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From kishore g <g.kish...@gmail.com>
Subject Re: keeping the master node up during bootstrap
Date Wed, 09 Apr 2014 19:41:41 GMT
Hi Vlad,

I have some questions. Can you join the IRC channel #apachehelix.

thanks,
Kishore G


On Wed, Apr 9, 2014 at 11:35 AM, vlad.gm@gmail.com <vlad.gm@gmail.com>wrote:

> Upon some further testing, it seems that the controller does not execute
> the events in the right sequence.
>
> Here are the results of some of my testing. Assume that we have a
> partition NEWPROFILE_5 with the ideal state:
>
>  "NEWPROFILE_5" : {
>
>       "pf1.apps-pf.dev.docker_12000" : "SLAVE",
>
>       "pf2.apps-pf.dev.docker_12000" : "MASTER"
>
>     }
>
> I boot the host pf1 and a few minutes later the host pf2. In the
> controller logs I see, when doing a grep for NEWPROFILE_5:
>
> 2014-04-08 17:04:35,309 (Thread-2) TaskAssignmentStage INFO: Sending
> Message 69b4eddf-ac5f-4726-9d6b-bac742ad082e to
> pf1.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:SLAVE to:MASTER
>
> 2014-04-08 17:27:08,187 (Thread-2) TaskAssignmentStage INFO: Sending
> Message a221b1ac-0807-425e-9062-6507e45b0bfb to
> pf1.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:OFFLINE
> to:BOOTSTRAP
>
> 2014-04-08 17:27:10,164 (Thread-2) TaskAssignmentStage INFO: Sending
> Message 73ed85fd-49c9-46a5-b262-687d612c7d06 to
> pf1.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:BOOTSTRAP to:SLAVE
>
> 2014-04-08 17:27:11,868 (Thread-2) TaskAssignmentStage INFO: Sending
> Message fb21aecc-68cf-4b9f-9718-aa6ed535c29d to
> pf1.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:SLAVE to:MASTER
>
> 2014-04-08 17:28:22,978 (Thread-2) TaskAssignmentStage INFO: Sending
> Message ea441d18-b1f3-4ceb-96a2-3262cab1dfbe to
> pf2.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:OFFLINE
> to:BOOTSTRAP
>
> 2014-04-08 17:28:22,978 (Thread-2) TaskAssignmentStage INFO: Sending
> Message f36b4d64-c790-413b-b9fa-915b9539d28c to
> pf1.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:MASTER to:SLAVE
>
> 2014-04-08 17:28:26,065 (Thread-2) TaskAssignmentStage INFO: Sending
> Message 201429e1-e810-4017-b3ef-fb5930ac2192 to
> pf2.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:BOOTSTRAP to:SLAVE
>
> 2014-04-08 17:28:28,238 (Thread-2) TaskAssignmentStage INFO: Sending
> Message 4a1fb64c-1063-4e49-a995-946d2dd25733 to
> pf2.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:SLAVE to:MASTER
>
> That is, the controller issues an offline->bootstrap command to pf-2, but
> then issues a master->slave command to of-1 before bringing pf-2 up as a
> slave as well (the last step before promotion to master). Since the
> bootstrap->slave that follows takes time, the system spends time without a
> master for the partition.
>
> The state model definition was:
> public static StateModelDefinition defineStateModel() {
> StateModelDefinition.Builder builder =
>  new StateModelDefinition.Builder(KVHelixDefinitions.STATE_MODEL_NAME);
> // Add states and their rank to indicate priority. Lower the rank higher
> the
>  // priority
> builder.addState(MASTER, 1);
> builder.addState(SLAVE, 2);
>  builder.addState(BOOTSTRAP, 3);
> builder.addState(OFFLINE);
> builder.addState(DROPPED);
>  // Set the initial state when the node starts
> builder.initialState(OFFLINE);
>
> // Add transitions between the states.
