Develop Reference

Amazon Keyspace (Cassandra) query no node was available to execute query

I'm using AWS Keyspace (Cassandra 3.11.2) run on Apache Flink in AWS EMR. Some time below query throws Exception. The same code used on AWS Lambda also had the same Exception NoHost. What did I do wrong?
String query = "INSERT INTO TEST (field1, field2) VALUES(?, ?)";
PreparedStatement prepared = CassandraConnector.prepare(query);
int i = 0;
BoundStatement bound = prepared.bind().setString(i++, "Field1").setString(i++, "Field2")
.setConsistencyLevel(ConsistencyLevel.LOCAL_QUORUM);
ResultSet rs = CassandraConnector.execute(bound);
at com.datastax.oss.driver.api.core.NoNodeAvailableException.copy(NoNodeAvailableException.java:40)
at com.datastax.oss.driver.internal.core.util.concurrent.CompletableFutures.getUninterruptibly(CompletableFutures.java:149)
at com.datastax.oss.driver.internal.core.cql.CqlRequestSyncProcessor.process(CqlRequestSyncProcessor.java:53)
at com.datastax.oss.driver.internal.core.cql.CqlRequestSyncProcessor.process(CqlRequestSyncProcessor.java:30)
at com.datastax.oss.driver.internal.core.session.DefaultSession.execute(DefaultSession.java:230)
at com.datastax.oss.driver.api.core.cql.SyncCqlSession.execute(SyncCqlSession.java:53)
at com.test.manager.connectors.CassandraConnector.execute(CassandraConnector.java:16)
at com.test.repository.impl.BackupRepositoryImpl.insert(BackupRepositoryImpl.java:36)
at com.test.service.impl.BackupServiceImpl.insert(BackupServiceImpl.java:18)
at com.test.flink.function.AsyncBackupFunction.processMessage(AsyncBackupFunction.java:78)
at com.test.flink.function.AsyncBackupFunction.lambda$asyncInvoke$0(AsyncBackupFunction.java:35)
at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1604)
at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1596)
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
This is my code:
CassandraConnector.java:
Because cost of init preparedStatement is huge, I'm cached this.
public class CassandraConnector {
private static final ConcurrentHashMap<String, PreparedStatement> preparedStatementCache = new ConcurrentHashMap<String, PreparedStatement>();
public static ResultSet execute(BoundStatement bound) {
CqlSession session = CassandraManager.getSessionInstance();
return session.execute(bound);
}
public static ResultSet execute(String query) {
CqlSession session = CassandraManager.getSessionInstance();
return session.execute(query);
}
public static PreparedStatement prepare(String query) {
PreparedStatement result = preparedStatementCache.get(query);
if (result == null) {
CqlSession session = CassandraManager.getSessionInstance();
result = session.prepare(query);
preparedStatementCache.putIfAbsent(query, result);
}
return result;
}
}
CassandraManager.java:
I'm using singleton double-check locking for session object.
public class CassandraManager {
private static final Logger logger = LoggerFactory.getLogger(CassandraManager.class);
private static final String SSL_CASSANDRA_PASSWORD = "password";
private static volatile CqlSession session;
static {
try {
initSession();
} catch (Exception e) {
logger.error("Error CassandraManager getSessionInstance", e);
}
}
private static void initSession() {
List<InetSocketAddress> contactPoints = Collections.singletonList(InetSocketAddress.createUnresolved(
"cassandra.ap-southeast-1.amazonaws.com", 9142));
DriverConfigLoader loader = DriverConfigLoader.fromClasspath("application.conf");
Long start = BaseHelper.getTime();
session = CqlSession.builder().addContactPoints(contactPoints).withConfigLoader(loader)
.withAuthCredentials(AppUtil.getProperty("cassandra.username"),
AppUtil.getProperty("cassandra.password"))
.withSslContext(getSSLContext()).withLocalDatacenter("ap-southeast-1")
.withKeyspace(AppUtil.getProperty("cassandra.keyspace")).build();
logger.info("End connect: " + (new Date().getTime() - start));
}
public static CqlSession getSessionInstance() {
if (session == null || session.isClosed()) {
synchronized (CassandraManager.class) {
if (session == null || session.isClosed()) {
initSession();
}
}
}
return session;
}
public static SSLContext getSSLContext() {
InputStream in = null;
try {
KeyStore ks = KeyStore.getInstance("JKS");
in = CassandraManager.class.getClassLoader().getResourceAsStream("cassandra_truststore.jks");
ks.load(in, SSL_CASSANDRA_PASSWORD.toCharArray());
TrustManagerFactory tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
tmf.init(ks);
SSLContext ctx = SSLContext.getInstance("TLS");
ctx.init(null, tmf.getTrustManagers(), null);
return ctx;
} catch (Exception e) {
logger.error("Error CassandraConnector getSSLContext", e);
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
logger.error("", e);
}
}
}
return null;
}
}
application.conf
datastax-java-driver {
basic.request {
timeout = 5 seconds
consistency = LOCAL_ONE
}
advanced.connection {
max-requests-per-connection = 1024
pool {
local.size = 1
remote.size = 1
}
}
advanced.reconnect-on-init = true
advanced.reconnection-policy {
class = ExponentialReconnectionPolicy
base-delay = 1 second
max-delay = 60 seconds
}
advanced.retry-policy {
class = DefaultRetryPolicy
}
advanced.protocol {
version = V4
}
advanced.heartbeat {
interval = 30 seconds
timeout = 1 second
}
advanced.session-leak.threshold = 8
advanced.metadata.token-map.enabled = false
}

