GeeksSpot

  Class ConnectionManager {   Queue<Connection> availableConnection;   List <Connection> allotedConnection; ConnectionManager( Integer noOfConnections, ConnectionPoperties props ) {     //Create the no of connection objects and assign to avaialbleConnection } Conection getConnection() {     syncronized( this.class) { if (availableConnection.isEmpty() ) {          throw ConnectionExhausted();       }       conn = availableCOnnection.poll();       alottledConectiion.add(conn); } return conn; } synchronized Conection releaseConnection(Connection conn) {        alottedconnection.remove(conn);    avaialbleConection.add(conn); }

  So we have 2 thread, one will be printing odd numbers and others will be printing even number. We have to print them in a synchronized fashion.  class Lock {     Boolean isOdd;     Lock(Boolean odd) {         this.isOdd = odd;     }     synchronized void print(Integer number) {         Boolean numberEven = number %2 == 0;         while (isOdd == numberEven) {             try {                 wait();             } catch( InterruptedException e) {                Thread.currentThread().interrupt();             }         }         System.out.println(number);         isOdd = !isOdd;         notify();     } } class PrintThread extends Thread{   Integer limit;    Integer value;   Lock lock;   PrintThread( Integer start,Integer limit, Lock lock) {      this.value = start;      this.limit = limit; this.lock = lock;   }       public void run() {    while( value < limit ) {            lock.print(value);    value +=2;         }   } } public class Test {  static public void main(String

 We all wish that our application used by maximum people on Earth. To make sure we have the right scalable application, please follow below guidelines  1. Load balancing at all level of application i.e. web server, application server and DB server 2. Remote caching to be enabled for a fast response.  3. Load balancer will equally distribute the traffic to existing servers, what if enough capacity is not enough. We should have a mechanism to increase the server capacity (esp horizontally ).  All the cloud service provider has provision for autoscaling, so do Kubernetes.  Use them.  4. Most of the NoSQL DB comes with good support for horizontal scalability. So if you chosse NoSQL you can easily scale them. But if your application requires RDBMS (SQL) then plan should be with sharding in place.  5. Server should be stateless. Any server should be able to serve an incoming request. No local storage, no IP binding. Having said newly added server will start serving instantly.  6. CI and CD s