>  builder.addTransition(OFFLINE, BOOTSTRAP, 3);
> builder.addTransition(BOOTSTRAP, SLAVE, 2);
> builder.addTransition(SLAVE, MASTER, 1);
>  builder.addTransition(MASTER, SLAVE, 4);
> builder.addTransition(SLAVE, OFFLINE, 5);
> builder.addTransition(OFFLINE, DROPPED, 6);
>
> // set constraints on states.
> // static constraint
> builder.upperBound(MASTER, 1);
>  // dynamic constraint, R means it should be derived based on the
> replication
> // factor.
> builder.dynamicUpperBound(SLAVE, "R");
>
> StateModelDefinition statemodelDefinition = builder.build();
>
> assert(statemodelDefinition.isValid());
>
> return statemodelDefinition;
> }
>
> I have tried reversing the values of the transition priorities. In this
> case, the controller log file looked as follows:
>
> 2014-04-09 11:17:52,831 (Thread-2) TaskAssignmentStage INFO: Sending
> Message 2b29a319-c1c6-4042-b1ad-3e3c1b5092a7 to
> pf1.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:OFFLINE
> to:BOOTSTRAP
>
> 2014-04-09 11:17:55,672 (Thread-2) MessageGenerationStage INFO: Message
> hasn't been removed for pf1.apps-pf.dev.docker_12000 to transitNEWPROFILE_5
> to BOOTSTRAP, desiredState: MASTER
>
> 2014-04-09 11:17:57,047 (Thread-2) TaskAssignmentStage INFO: Sending
> Message b1ca701d-65f1-46b9-9ae4-286400d6d266 to
> pf1.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:BOOTSTRAP to:SLAVE
>
> 2014-04-09 11:17:58,888 (Thread-2) TaskAssignmentStage INFO: Sending
> Message fe10228f-8f5b-4133-964a-5f6c7e60b0e6 to
> pf1.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:SLAVE to:MASTER
>
> 2014-04-09 11:23:26,117 (Thread-2) TaskAssignmentStage INFO: Sending
> Message 6252a4e6-0ab8-490a-a51d-c47195c434b5 to
> pf1.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:MASTER to:SLAVE
>
> 2014-04-09 11:23:26,117 (Thread-2) TaskAssignmentStage INFO: Sending
> Message 18bbf028-cb51-4162-8226-a6564a121986 to
> pf2.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:OFFLINE
> to:BOOTSTRAP
>
> 2014-04-09 11:23:33,462 (Thread-2) MessageGenerationStage INFO: Message
> hasn't been removed for pf2.apps-pf.dev.docker_12000 to transitNEWPROFILE_5
> to BOOTSTRAP, desiredState: MASTER
>
> 2014-04-09 11:23:33,892 (Thread-2) TaskAssignmentStage INFO: Sending
> Message c7fc4983-9d71-4dc4-bfee-2ad69e4de411 to
> pf2.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:BOOTSTRAP to:SLAVE
>
> 2014-04-09 11:23:35,933 (Thread-2) TaskAssignmentStage INFO: Sending
> Message 75e715ed-3d53-4e39-b1e7-44695e4bfa03 to
> pf2.apps-pf.dev.docker_12000 transit NEWPROFILE_5|[] from:SLAVE to:MASTER
>
> That is, the transition for master->slave for pf1 was executed before
> taking any action on pf2, clearly the opposite of the right order.
>
>
> On Tue, Apr 8, 2014 at 2:19 PM, Kanak Biscuitwala <kanak.b@hotmail.com>wrote:
>
>>
>> Looks good, thanks for sharing!