There are two scenarios where the driver would report NoNodeAvailableException:
Nodes are unresponsive/unavailable and the driver has marked all of them as down.
All the contact points provided are invalid.
If some inserts are working but eventually runs into NoNodeAvailableException, that indicates to me that the nodes are getting overloaded and eventually become unresponsive so the driver no longer picks a coordinator since they're all marked as "down".
If none of the requests work at all, it means that the contact points are unreachable or unresolvable so the driver can't connect to the cluster. Cheers!

The NoHostAvailableException is a client side exception thrown by the open source driver after it has retried available hosts. The open source driver encapsulated the root cause for retry, which can be confusing.
I suggest first improving you observability by setting up these CloudWatch metrics. You can follow this prebuild CloudFormation template to get started it only takes a few seconds.
Here is a set up for Keyspace & Table Metrics for Amazon Keyspaces using Cloud Watch:
https://github.com/aws-samples/amazon-keyspaces-cloudwatch-cloudformation-templates
You can also replace retry policy with the following examples found in this helper project. The retry policy in this project will either try or throw the original exception which will remove the occurrences of NoHostAvailableException this will provide you with better transparency to your application. Here's the like to the Github repo: https://github.com/aws-samples/amazon-keyspaces-java-driver-helpers
If you're using the private VPC endpoint you want to add the following permissions to enable more entries in the system.peers table.,
Amazon Keyspaces just announced new functionality that will provide more connection points when establishing a session with a private VPC endpoints.
Here is a link about how Keyspaces now automatically optimizes client connection made through AWS PrivateLink to improve availability and write and read: https://aws.amazon.com/about-aws/whats-new/2021/07/amazon-keyspaces-for-apache-cassandra-now-automatically-optimi/
This link that talks about Using Amazon Keypscaes with Interface VPC Endpoints: https://docs.aws.amazon.com/keyspaces/latest/devguide/vpc-endpoints.html . To enable this new functionality you will need to provide additional permissions to DescribeNetworkInterfaces and DescribeVpcEndpoints.
{
"Version":"2012-10-17",
"Statement":[
{
"Sid":"ListVPCEndpoints",
"Effect":"Allow",
"Action":[
"ec2:DescribeNetworkInterfaces",
"ec2:DescribeVpcEndpoints"
],
"Resource":"*"
}
]
}

I suspect that this:
.withLocalDatacenter(AppUtil.getProperty("cassandra.localdatacenter"))
Pulls back a data center name which either does not match the keyspace replication definition or the configured data center name:
nodetool status | grep Datacenter
Basically, if your connection is defined with a local data center which does not exist, it will still try to read/write with replicas in that data center. This will fail, because it obviously cannot find nodes in a non-existent data center.
Similar question here: NoHostAvailable error in cqlsh console

SSL Handshake is not happening from the pipeline while doing reconnection to servers

