > > > > > > > > [2] https://github.com/apache/ignite/pull/4845
> >> > > > > > > > > > > > > On Mon, Sep 24, 2018 at 9:46 PM Andrey
> Kuznetsov <
> >> > > > > > > >
> >> > > > > > > > stkuzma@gmail.com>
> >> > > > > > > > > > >
> >> > > > > > > > > > > wrote:
> >> > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > Denis,
> >> > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > I've created the ticket [1] with short
> >> description
> >> > of
> >> > > > the
> >> > > > > > > > > > >
> >> > > > > > > > > > > functionality.
> >> > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > [1]
> >> > > https://issues.apache.org/jira/browse/IGNITE-9679
> >> > > > > > > > > > > > > >
> >> > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > пн, 24 сент. 2018 г. в 17:46, Denis Magda <
> >> > > > > dmagda@apache.org>:
> >> > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > Andrey K. and G.,
> >> > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > Thanks, do we have a documentation ticket
> >> > created?
> >> > > > > Prachi
> >> > > > > > > > > >
> >> > > > > > > > > > (copied)
> >> > > > > > > > > > > can help
> >> > > > > > > > > > > > > > > with the documentation.
> >> > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > --
> >> > > > > > > > > > > > > > > Denis
> >> > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > On Mon, Sep 24, 2018 at 5:51 AM Andrey Gura
> <
> >> > > > > > > >
> >> > > > > > > > agura@apache.org>
> >> > > > > > > > > > >
> >> > > > > > > > > > > wrote:
> >> > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > Andrey,
> >> > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > finally your change is merged to master
> >> branch.
> >> > > > > > > >
> >> > > > > > > > Congratulations
> >> > > > > > > > > > >
> >> > > > > > > > > > > and
> >> > > > > > > > > > > > > > > > thank you very much! :)
> >> > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > I think that the next step is feature that
> >> will
> >> > > > allow
> >> > > > > > > >
> >> > > > > > > > signal
> >> > > > > > > > > > >
> >> > > > > > > > > > > about
> >> > > > > > > > > > > > > > > > blocked threads to the monitoring tools
> via
> >> > > MXBean.
> >> > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > I hope you will continue development of
> this
> >> > > > feature
> >> > > > > and
> >> > > > > > > > > >
> >> > > > > > > > > > provide
> >> > > > > > > > > > > your
> >> > > > > > > > > > > > > > > > vision in new JIRA issue.
> >> > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > On Tue, Sep 11, 2018 at 6:54 PM Andrey
> >> > Kuznetsov
> >> > > <
> >> > > > > > > > > > >
> >> > > > > > > > > > > stkuzma@gmail.com>
> >> > > > > > > > > > > > > > > > wrote:
> >> > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > David, Maxim!
> >> > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > Thanks a lot for you ideas.
> >> Unfortunately, I
> >> > > > can't
> >> > > > > adopt
> >> > > > > > > >
> >> > > > > > > > all
> >> > > > > > > > > > >
> >> > > > > > > > > > > of them
> >> > > > > > > > > > > > > > > > right
> >> > > > > > > > > > > > > > > > > now: the scope is much broader than the
> >> scope
> >> > > of
> >> > > > > the
> >> > > > > > > >
> >> > > > > > > > change I
> >> > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > implement.
> >> > > > > > > > > > > > > > > > I
> >> > > > > > > > > > > > > > > > > have had a talk to a group of Ignite
> >> > commiters,
> >> > > > > and we
> >> > > > > > > >
> >> > > > > > > > agreed
> >> > > > > > > > > > >
> >> > > > > > > > > > > to
> >> > > > > > > > > > > > > > > complete
> >> > > > > > > > > > > > > > > > > the change as follows.
> >> > > > > > > > > > > > > > > > > - Blocking instructions in
> system-critical
> >> > > which
> >> > > > > may
> >> > > > > > > > > >
> >> > > > > > > > > > resonably
> >> > > > > > > > > > > last
> >> > > > > > > > > > > > > > > long
> >> > > > > > > > > > > > > > > > > should be explicitly excluded from the
> >> > > > monitoring.
> >> > > > > > > > > > > > > > > > > - Failure handlers should have a setting
> >> to
> >> > > > > suppress some
> >> > > > > > > > > > >
> >> > > > > > > > > > > failures on
> >> > > > > > > > > > > > > > > > > per-failure-type basis.