>>
>> Kanak
>> ________________________________
>> > Date: Tue, 8 Apr 2014 14:08:28 -0700
>> > Subject: Re: keeping the master node up during bootstrap
>> > From: vlad.gm@gmail.com
>> > To: user@helix.apache.org
>> >
>> > My modified code looks like:
>> >
>> > /* Setup a Helix cluster for the KVStore */
>> > public static void setupCluster() {
>> > assert(cluster != null);
>> > clusterSetup.addCluster(cluster, true);
>> >
>> > а а а а ConstraintItemBuilder constraintItemBuilder = new
>> > ConstraintItemBuilder();
>> >
>> > а а а а constraintItemBuilder
>> > а а а а а а а а
>> > .addConstraintAttribute(ConstraintAttribute.MESSAGE_TYPE.toString(),
>> > "STATE_TRANSITION")
>> > а а а а а а а а
>> > .addConstraintAttribute(ConstraintAttribute.PARTITION.toString(), ".*")
>> > а а а а а а а а
>> > .addConstraintAttribute(ConstraintAttribute.CONSTRAINT_VALUE.toString(),
>> > "1");
>> >
>> > а а а а clusterSetup.getClusterManagementTool().setConstraint(cluster,
>> > а а а а а а а а ClusterConstraints.ConstraintType.MESSAGE_CONSTRAINT,
>> > а а а а а а а а "constraint1", constraintItemBuilder.build());
>> > а а }
>> >
>> > I will try to see whether it works in every situation.
>> >
>> > Regards,
>> > Vlad
>> >
>> >
>> > On Tue, Apr 8, 2014 at 8:59 AM, Vlad Balan
>> > <vlad.gm@gmail.com<mailto:vlad.gm@gmail.com>> wrote:
>> > Hi Kishore,
>> >
>> > I managed to implement the bootstrapping using the constraint and it
>> > appears to be running as expected. I will post my code shortly.
>> >
>> > Regards,
>> > Vlad
>> >
>> > On Apr 8, 2014, at 8:27 AM, kishore g
>> > <g.kishore@gmail.com<mailto:g.kishore@gmail.com>> wrote:
>> >
>> > Hi Vlad,
>> >
>> > Did you get a chance to play with the constraint.а I can write a sample
>> > code today to try this.
>> >
>> > Thanks,
>> > Kishore G
>> >
>> >
>> > On Thu, Apr 3, 2014 at 5:45 PM,
>> > vlad.gm@gmail.com<mailto:vlad.gm@gmail.com>
>> > <vlad.gm@gmail.com<mailto:vlad.gm@gmail.com>> wrote:
>> >
>> > Thank you Kanak and Kishore! I will try enforcing the per-partition
>> > constraint and let you know if somehow it does not work. I was looking
>> > at the throttling documentation, but somehow missed that a
>> > per-partition constraint was an option!
>> >
>> > Regards,
>> > Vlad
>> >
>> >
>> > On Thu, Apr 3, 2014 at 5:42 PM, kishore g
>> > <g.kishore@gmail.com<mailto:g.kishore@gmail.com>> wrote:
>> > Hi Vlad,
>> >
>> > You can try setting the transition priority order and a constraint that
>> > there should be only one transition per partition across the cluster.
>> >
>> > So the transition priority could be something like
>> >
>> > Slave-Master
>> > Offfline -> Bootstrap
>> > Bootstrap->Slave
>> > Slave->Master
>> >
>> > For the rest not sure if order matters.
>> >
>> > Also set the max transitions constraint to 1 per partition.
>> >
>> > The reason I put Slave-Master before Offline->Bootstrap is to ensure
>> > that availability is given more importance. For example if you have 3
>> > nodes, N1, N2, N3. N1 is Master, N2 is Slave, and N3 is down. If N1
>> > goes down and N3 comes up at the same time. We probably dont want to
>> > wait for N3 to bootstrap before promoting N2 to Master.
>> >
>> > I haven't tested this but assuming the constraints enforcement works,
>> > this should do the trick.
>> >
>> > Does this make sense? Let me know if this does not work, we can add a
>> > test case.