Problem I'm facing is the something like this :
in Main class, I'll try to connect to a server and attach Channel Listener for future actions.
If Connection establishes successfully, SSL Handshake is done without any problem.
But if Connection in Step 1 fails, I'll try to connect to same or different server and again attach same channel listener same as point.
But expectation is it should SSL handshake as before in point 2 if connection is established. But it's not. Even if I forcefully call renegotiate metthod in SslHandler.
Expected behavior
If any connection exception using bootstrap object to connect to the server, expectation is it should SSL handshake.
Actual behavior
It's skipping the SSL handshake while retrying and failing with UnknownMessage type expected(ByteBuf)
Steps to reproduce
While Main Connection
public class Main {
private final static Logger LOGGER = LoggerFactory.getLogger(Main.class);
public static void main(String[] args) {
ClientConfig clientConfig = null;
LOGGER.info("initializing Agent Stats uploader");
// Set up.
InternalLoggerFactory.setDefaultFactory(Slf4JLoggerFactory.INSTANCE);
Bootstrap clientBootstrap = getBootstrap();
clientConfig = ClientConfig.getInstance();
InetSocketAddress server = clientConfig.getPrimaryScnInetAddrs();
Objects.nonNull(server.getHostName());
Objects.nonNull(server.getPort());
// Make a new connection.
LOGGER.info("Initialization complete, ready to connect to the host and port {}:{}", server.getHostName(),
server.getPort());
ServerChannelFutureListener serverChannelFutureListener = ServerChannelFutureListener.getInstance();
serverChannelFutureListener.setClientBootStrap(clientBootstrap);
ChannelPromise channelPromise =
(ChannelPromise) clientBootstrap.connect(server).addListener(serverChannelFutureListener);
EventLoopGroup eventGroupExecutor = clientBootstrap.config().group();
AgentStatsProcess agentStatsThread = AgentStatsProcess.getInstance();
agentStatsThread.setParentChannelFuture(channelPromise);
eventGroupExecutor.scheduleAtFixedRate(agentStatsThread, clientConfig.getInitialDelay(),
clientConfig.getScheduleInterval(), TimeUnit.SECONDS);
LOGGER.info("Scheduled Agent Stats uploading, should start in 30 secs");
LOGGER.info("Connection complete");
Runtime.getRuntime().addShutdownHook(new Thread(() -> {
LOGGER.info("Killing AgentStatUploader Thread");
eventGroupExecutor.shutdownGracefully();
}));
}
public static final Bootstrap getBootstrap() {
EventLoopGroup group = new NioEventLoopGroup();
Bootstrap b = new Bootstrap();
b.group(group);
b.channel(NioSocketChannel.class);
b.handler(new AgentStatsChannelInitializationHandler());
b.option(ChannelOption.SO_KEEPALIVE, true);
b.option(ChannelOption.TCP_NODELAY, true);
return b;
}
}
Having Channel Future handler for implementing re-try logic in step 1
public final class ServerChannelFutureListener implements GenericFutureListener {
private static final Logger logger = LoggerFactory.getLogger(ServerChannelFutureListener.class.getName());
private static ServerChannelFutureListener instance;
private AtomicInteger count = new AtomicInteger(1);
private ClientConfig clientConfig = ClientConfig.getInstance();
private boolean isPrimary=true;
private ChannelFuture channelFuture;
private Bootstrap clientBootStrap;
private long timeout;
private ServerChannelFutureListener(){
this.timeout = clientConfig.getRetryAfter();
}
#override
public void operationComplete(ChannelFuture future) throws Exception {
channelFuture = future;
int maxretries = clientConfig.getMaxRetries();
if (!future.isSuccess()) {
logger.info("Connection to {} scn is not successful, retrying ({}/{})", getServerType(), count.get(),maxretries);
logger.debug("Connection to server is failed with error: ",future.cause());
if ( count.incrementAndGet() > maxretries) {
// fails to connect even after max-retries, try to connect to next server.
logger.info("Failed to connect to {} server, will try to connect to {} now.",
getServerType(),
isPrimary() ? "SECONDARY":"PRIMARY");
count.getAndSet(1);
isPrimary = !isPrimary();
this.timeout = clientConfig.getRetryAfter();
logger.info("Connecting Server type changed, so resetting timeout: {}", this.timeout);
}else{
// retry
logger.info("Exponential Back-off set to: {} secs, waiting for next server connection", this.timeout);
//TimeUnit.SECONDS.sleep(this.timeout);
this.timeout = ExpontentialBackOff.getNextBackOff(this.timeout);
}
InetSocketAddress server = getServer();
logger.info("Initialization complete, ready to connect to the host and port {}:{}", server.getHostName(),
server.getPort());
channelFuture = clientBootStrap.connect(server).addListener(this);
}else {
logger.info("Using Connection with config: {}, to Server {} ", future.channel().config(),
future.channel().localAddress());
this.timeout = clientConfig.getRetryAfter();
logger.info("Time out Back-off reset to: {} for next server connection", this.timeout);
}
AgentStatsProcess.getInstance().setParentChannelFuture(channelFuture);
}
private String getServerType() {
return isPrimary() ? "PRIMARY" : "SECONDARY";
}
private InetSocketAddress getServer(){
return isPrimary()?clientConfig.getPrimaryScnInetAddrs():clientConfig.getSecondaryScnInetAddrs();
}
public static ServerChannelFutureListener getInstance(){
if(null == instance){
instance = new ServerChannelFutureListener();
}
return instance;
}
public boolean isPrimary() {
return isPrimary;
}
public ChannelFuture getChannelFuture() {
return channelFuture;
}
public void setClientBootStrap(Bootstrap cb) {
this.clientBootStrap = cb;
}
}
Expectation is SSL Handshake should happen after trying to reconnect but its failing.
Netty version: 4.1.12.Final

