[hibernate-dev] ci.hibernate.org : announcing distributed cache for maven artifacts

Sanne Grinovero sanne at hibernate.org
Tue Jan 16 16:51:41 EST 2018 

On 16 January 2018 at 21:33, Steve Ebersole <steve at hibernate.org> wrote:
> well Gradle is used in CI environments all over the place, so it must work.
> But I think we need some different configurations in the Gradle command
> used.  For example, it is highly suggested that the Gradle daemon be
> disabled in CI but I'm not sure all of our jobs actually do that.  I'll look
> into that...

I wouldn't mind having the Gradle deamon always on, if it helps we
could even pre-load it with some tuned configuration.
The only drawback I see is to make it easy to upgrade Gradle version,
in case one needs, without having to go through server configuration
scripts.

We need strict isolation about writes in the cache though; for now
I'll disable it, not least for the concerns that Yoann and Gunnar
pointed out, then we can experiment with cool ideas more carefully.

Funny, one would expect to know by know about the perils of a
distributed cache :)


>
> On Tue, Jan 16, 2018 at 3:30 PM Sanne Grinovero <sanne at hibernate.org> wrote:
>>
>> Yes I did it for Gradle too, sorry. The `/efs-maven-artifacts` is the
>> guilty mount point.
>>
>> I don't know any quick solutions for the various concerns you all
>> raised, so I'll roll this back tonight.
>>
>> It's good to know that it's not too hard to have a shared FS between
>> these machines; needs better planning though.
>>
>> Thanks,
>> Sanne
>>
>> On 16 January 2018 at 19:41, Steve Ebersole <steve at hibernate.org> wrote:
>> > Did you happen to do the same for Gradle caches?
>> >
>> > Some jobs are failing:
>> >
>> >
>> > * What went wrong:
>> > Could not resolve all dependencies for configuration
>> > ':buildSrc:runtimeClasspath'.
>> >> Timeout waiting to lock artifact cache
>> >> (/efs-maven-artifacts/.gradle/caches/modules-2). It is currently in use
>> >> by
>> >> another Gradle instance.
>> >   Owner PID: 1423
>> >   Our PID: 10249
>> >   Owner Operation: resolve configuration ':classpath'
>> >   Our operation:
>> >   Lock file:
>> > /efs-maven-artifacts/.gradle/caches/modules-2/modules-2.lock
>> >
>> >
>> >
>> > On Mon, Jan 15, 2018 at 5:06 AM Yoann Rodiere <yoann at hibernate.org>
>> > wrote:
>> >>
>> >> > We should reconfigure those to not "install" - that's actually a bad
>> >> > habit, legacy from Maven 2 times - people nowadays recommend using
>> >> > "mvn clean verify", especially on CI environments.
>> >>
>> >> I could not agree more, that would be cleaner, but that's not possible.
>> >> And
>> >> believe me, I tried hard. Last time I checked, some of the plugins we
>> >> use
>> >> with dynamic dependency resolution would ignore the artifacts being
>> >> built,
>> >> and would always fetch the artifacts from the Maven repos (for
>> >> SNAPSHOTs,
>> >> they would end up using nightlies).
>> >> I'm not talking about when we use standard maven markup to declare
>> >> dependencies, but when the plugin itself has to fetch dependencies
>> >> "dynamically", which happens when we setup a WildFly server with our
>> >> own
>> >> modules in particular. See maven-dependency-plugin's "artifactItems"
>> >> configuration.
>> >>
>> >>
>> >>
>> >> On Mon, 15 Jan 2018 at 11:29 Sanne Grinovero <sanne at hibernate.org>
>> >> wrote:
>> >>
>> >> > On 15 January 2018 at 08:42, Yoann Rodiere <yoann at hibernate.org>
>> >> > wrote:
>> >> > > Thanks Sanne !
>> >> > >
>> >> > > I have one question...
>> >> > >
>> >> > >> Please never rely on this as "storage": it's just meant as cache
>> >> > >> and
>> >> > >> we reserve the right to wipe it all out at any time.
>> >> > >
>> >> > > I gather you say that so that we don't try to "release" artifacts
>> >> > > into
>> >> > this
>> >> > > cache? But temporary storage for the duration of one build will
>> >> > > still
>> >> > > be
>> >> > > safe?
>> >> > >
>> >> > > Because our builds obviously rely on the local repository for
>> >> > > short-term
>> >> > > storage (for the duration of the build). For example the
>> >> > > dependencies
>> >> > > are
>> >> > > only checked and downloaded if necessary at the beginning of the
>> >> > > build,
>> >> > and
>> >> > > then are expected to exist in the local repository until the build
>> >> > > stops.
>> >> > > Another example: our WildFly modules are first built and installed
>> >> > > in
>> >> > > the
