The option -Dhazelcast.jmx=true seems to have no effect if I connect to the cluster as a cient:
hzInstance = HazelcastClient.newHazelcastClient(clientConfig);
It works in server mode. What am I doing wrong?
As per the documentation:
You can monitor your Hazelcast members via the JMX protocol
Emphasis mine. As such, you can only get the JMX metrics on a server JVM, from the Hazelcast node it's running.
Related
In datastax driver 3.x,we've DCAwareRoundRobin policy,which tries to connect to remote nodes if nodes in local datacenter fails.In the datastax drvier 4.x,we donot have that policy and confines to local-only.But,in the datastax docs,it's mentioned as:
Cross-datacenter failover is enabled with the following configuration option:
datastax-java-driver.advanced.load-balancing-policy.dc-failover {
max-nodes-per-remote-dc = 2
}
The driver will then attempt to open connections to nodes in remote datacenter.But,in the driver,we specify only a single datacenter to connect to as below:
CqlSession session = CqlSession.builder()
.addContactPoint(new InetSocketAddress("1.2.3.4", 9042))
.addContactPoint(new InetSocketAddress("5.6.7.8", 9042))
.withLocalDatacenter("datacenter1")
.build();
How the connection to remote datacenter is handled?Please help..
The quick answer is you don't do it programatically -- the Java driver does it for you after you've enabled advanced.load-balancing-policy.dc-failover.
The contact points are just the initial hosts the driver "contacts" to discover the cluster topology. After it has collected metadata about the cluster, it knows about nodes in remote DCs.
Since you've configured max-nodes-per-remote-dc = 2, the driver will add 2 nodes from each remote DC to the end of the query plan. The nodes in the local DC will be listed first then followed by the remote nodes. If the driver can't contact the nodes in the local DC, then it will start contacting the remote nodes in the query plan, one node at a time until it runs out of nodes to contact.
But I have to reiterate what I said in your other question, we do not recommend enabling DC-failover. For anyone else coming across this answer, you've been warned. Cheers!
I have 10 Cassandra Nodes running on Kubernetes on my server and 1 contact point that expose the service on port 10023.
However, when the datastax driver tries to establish a connection with the other nodes of the cluster it uses the exposed port instead of the default one and i get the following error:
com.datastax.driver.core.ConnectionException: [/10.210.1.53:10023] Pool was closed during initialization
Is there a way to expose one single contact point and have it to communicate with the other nodes on the standard port (9042)?
i checked on the datastax documentation if there is anything related to it but i didn't find much.
this is how i connect to the cluster
Cluster.Builder builder = Cluster.builder();
builder.addContactPoints(address)
.withPort(Integer.valueOf(10023))
.withCredentials(user, password)
.withMaxSchemaAgreementWaitSeconds(600)
.withSocketOptions(
new SocketOptions()
.setConnectTimeoutMillis(Integer.valueOf(timeout))
.setReadTimeoutMillis(Integer.valueOf(timeout))
).build();
Cluster cluster = builder.withoutJMXReporting().build();
Session session = cluster.connect();
After driver contacts first node, it fetches information about cluster, and use this information, and this information includes on what ports Cassandra listens.
To implement what you want to do, you need that Cassandra listened on the corresponding port - this is configured via native_transport_port parameter of the cassandra.yaml.
Also, by default Cassandra driver will try to connect to all nodes in cluster because it uses DCAware/TokenAware load balancing policy. If you want to use only one node, then you need to use WhiteListPolicy instead of default policy. But is not optimal from the performance point of view.
I would suggest to re-think how you expose Cassandra to clients.
We are using the latest Apache Cassandra database server, and the Datastax Node.js client, running in the cloud.
When our Cassandra servers are rebuilt, they get new IP addresses. Then any running service clients can't find the new servers, the client driver obviously must cache the IP addresses, instead of using DNS.
Is there some way around this problem, other than doing client shutdown and get a new client, in our services when we encounter an error accessing the database?
If you only have 1 server, there is nothing you can do.
Otherwise the node when it rebuilds (if it is a single node in the cluster of many) will advertise the new IP to the cluster and cluster topology is updated. So the peers table will be updated and the driver can register this event (AFAIK).
But why not use private static addresses for your cassandra nodes?
How to enable cassandra port to connect with BI application. Here my setup with cassandra is of multiple nodes (192.xxx.xx.01,192.xxx.xx.02,192.xxx.xx.03). In this scenario which node will be acting like master / coordinator with my application.
Although i worked with listen_address, rpc_address, broadcast_rpc_address and seeds, I opened both tcp ports 9042 and 9160.
version: 3.10
Kindly, lead me to the right direction.
Cassandra uses master-less architecture.All nodes are equal in cassandra.
When you connect to one of the node that node act as co-ordinator node, any of the node can be co-ordinator.
The coordinator is selected by the driver based on the policy you have set. Common policies are DCAwareRoundRobinPolicy and TokenAware Policy.
For DCAwareRoundRobinPolicy, the driver selects the coordinator node based on its round robin policy. See more here: http://docs.datastax.com/en/drivers/java/2.1/com/datastax/driver/core/policies/DCAwareRoundRobinPolicy.html
For TokenAwarePolicy, it selects a coordinator node that has the data being queried - to reduce "hops" and latency. More info: http://docs.datastax.com/en/drivers/java/2.1/com/datastax/driver/core/policies/TokenAwarePolicy.html
native_transport_port is 9042 by default and clients use native transport by default.
Hence you should have connection from your BI to Cassandra host on port 9042.
I am using Cassandra 1.2.8 with Thrift API currently i am working remotely with only my local server. But i need to connect it with a cluster on my production servers. I can easily connect with cluster using Hector API but i have done most of my development using Thrift so i don't want to shift to Hector.
with Thrift i am connecting to a server with this code
TTransport tr = new TFramedTransport(new TSocket("10.11.11.111", 9160));
TProtocol proto = new TBinaryProtocol(tr, true, true);
Cassandra.Client client = new Cassandra.Client(proto);
tr.open();
Please guide me how to do this
Thanks
When you connect with one machine from the cluster, you are automatically connected to the whole cluster. The cluster manages the distribution etc. of the data transparently to your application, you need just one server to talk to, and it can be any one. It's really that simple.