Fixed this issue, Culprit here is "ProtobufVarint32FrameDecoder " and it's parent Class "ByteToMessageDecoder". "ByteToMessageDecoder" make sure it's child classes are not shareable.
Because above classes are not shareable, every time code try to reconnect using boostrap, initializer class fails to add handlers in pipeline results in "ctx.close()" and no handlers.
I've did work-around of adding those two classes into my project and raised #10371 bug to address this issue.

Apache Kafka Producer twitter connection IllegalStateException

I am trying to establish a connection with twitter client and getting the following exception:
This exception appears while establishing the base connection whereas zookeepers and Kafka server are running.
Exception in thread "main" java.lang.IllegalStateException: There is already a connection thread running for Hosebird-Client-01, endpoint: /1.1/statuses/filter.json?delimited=length&stall_warnings=true
at com.twitter.hbc.httpclient.BasicClient.connect(BasicClient.java:92)
at com.github.simpleProject.kafka.simpleProject.twitter.TwitterProducer.run(TwitterProducer.java:37)
at com.github.simpleProject.kafka.simpleProject.twitter.TwitterProducer.main(TwitterProducer.java:28)
Here is my code
public class TwitterProducer {
Logger logger = LoggerFactory.getLogger(TwitterProducer.class.getName());
String consumerKey ="sbkOd*********tMJQUpU4Iz4j";
String consumerSecret="eZZPa788***********TR6hx39MlkvWylO6rF";
String token = "758284333996277763-*************D6f5CanCsre2qPgviv";
String secret="jJRbC9cMOaacHEHEd7y6po********1VwsS5x0ZmDG";
public TwitterProducer(){}
public static void main(String[] args){
new TwitterProducer().run();
}
public void run(){
/** Set up your blocking queues: Be sure to size these properly based on expected TPS of your stream */
BlockingQueue<String> msgQueue = new LinkedBlockingQueue<String>(1000);
// create a twitter client
Client client = createTwitterClient(msgQueue);
// Attempts to establish a connection.
client.connect();
// create a kafka producer
// loops to send tweets to kafka
// on a different thread, or multiple different threads....
while (!client.isDone()) {
String msg =null;
try{
msg = msgQueue.poll(5, TimeUnit.SECONDS);
} catch (InterruptedException e){
e.printStackTrace();
client.stop();
}
if(msg!=null){
logger.info(msg);
}
logger.info("End of application");
}
}
public Client createTwitterClient(BlockingQueue<String> msgQueue){
/** Declare the host you want to connect to, the endpoint, and authentication (basic auth or oauth) */
Hosts hosebirdHosts = new HttpHosts(Constants.STREAM_HOST);
StatusesFilterEndpoint hosebirdEndpoint = new StatusesFilterEndpoint();
List<String> terms = Lists.newArrayList("bitcoin");
hosebirdEndpoint.trackTerms(terms);
// These secrets should be read from a config file
Authentication hosebirdAuth = new OAuth1(consumerKey, consumerSecret, token, secret);
ClientBuilder builder = new ClientBuilder()
.name("Hosebird-Client-01") // optional: mainly for the log
.hosts(hosebirdHosts)
.authentication(hosebirdAuth)
.endpoint(hosebirdEndpoint)
.processor(new StringDelimitedProcessor(msgQueue));
Client hosebirdClient = builder.build();
// Attempts to establish a connection.
hosebirdClient.connect();
return hosebirdClient;
}
}

connect to local cassandra nodes using datastax java driver?

