CODEWITHSUNDEEP
javadistributedhazelcast
tkroman
tkroman

Reputation: 4798

How do I run two Hazelcast nodes that share single data structure?

Say I have 2 nodes with IPs 192.168.5.101 and 192.168.5.102. I'd like to launch first one with some task initializing a distributed map and, in a couple of minutes, the second one (on those two hosts). How should I configure them to be able to see one another and to share that Map?

UPD. I had a glance at the Hazelcast docs and managed to run two instances with the following code:

Config config = new Config();
config.getNetworkConfig().getJoin().getMulticastConfig().setEnabled(false);
config.getNetworkConfig().getJoin().getTcpIpConfig().addMember("192.168.4.101").addMember("192.168.4.102").setRequiredMember("192.168.4.101").setEnabled(true);
config.getNetworkConfig().getInterfaces().setEnabled(true).addInterface("192.168.4.*");

And somewhere further:

HazelcastInstance hazelcast = Hazelcast.newHazelcastInstance(config);
MultiMap<Long, Long> idToPids = hazelcast.getMultiMap("mapName");
IMap<Long, EntityDesc> idToDesc = hazelcast.getMap("multiMapName");

All that followed by some job-performing code. I run this class on two different nodes, they successfully see each other and communicate (even share the resources, as far as I can tell).

But the problem is the work of two nodes seems a lot slower than in the case of single local node. What am I doing wrong?

Upvotes: 0

Views: 1133

Answers (1)

pveentjer
pveentjer

Reputation: 11307

One of the reasons of a slow down is that the data used in the tasks (I don't know anything about them) could be stored on a different member than the task is running. With a single node cluster, you don't have this problem. But with a multi node cluster, the map will be partitioned, so every member will only store a subset of the data.

Also with a single node, there is no backup and therefor it is a lot faster, than in a true clustered setup (so >1 members).

These are some of the obvious reasons why things could slow down. But without additional information, it will be very hard to guess what is the cause.

Upvotes: 0

Related Questions