> >> > > > > > > > > > > > > > > > > According to this I have updated the
> >> > > > > implementation: [1]
> >> > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > [1]
> >> > https://github.com/apache/ignite/pull/4089
> >> > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > пн, 10 сент. 2018 г. в 22:35, David
> >> Harvey <
> >> > > > > > > > > > >
> >> > > > > > > > > > > syssoftsol@gmail.com>:
> >> > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > When I've done this before,I've needed
> >> to
> >> > > find
> >> > > > > the
> >> > > > > > > >
> >> > > > > > > > oldest
> >> > > > > > > > > > >
> >> > > > > > > > > > > thread,
> >> > > > > > > > > > > > > > > and
> >> > > > > > > > > > > > > > > > kill
> >> > > > > > > > > > > > > > > > > > the node running that.   From a
> language
> >> > > > > standpoint,
> >> > > > > > > > > >
> >> > > > > > > > > > Maxim's
> >> > > > > > > > > > > "without
> >> > > > > > > > > > > > > > > > > > progress" better than "heartbeat".
>  For
> >> > > > > example, what
> >> > > > > > > >
> >> > > > > > > > I'm
> >> > > > > > > > > > >
> >> > > > > > > > > > > most
> >> > > > > > > > > > > > > > > > interested
> >> > > > > > > > > > > > > > > > > > in on a distributed system is which
> >> thread
> >> > > > > started the
> >> > > > > > > >
> >> > > > > > > > work
> >> > > > > > > > > > >
> >> > > > > > > > > > > it has
> >> > > > > > > > > > > > > > > not
> >> > > > > > > > > > > > > > > > > > completed the earliest, and when did
> >> that
> >> > > > thread
> >> > > > > last
> >> > > > > > > >
> >> > > > > > > > make
> >> > > > > > > > > > >
> >> > > > > > > > > > > forward
> >> > > > > > > > > > > > > > > > > > process.     You don't want to kill a
> >> node
> >> > > > > because a
> >> > > > > > > >
> >> > > > > > > > thread
> >> > > > > > > > > > >
> >> > > > > > > > > > > is
> >> > > > > > > > > > > > > > > waiting
> >> > > > > > > > > > > > > > > > on a
> >> > > > > > > > > > > > > > > > > > lock held by a thread that went
> off-node
> >> > and
> >> > > > has
> >> > > > > not
> >> > > > > > > > > >
> >> > > > > > > > > > gotten a
> >> > > > > > > > > > > > > > > response.
> >> > > > > > > > > > > > > > > > > > If you don't understand the dependency
> >> > > > > relationships,
> >> > > > > > > >
> >> > > > > > > > you
> >> > > > > > > > > > >
> >> > > > > > > > > > > will make
> >> > > > > > > > > > > > > > > > > > incorrect recovery decisions.
> >> > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > On Mon, Sep 10, 2018 at 4:08 AM Maxim
> >> > > > Muzafarov <
> >> > > > > > > > > > >
> >> > > > > > > > > > > maxmuzaf@gmail.com>
> >> > > > > > > > > > > > > > > > > > wrote:
> >> > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > I think we should find exact answers
> >> to
> >> > > these
> >> > > > > > > >
> >> > > > > > > > questions:
> >> > > > > > > > > > > > > > > > > > >  1. What `critical` issue exactly
> is?
> >> > > > > > > > > > > > > > > > > > >  2. How can we find critical issues?
> >> > > > > > > > > > > > > > > > > > >  3. How can we handle critical
> issues?
> >> > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > First,
> >> > > > > > > > > > > > > > > > > > >  - Ignore uninterruptable actions
> >> (e.g.
> >> > > > > > > >
> >> > > > > > > > worker\service
> >> > > > > > > > > > >
> >> > > > > > > > > > > shutdown)
> >> > > > > > > > > > > > > > > > > > >  - Long I/O operations (should be a
> >> > > > > configurable
> >> > > > > > > >
> >> > > > > > > > timeout
> >> > > > > > > > > > >
> >> > > > > > > > > > > for each
> >> > > > > > > > > > > > > > > > type of
> >> > > > > > > > > > > > > > > > > > > usage)
> >> > > > > > > > > > > > > > > > > > >  - Infinite loops
> >> > > > > > > > > > > > > > > > > > >  - Stalled\deadlocked threads
> (and\or
> >> too
> >> > > > many
> >> > > > > parked
> >> > > > > > > > > > >
> >> > > > > > > > > > > threads,
> >> > > > > > > > > > > > > > > > exclude
> >> > > > > > > > > > > > > > > > > > I/O)
> >> > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > Second,
> >> > > > > > > > > > > > > > > > > > >  - The working queue is without
> >> progress
> >> > > > (e.g.