>> >
>> > thanks,
>> > Kishore G
>> >
>> >
>> >
>> >
>> >
>> >
>> > On Thu, Apr 3, 2014 at 4:57 PM,
>> > vlad.gm@gmail.com<mailto:vlad.gm@gmail.com>
>> > <vlad.gm@gmail.com<mailto:vlad.gm@gmail.com>> wrote:
>> >
>> > Dear all,
>> >
>> > I am trying to construct a state model with the following transition
>> diagram:
>> >
>> > OFFLINE -> BOOTSTRAPPING <---> SLAVE <-----> MASTER
>> > а а а а а<-----------------------------------
>> >
>> > That is, an offline mode can go into a bootstraping state, from the
>> > bootstrap state it can go into a slave state,
>> > from slave it can go from master, from master to slave and from slave
>> > it can go offline.
>> >
>> > Assume that if I have a partition with two nodes pf1 and pf2 and a
>> > partition partition_0 with the following ideal state:
>> >
>> > partition_0: pf2: MASTER pf1: SLAVE,
>> >
>> > and that currently pf1 is serving as a master. When pf2 boots, Helix
>> > will issue, almost simultaneously, two commands:
>> > for pf1: transition from MASTER to SLAVE
>> > for pf2: transition from BOOTSTRAPPING to SLAVE
>> >
>> > My understanding is that this happens since Helix is trying to execute
>> > as many commands in parallel and since the last state
>> > has pf2 as master. However, the transition from BOOTSTRAPPING to SLAVE
>> > for pf2 involves a long data copy step, so
>> > I would like to keep pf1 as a master in the meanwhile. I tried
>> > prioritizing the transition from BOOTSTRAPPING to SLAVE
>> > over the transition from MASTER to SLAVE, however Helix still issues
>> > them in parallel (as it should).
>> >
>> > I was wondering what my options would be in order to keep the master up
>> > while the future master is bootstrapping. Could
>> > a throttling in the number of transitions be enforced at partition
>> > level? Could I somehow specify that a state with a slave
>> > and a bootstrapping node is undesirable?
>> >
>> > As a note, I have also looked at the RSync-replicateed filesystem
>> > example. The reason for not using the OfflineOnline or the
>> > MasterSlave model in my application is that I would like the
>> > bootstrapping node to receive updates from clients, i.e. be visible
>> > during the bootstrap. For this reason, I am introducing the new
>> > BOOTSTRAPPING phase in-between OFFLINE and SLAVE.
>> >
>> > Regards,
>> > Vlad
>> >
>> >
>> > PS: The state model definition is as follows:
>> >
>> > builder.addState(MASTER, 1); а а а а а а а а а а а а а а а а
а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а
>> >
>> > а а а а а а builder.addState(SLAVE, 2);а а а а а а а а а а а
а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.addState(BOOTSTRAP, 3);а а а а а а а а а
а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.addState(OFFLINE); а а а а а а а а а а а
а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.addState(DROPPED); а а а а а а а а а а а
а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а // Set the initial state when the node startsа а а а а
а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.initialState(OFFLINE); а а а а а а а а а
а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > аа а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а // Add transitions between the states. а а а а а а а
а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.addTransition(OFFLINE, BOOTSTRAP, 4);а а а а а
а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.addTransition(BOOTSTRAP, SLAVE, 5);а а а а а
а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.addTransition(SLAVE, MASTER, 6); а а а а а а
а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.addTransition(MASTER, SLAVE, 3); а а а а а а
а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.addTransition(SLAVE, OFFLINE, 2);а а а а а а
а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.addTransition(OFFLINE, DROPPED, 1);а а а а а
а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > аа а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а // set constraints on states.а а а а а а а а а а
а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а // static constraint а а а а а а а а а а а а а
а а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.upperBound(MASTER, 1); а а а а а а а а а
а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а // dynamic constraint, R means it should be derived based
>> > on the replication а а а а а а а а а а а а а а а а а а а
а а а а а а а
>> > а а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а // factor. а а а а а а а а а а а а а а а а
а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а а а а а а а а а
а а а а а а а а а а
>> > а а а а а а а а а а а а а а а а а а
>> >
>> > а а а а а а builder.dynamicUpperBound(SLAVE, "R");а а а а а а а
а а а а
>> >
>> >
>> >
>> >
>>
>>
>
>

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