I am using datastax java driver 3.1.0 to connect to cassandra cluster and my cassandra cluster version is 2.0.10.
Below is the singleton class I am using to connect to cassandra cluster.
public class CassUtil {
private static final Logger LOGGER = Logger.getInstance(CassUtil.class);
private Session session;
private Cluster cluster;
private static class Holder {
private static final CassUtil INSTANCE = new CassUtil();
}
public static CassUtil getInstance() {
return Holder.INSTANCE;
}
private CassUtil() {
List<String> servers = TestUtils.HOSTNAMES;
String username =
TestUtils.loadCredentialFile().getProperty(TestUtils.USERNAME);
String password =
TestUtils.loadCredentialFile().getProperty(TestUtils.PASSWORD);
// is this right setting?
PoolingOptions poolingOptions = new PoolingOptions();
poolingOptions.setConnectionsPerHost(HostDistance.LOCAL, 4, 10).setConnectionsPerHost(
HostDistance.REMOTE, 2, 4);
Builder builder = Cluster.builder();
cluster =
builder
.addContactPoints(servers.toArray(new String[servers.size()]))
.withRetryPolicy(DowngradingConsistencyRetryPolicy.INSTANCE)
.withPoolingOptions(poolingOptions)
.withReconnectionPolicy(new ConstantReconnectionPolicy(100L))
.withLoadBalancingPolicy(
DCAwareRoundRobinPolicy
.builder()
.withLocalDc(
!TestUtils.isProduction() ? "DC2" : TestUtils.getCurrentLocation()
.get().name().toLowerCase()).build())
.withCredentials(username, password).build();
try {
session = cluster.connect("testkeyspace");
StringBuilder sb = new StringBuilder();
Set<Host> allHosts = cluster.getMetadata().getAllHosts();
for (Host host : allHosts) {
sb.append("[");
sb.append(host.getDatacenter());
sb.append(host.getRack());
sb.append(host.getAddress());
sb.append("]");
}
LOGGER.logInfo("connected: " + sb.toString());
} catch (NoHostAvailableException ex) {
LOGGER.logError("error= ", ExceptionUtils.getStackTrace(ex));
} catch (Exception ex) {
LOGGER.logError("error= " + ExceptionUtils.getStackTrace(ex));
}
}
public void shutdown() {
LOGGER.logInfo("Shutting down the whole cassandra cluster");
if (null != session) {
session.close();
}
if (null != cluster) {
cluster.close();
}
}
public Session getSession() {
if (session == null) {
throw new IllegalStateException("No connection initialized");
}
return session;
}
public Cluster getCluster() {
return cluster;
}
}
What is the settings I need to use to connect to local cassandra nodes first and if they are down, then only talk to remote nodes. Also my pooling configuration options is right here which I am using in the above code?

By default the datastax drivers will only connect to nodes in the local DC. If you do not use withLocalDc it will attempt to discern the local datacenter from the DC of the contact point it is able to connect to.
If you want the driver to fail over to host in remote data center(s) you should use withUsedHostsPerRemoteDc, i.e.:
cluster.builder()
.withLoadBalancingPolicy(DCAwareRoundRobinPolicy.builder()
.withLocalDc("DC1")
.withUsedHostsPerRemoteDc(3).build())
With this configuration, the driver will establish connections to 3 hosts in each remote DC, and only send queries to them if all hosts in the local datacenter is down.
There are other strategies for failover to remote data centers. For example, you could run your application clients in each same physical data center as your C* data centers, and then when a physical data center fails, you can fail over at a higher level (like your load balancer).
Also my pooling configuration options is right here which I am using in the above code?
I think what you have is fine. The defaults are fine too.