> >> > > > > disco,
> >> > > > > > > > > > >
> >> > > > > > > > > > > exchange
> >> > > > > > > > > > > > > > > > queues)
> >> > > > > > > > > > > > > > > > > > >  - Work hasn't been completed since
> >> the
> >> > > last
> >> > > > > > > >
> >> > > > > > > > heartbeat
> >> > > > > > > > > > >
> >> > > > > > > > > > > (checking
> >> > > > > > > > > > > > > > > > > > > milestones)
> >> > > > > > > > > > > > > > > > > > >  - Too many system resources used
> by a
> >> > > thread
> >> > > > > for the
> >> > > > > > > > > >
> >> > > > > > > > > > long
> >> > > > > > > > > > > period
> >> > > > > > > > > > > > > > > of
> >> > > > > > > > > > > > > > > > time
> >> > > > > > > > > > > > > > > > > > > (allocated memory, CPU)
> >> > > > > > > > > > > > > > > > > > >  - Timing fields associated with
> each
> >> > > thread
> >> > > > > status
> >> > > > > > > > > > >
> >> > > > > > > > > > > exceeded a
> >> > > > > > > > > > > > > > > > maximum
> >> > > > > > > > > > > > > > > > > > time
> >> > > > > > > > > > > > > > > > > > > limit.
> >> > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > Third (not too many options here),
> >> > > > > > > > > > > > > > > > > > >  - `log everything` should be the
> >> default
> >> > > > > behaviour
> >> > > > > > > >
> >> > > > > > > > in
> >> > > > > > > > > >
> >> > > > > > > > > > all
> >> > > > > > > > > > > these
> >> > > > > > > > > > > > > > > > cases,
> >> > > > > > > > > > > > > > > > > > > since it may be difficult to find
> the
> >> > cause
> >> > > > > after the
> >> > > > > > > > > > >
> >> > > > > > > > > > > restart.
> >> > > > > > > > > > > > > > > > > > >  - Wait some interval of time and
> kill
> >> > the
> >> > > > > hanging
> >> > > > > > > >
> >> > > > > > > > node
> >> > > > > > > > > > >
> >> > > > > > > > > > > (cluster
> >> > > > > > > > > > > > > > > > should
> >> > > > > > > > > > > > > > > > > > be
> >> > > > > > > > > > > > > > > > > > > configured stable enough)
> >> > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > Questions,
> >> > > > > > > > > > > > > > > > > > >  - Not sure, but can workers miss
> >> their
> >> > > > > heartbeat
> >> > > > > > > > > > >
> >> > > > > > > > > > > deadlines if CPU
> >> > > > > > > > > > > > > > > > loads
> >> > > > > > > > > > > > > > > > > > up
> >> > > > > > > > > > > > > > > > > > > to 80%-90%? Bursts of momentary
> >> overloads
> >> > > can
> >> > > > > be
> >> > > > > > > > > > > > > > > > > > >     expected behaviour as a normal
> >> part
> >> > of
> >> > > > > system
> >> > > > > > > > > > >
> >> > > > > > > > > > > operations.
> >> > > > > > > > > > > > > > > > > > >  - Why do we decide that critical
> >> thread
> >> > > > should
> >> > > > > > > >
> >> > > > > > > > monitor
> >> > > > > > > > > > >
> >> > > > > > > > > > > each other?
> >> > > > > > > > > > > > > > > > For
> >> > > > > > > > > > > > > > > > > > > instance, if all the tasks were
> >> blocked
> >> > and
> >> > > > > unable to
> >> > > > > > > > > >
> >> > > > > > > > > > run,
> >> > > > > > > > > > > > > > > > > > >     node reset would never occur. As
> >> for
> >> > > me,
> >> > > > a
> >> > > > > better
> >> > > > > > > > > > >
> >> > > > > > > > > > > solution is
> >> > > > > > > > > > > > > > > to
> >> > > > > > > > > > > > > > > > use
> >> > > > > > > > > > > > > > > > > > a
> >> > > > > > > > > > > > > > > > > > > separate monitor thread or pool
> (maybe
> >> > both
> >> > > > > with
> >> > > > > > > >
> >> > > > > > > > software
> >> > > > > > > > > > > > > > > > > > >     and hardware checks) that not
> only
> >> > > checks
> >> > > > > > > >
> >> > > > > > > > heartbeats
> >> > > > > > > > > > >
> >> > > > > > > > > > > but
> >> > > > > > > > > > > > > > > > monitors the
> >> > > > > > > > > > > > > > > > > > > other system as well.