>> >> > > "modules" subproject, and later "fetched" from the local repository
>> >> > > in
>> >> > the
>> >> > > "integrationtest/wildfly" subproject.
>> >> > >
>> >> > > If we were to clear the cache during a build, things would probably
>> >> > > go
>> >> > > wrong. Worse, if two parallel builds were to install the same
>> >> > > artifacts
>> >> > > (e.g. hibernate-search-engine version 5.9.0-SNAPSHOT), we would run
>> >> > > the
>> >> > risk
>> >> > > of testing the wrong "version" of this artifact in one of the
>> >> > > builds...
>> >> >
>> >> > SNAPSHOT being installed are indeed a problem, e.g the PR testing
>> >> > jobs
>> >> > could conflict with the regular master jobs.
>> >> > We should reconfigure those to not "install" - that's actually a bad
>> >> > habit, legacy from Maven 2 times - people nowadays recommend using
>> >> > "mvn clean verify", especially on CI environments.
>> >> >
>> >> > I agree about the perils of clearing the cache during in-progress
>> >> > builds
>> >> > too.
>> >> >
>> >> > I just meant to warn that we don't have any backup plan in place, and
>> >> > I do plan to just wipe the whole thing occasionally:
>> >> >  - when we have any direct need, e.g. currupted downloads
>> >> >  - when it gets too large
>> >> >  - if it gets too expensive
>> >> >  - regularly, just to "practice" that everything works with an empty
>> >> > cache
>> >> >
>> >> > Also our "disaster recovery" plan to rebuild all infrastructure will
>> >> > always assume it's ok to reboot with having this file system empty.
>> >> >
>> >> > Thanks,
>> >> > Sanne
>> >> >
>> >> > >
>> >> > >
>> >> > > On Sun, 14 Jan 2018 at 01:18 Sanne Grinovero <sanne at hibernate.org>
>> >> > wrote:
>> >> > >>
>> >> > >> Hi all,
>> >> > >>
>> >> > >> while the new build machines are fast, some of you pointed out
>> >> > >> we're
>> >> > >> now spending a relative high amount of time downloading maven
>> >> > >> dependencies, this problem being compounded by the fact we "nuke"
>> >> > >> idle
>> >> > >> slaves shortly after they become idle.
>> >> > >>
>> >> > >> I just spent the day testing a distributed file system, and it's
>> >> > >> now
>> >> > >> running in "production".
>> >> > >> It's used exclusively to store the Gradle and Maven caches. This
>> >> > >> is
>> >> > >> stateful and independent from the lifecycle of individual slave
>> >> > >> nodes.
>> >> > >>
>> >> > >> Unfortunately this solution is not viable for Docker images, so
>> >> > >> while
>> >> > >> I experimented with the idea I backed off from moving the docker
>> >> > >> storage graph to a similar device. Please don't waste time trying
>> >> > >> that
>> >> > >> w/o carefully reading the Docker documentation or talking with me
>> >> > >> :)
>> >> > >> Also, beyond correctness of storage semantics, it's likely far
>> >> > >> less
>> >> > >> efficient for Docker.
>> >> > >>
>> >> > >> To learn more about our new cache:
>> >> > >>  -
>> >> > >>
>> >> >
>> >> >
>> >> > https://github.com/hibernate/ci.hibernate.org/commit/dc6e0a4bd09fb3ae6347081243b4fb796a219f90
>> >> > >>  - https://docs.aws.amazon.com/efs/latest/ug/how-it-works.html
>> >> > >>
>> >> > >> I'd add that - because of other IO tuning in place - writes might
>> >> > >> appear out of order to other nodes, and conflicts are not handled.
>> >> > >> Shouldn't be a problem since snapshots now have timestamps, but
>> >> > >> this
>> >> > >> might be something to keep in mind.
>> >> > >>
>> >> > >> N.B.
>> >> > >> Please never rely on this as "storage": it's just meant as cache
>> >> > >> and
>> >> > >> we reserve the right to wipe it all out at any time.
>> >> > >>
>> >> > >> Thanks,
>> >> > >> Sanne
>> >> > >> _______________________________________________
>> >> > >> hibernate-dev mailing list
>> >> > >> hibernate-dev at lists.jboss.org
>> >> > >> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>> >> > >
>> >> > >
>> >> > >
>> >> > > --
>> >> > > Yoann Rodiere
>> >> > > yoann at hibernate.org / yrodiere at redhat.com
>> >> > > Software Engineer
>> >> > > Hibernate NoORM team
>> >> >
>> >>
>> >>
>> >> --
>> >> Yoann Rodiere
>> >> yoann at hibernate.org / yrodiere at redhat.com
>> >> Software Engineer
>> >> Hibernate NoORM team
>> >> _______________________________________________
>> >> hibernate-dev mailing list
>> >> hibernate-dev at lists.jboss.org
>> >> https://lists.jboss.org/mailman/listinfo/hibernate-dev

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