cassandra single node connection error

i am trying to use cassandra as database for an app i am working on. The app is a Netbeans platform app.
In order to start the cassandra server on my localhost i issue Runtime.getRuntime().exec(command)
where command is the string to start the cassandra server and then i connect to the cassandra sever with the datastax driver. However i get the error:
com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /127.0.0.1:9042 (com.datastax.driver.core.TransportException: [/127.0.0.1:9042] Cannot connect))
at com.datastax.driver.core.ControlConnection.reconnectInternal(ControlConnection.java:199)
at com.datastax.driver.core.ControlConnection.connect(ControlConnection.java:80)
at com.datastax.driver.core.Cluster$Manager.init(Cluster.java:1154)
at com.datastax.driver.core.Cluster.getMetadata(Cluster.java:318)
at org.dhviz.boot.DatabaseClient.connect(DatabaseClient.java:43)
at org.dhviz.boot.Installer.restored(Installer.java:67)
....
i figure it out that the server requires some time to start so i have added the line Thread.sleep(MAX_DELAY_SERVER) which seem to resolve the problem.
Is there any more elegant way to sort this issue?
Thanks.
Code is below.
public class Installer extends ModuleInstall {
private final int MAX_DELAY_SERVER = 12000;
//private static final String pathSrc = "/org/dhviz/resources";
#Override
public void restored() {
/*
-*-*-*-*-*DESCRIPTION*-*-*-*-*-*
IMPLEMENT THE CASSANDRA DATABASE
*********************************
*/
DatabaseClient d = new DatabaseClient();
// launch an instance of the cassandra server
d.loadDatabaseServer();
/*wait for MAX_DELAY_SERVER milliseconds before launching the other instructions.
*/
try {
Thread.sleep(MAX_DELAY_SERVER);
Logger.getLogger(Installer.class.getName()).log(Level.INFO, "wait for MAX_DELAY_SERVER milliseconds before the connect database");
} catch (InterruptedException ex) {
Exceptions.printStackTrace(ex);
Logger.getLogger(Installer.class.getName()).log(Level.INFO, "exeption in thread sleep");
}
d.connect("127.0.0.1");
}
}
public class DatabaseClient {
private Cluster cluster;
private Session session;
private ShellCommand shellCommand;
private final String defaultKeyspace = "dhviz";
final private String LOAD_CASSANDRA = "launchctl load /usr/local/Cellar/cassandra/2.1.2/homebrew.mxcl.cassandra.plist";
final private String UNLOAD_CASSANDRA = "launchctl unload /usr/local/Cellar/cassandra/2.1.2/homebrew.mxcl.cassandra.plist";
public DatabaseClient() {
shellCommand = new ShellCommand();
}
public void connect(String node) {
//this connect to the cassandra database
cluster = Cluster.builder()
.addContactPoint(node).build();
// cluster.getConfiguration().getSocketOptions().setConnectTimeoutMillis(12000);
Metadata metadata = cluster.getMetadata();
System.out.printf("Connected to cluster: %s\n",
metadata.getClusterName());
for (Host host
: metadata.getAllHosts()) {
System.out.printf("Datatacenter: %s; Host: %s; Rack: %s\n",
host.getDatacenter(), host.getAddress(), host.getRack());
}
session = cluster.connect();
Logger.getLogger(DatabaseClient.class.getName()).log(Level.INFO, "connected to server");
}
public void loadDatabaseServer() {
if (shellCommand == null) {
shellCommand = new ShellCommand();
}
shellCommand.executeCommand(LOAD_CASSANDRA);
Logger.getLogger(DatabaseClient.class.getName()).log(Level.INFO, "database cassandra loaded");
}
public void unloadDatabaseServer() {
if (shellCommand == null) {
shellCommand = new ShellCommand();
}
shellCommand.executeCommand(UNLOAD_CASSANDRA);
Logger.getLogger(DatabaseClient.class.getName()).log(Level.INFO, "database cassandra unloaded");
}
}

If you are calling cassandra without any parameters in Runtime.getRuntime().exec(command) it's likely that this is spawning cassandra as a background process and returning before the cassandra node has fully started and is listening.
I'm not sure why you are attempting to embed cassandra in your app, but you may find using cassandra-unit useful for providing a mechanism to embed cassandra in your app. It's primarily used for running tests that require a cassandra instance, but it may also meet your use case.
The wiki provides a helpful example on how to start an embedded cassandra instance using cassandra-unit:
EmbeddedCassandraServerHelper.startEmbeddedCassandra();
In my experience cassandra-unit will wait until the server is up and listening before returning. You could also write a method that waits until a socket is in use, using logic opposite of this answer.

I have changed the code to the following taking inspiration from the answers below. Thanks for your help!
cluster = Cluster.builder()
.addContactPoint(node).build();
cluster.getConfiguration().getSocketOptions().setConnectTimeoutMillis(50000);
boolean serverConnected = false;
while (serverConnected == false) {
try {
try {
Thread.sleep(MAX_DELAY_SERVER);
} catch (InterruptedException ex) {
Exceptions.printStackTrace(ex);
}
cluster = Cluster.builder()
.addContactPoint(node).build();
cluster.getConfiguration().getSocketOptions().setConnectTimeoutMillis(50000);
session = cluster.connect();
serverConnected = true;
} catch (NoHostAvailableException ex) {
Logger.getLogger(DatabaseClient.class.getName()).log(Level.INFO, "trying connection to cassandra server...");
serverConnected = false;
}
}