> >> > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > On Mon, 10 Sep 2018 at 00:07 David
> >> > Harvey <
> >> > > > > > > > > > >
> >> > > > > > > > > > > syssoftsol@gmail.com>
> >> > > > > > > > > > > > > > > > wrote:
> >> > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > It would be safer to restart the
> >> entire
> >> > > > > cluster
> >> > > > > > > >
> >> > > > > > > > than to
> >> > > > > > > > > > >
> >> > > > > > > > > > > remove
> >> > > > > > > > > > > > > > > the
> >> > > > > > > > > > > > > > > > last
> >> > > > > > > > > > > > > > > > > > > > node for a cache that should be
> >> > > redundant.
> >> > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > On Sun, Sep 9, 2018, 4:00 PM
> Andrey
> >> > Gura
> >> > > <
> >> > > > > > > > > > >
> >> > > > > > > > > > > agura@apache.org>
> >> > > > > > > > > > > > > > > wrote:
> >> > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > > Hi,
> >> > > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > > I agree with Yakov that we can
> >> > provide
> >> > > > some
> >> > > > > > > >
> >> > > > > > > > option
> >> > > > > > > > > > >
> >> > > > > > > > > > > that manage
> >> > > > > > > > > > > > > > > > worker
> >> > > > > > > > > > > > > > > > > > > > > liveness checker behavior in
> case
> >> of
> >> > > > > observing
> >> > > > > > > >
> >> > > > > > > > that
> >> > > > > > > > > > >
> >> > > > > > > > > > > some worker
> >> > > > > > > > > > > > > > > > is
> >> > > > > > > > > > > > > > > > > > > > > blocked too long.
> >> > > > > > > > > > > > > > > > > > > > > At least it will  some
> workaround
> >> for
> >> > > > > cases when
> >> > > > > > > >
> >> > > > > > > > node
> >> > > > > > > > > > >
> >> > > > > > > > > > > fails is
> >> > > > > > > > > > > > > > > > too
> >> > > > > > > > > > > > > > > > > > > > > annoying.
> >> > > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > > Backups count threshold sounds
> >> good
> >> > > but I
> >> > > > > don't
> >> > > > > > > > > > >
> >> > > > > > > > > > > understand how
> >> > > > > > > > > > > > > > > it
> >> > > > > > > > > > > > > > > > > > will
> >> > > > > > > > > > > > > > > > > > > > > help in case of cluster hanging.
> >> > > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > > The simplest solution here is
> >> alert
> >> > in
> >> > > > > cases of
> >> > > > > > > > > > >
> >> > > > > > > > > > > blocking of
> >> > > > > > > > > > > > > > > some
> >> > > > > > > > > > > > > > > > > > > > > critical worker (we can improve
> >> > > > > WorkersRegistry
> >> > > > > > > >
> >> > > > > > > > for
> >> > > > > > > > > > >
> >> > > > > > > > > > > this
> >> > > > > > > > > > > > > > > purpose
> >> > > > > > > > > > > > > > > > and
> >> > > > > > > > > > > > > > > > > > > > > expose list of blocked workers)
> >> and
> >> > > > > optionally
> >> > > > > > > >
> >> > > > > > > > call
> >> > > > > > > > > > >
> >> > > > > > > > > > > system
> >> > > > > > > > > > > > > > > > configured
> >> > > > > > > > > > > > > > > > > > > > > failure processor. BTW, failure
> >> > > processor
> >> > > > > can be
> >> > > > > > > > > > >
> >> > > > > > > > > > > extended in
> >> > > > > > > > > > > > > > > > order to
> >> > > > > > > > > > > > > > > > > > > > > perform any checks (e.g. backup
> >> > count)
> >> > > > and
> >> > > > > decide
> >> > > > > > > > > > >
> >> > > > > > > > > > > whether it
> >> > > > > > > > > > > > > > > > should
> >> > > > > > > > > > > > > > > > > > > > > stop node or not.
> >> > > > > > > > > > > > > > > > > > > > > On Sat, Sep 8, 2018 at 3:42 PM
> >> Andrey
> >> > > > > Kuznetsov <
> >> > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > stkuzma@gmail.com>
> >> > > > > > > > > > > > > > > > > > > > wrote:
> >> > > > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > > > David, Yakov, I understand
> your
> >> > > fears.
