From the docs, there is a class called Cluster, but other than for the LocalCluster, I can not find any docs about how to setup a Cluster which accepts workers from different machines (as this is described for LocalClusterhere.
Are there some recommendations out there?
Related question: 1 (only reference on the docs as above)
The answer is SSHCluster
It is based on asyncsshand can have multiple workers per machine in the cluster. Make sure to have pre requirements installed.
Related
I am implementing geode dunit based tests.Each VM executes Callable asynchronously.The logic is having several steps , between which the VMs need to be synced up. Its not possible to separate them into several different callable s because some variables need to be persisted between stages.
Currently the VMs are doing sleep after each stage and this way the VMs are synced. However i am looking for another option which would allow execution without sleep ( semaphore based ).
Is there an option to have a shared resource between VMs that would allow to sync up the VMs , or may be some geode based mechanism that would allow such orchestration of VMs?
BR
Yulian Oifa
Geode's internal testing framework does this in several places, actually, I'd suggest having a look at the geode-dunit project for examples, specially at the Blackboard java class.
Cheers.
So I would like to ask if there will be any contention issues due to shared access to the same Redis cluster by multiple separate applications which use Redisson library (each application in turn has several instances of themselves).
Does Redisson library support such use case? Or do I need to configure Redisson in each application, for example add some kind of prefix or app name (as it is possible with Quartz where you can define prefixes for tables used by separate applications having access to the same db and using Quartz independently).
Won't the tasks submitted to ExecutorService in one app be forwarded to completely another application which also uses Redisson and not to another instance of the same application?
I would recommend you to use prefix/suffix in Redisson's object names when you share same Redis setup in cluster mode across multiple independent applications.
Please be aware that I am a relative newbie to ActiveMQ.
I am currently working with a small cluster of ActiveMQ (version 5.15.x) nodes (< 5). I recently experimented with setting up the configuration to use "Shared File System Master Slave" with kahadb, in order to provide high availability to the cluster.
Having done so and seeing how it operates, I'm now considering whether this configuration provides the level of throughput required for both consumers/producers, as only one broker's ports are available at one time.
My question is basically two part. First, does it make sense to configure the cluster as highly available AND load balanced (through Network of Brokers)? Second, is the above even technically viable, or do I need to review my design consideration to favor one aspect over the other?
I had some discussions with the ActiveMQ maintainers in IRC on this topic a few months back.
It seems that they would recommend using ActiveMQ Artemis instead of ActiveMQ 5.
Artemis has a HA solution:
https://activemq.apache.org/artemis/docs/latest/clusters.html
https://activemq.apache.org/artemis/docs/latest/ha.html
The idea is to use Data Replication to allow for failover, etc:
When using replication, the live and the backup servers do not share the same data directories, all data synchronization is done over the network. Therefore all (persistent) data received by the live server will be duplicated to the backup.
And, I think you want to have at least 3 nodes (or some odd number) to avoid issues with split brain during network partitions.
It seems like Artemis can mostly be used as a drop-in replacement for ActiveMQ; it can still speak the OpenWire protocol, etc.
However, I haven't actually tried this yet, so YMMV.
I am doing data base scaling using postgresql.
Currently i am using pg_shard for scaling and able to do sharding and replication. i have tested the example that mentioned in Readme file of pg_shard.
But i need dynamically scale a cluster as new machines are added or old ones are retired.I am using google cloud VM to setup database .So once one VM is filled with data i want to setup new instance with same configuration.
ie,if the current machine size is 4GB and is of out of memory then it should create one more VM with 4GB size and next entries should come there.
I have gone through http://slideplayer.com/slide/4896815/ and after reading this i understood that it is possible to do but the steps are not mentioned anywhere.
How to achieve this using pg_shard?
I got the answer myself.
We can use CitusDB for this.
CitusDB is installed with an extension called "shard_rebalancer", which helps you to move the shards around when new nodes are added to the cluster. For this, you need to follow the installation instructions for CitusDB.
In this documentation, you can find about the related information for the shard rebalancer functions (i.e., rebalance_table_shards and replicate_table_shards)
With simpler words, you must follow the steps:
Add CitusDB node(s) to the cluster
Add the IPs (or host names) to pg_worker_list.conf
Reload the master node configuration, so that the master becomes aware of the new worker node(s)
Run "SELECT rebalance_table_shards('tablename')" on the master node.
I have a service based architecture where a web farm full of asp clients hit application server farm of WCF services. Obviously all the database access is done by the WCF services. Now I would like to cache my frequently used database retrieved objects using Velocity at the service tier level. I am considering to make each physical application server also part of the cache cluster.
According to Velocity documentation, if I use regions, objects are stored only at a single host. I actually wouldn't have any problem if each host kept it's own cache provided that I could somehow synchronize them.
So my questions are
If I create one region on one host is it also created on another one?
When I clear a cache region, is it cleared on one host only?
If I subscribe to a region level notification on all the hosts, can I catch events of one host on another one?
In this scenario should I use regions at all or stay away from them?
I hope my questions are clear. Actually I am more interested in a solution to my problem than answers to my questions
Yes you are right in reading the doc that the region will exists only in one host.
" I actually wouldn't have any problem if each host kept it's own cache provided that I could somehow synchronize them."
When you say synchronize, you mean when HA in enabled ? Velocity would actually take care of that if thats what you meant.
For the questions:
1. No.
2. Yes
3. Notifications will be sent to the client. So i am not sure if there is anyway to send notifications to other host.
4. Regions gives Search capabilities and takes away HA from you. In your case, you could use the advantages of HA.
Having regions not necessarily means that you don't have HA. if your create your own cache (and don't use the 'default' one) you can create it with Secondarys = 1 (HA on)
now let’s say you have 4 cache hosts; when you define a region , it will have both primary and secondary hosts. so each action on the region will result it being applied in both.
Shany
Named caches distribute across participating nodes. Named regions live on a single node. Regions can be HA, but they cannot take full advantage of distributed cache scaling, as their object load does not distribute across participating nodes in the cluster. Also, using named caches with HA requires three nodes minimum, rather than two nodes if you used the "default" cache only.