> >> > > > > But
> >> > > > > > > >
> >> > > > > > > > liveness
> >> > > > > > > > > > >
> >> > > > > > > > > > > checks
> >> > > > > > > > > > > > > > > deal
> >> > > > > > > > > > > > > > > > > > with
> >> > > > > > > > > > > > > > > > > > > > > > _critical_ conditions, i.e.
> when
> >> > > such a
> >> > > > > > > >
> >> > > > > > > > condition
> >> > > > > > > > > >
> >> > > > > > > > > > is
> >> > > > > > > > > > > met we
> >> > > > > > > > > > > > > > > > > > conclude
> >> > > > > > > > > > > > > > > > > > > > the
> >> > > > > > > > > > > > > > > > > > > > > > node as totally broken, and
> >> there
> >> > is
> >> > > no
> >> > > > > sense
> >> > > > > > > >
> >> > > > > > > > to
> >> > > > > > > > > > >
> >> > > > > > > > > > > keep it
> >> > > > > > > > > > > > > > > alive
> >> > > > > > > > > > > > > > > > > > > > regardless
> >> > > > > > > > > > > > > > > > > > > > > > the data it contains. If we
> >> want to
> >> > > > give
> >> > > > > it a
> >> > > > > > > > > > >
> >> > > > > > > > > > > chance, then
> >> > > > > > > > > > > > > > > the
> >> > > > > > > > > > > > > > > > > > > > condition
> >> > > > > > > > > > > > > > > > > > > > > > (long fsync etc.) should not
> >> > > considered
> >> > > > > as
> >> > > > > > > >
> >> > > > > > > > critical
> >> > > > > > > > > > >
> >> > > > > > > > > > > at all.
> >> > > > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > > > сб, 8 сент. 2018 г. в 15:18,
> >> Yakov
> >> > > > > Zhdanov <
> >> > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > yzhdanov@apache.org>:
> >> > > > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > > > > Agree with David. We need to
> >> have
> >> > > an
> >> > > > > > > >
> >> > > > > > > > opporunity
> >> > > > > > > > > > >
> >> > > > > > > > > > > set backups
> >> > > > > > > > > > > > > > > > count
> >> > > > > > > > > > > > > > > > > > > > > threshold
> >> > > > > > > > > > > > > > > > > > > > > > > (at runtime also!) that will
> >> not
> >> > > > allow
> >> > > > > any
> >> > > > > > > > > > >
> >> > > > > > > > > > > automatic stop
> >> > > > > > > > > > > > > > > if
> >> > > > > > > > > > > > > > > > > > there
> >> > > > > > > > > > > > > > > > > > > > > will be
> >> > > > > > > > > > > > > > > > > > > > > > > a data loss. Andrey, what do
> >> you
> >> > > > think?
> >> > > > > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > > > > --Yakov
> >> > > > > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > > > > --
> >> > > > > > > > > > > > > > > > > > > > > > Best regards,
> >> > > > > > > > > > > > > > > > > > > > > >   Andrey Kuznetsov.
> >> > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > > > --
> >> > > > > > > > > > > > > > > > > > > --
> >> > > > > > > > > > > > > > > > > > > Maxim Muzafarov
> >> > > > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > > > > --
> >> > > > > > > > > > > > > > > > > Best regards,
> >> > > > > > > > > > > > > > > > >   Andrey Kuznetsov.
> >> > > > > > > > > > > > > >
> >> > > > > > > > > > > > > >
> >> > > > > > > > > > > > > > --
> >> > > > > > > > > > > > > > Best regards,
> >> > > > > > > > > > > > > >   Andrey Kuznetsov.
> >> > > > > > > > > > > > >
> >> > > > > > > > > > > > >
> >> > > > > > > > > > > > >
> >> > > > > > > > > > > > > --
> >> > > > > > > > > > > > > Best Regards, Vyacheslav D.
> >> > > > > > > > > > >
> >> > > > > > > > > > >
> >> > > > > > > > > > >
> >> > > > > > > > > > > --
> >> > > > > > > > > > > Best Regards, Vyacheslav D.
> >> > > > > > > > > > >
> >> > > > > > > > > >
> >> > > > > > > > > > --
> >> > > > > > > > > > --
> >> > > > > > > > > > Maxim Muzafarov
> >> > > > > > > > > >
> >> > > > > > > > >
> >> > > > > > > > >
> >> > > > >
> >> > > >
> >> > >
> >> > --
> >> > --
> >> > Maxim Muzafarov
> >> >
> >>
> >>
> >> --
> >> Best regards,
> >>   Andrey Kuznetsov.
> >>
> >
>

Mime
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