Removed ability to disable connection pool (#337)

pulsar-client/src/main/java/com/yahoo/pulsar/client/api/ClientConfiguration.java

@@ -211,12 +211,13 @@ public class ClientConfiguration implements Serializable {
      * By default, the connection pool will use a single connection for all the producers and consumers. Increasing this
      * parameter may improve throughput when using many producers over a high latency connection.
      * <p>
-     * Setting connections per broker to 0 will disable the connection pooling.
      *
      * @param connectionsPerBroker
-     *            max number of connections
+     *            max number of connections per broker (needs to be greater than 0)
      */
     public void setConnectionsPerBroker(int connectionsPerBroker) {
+        checkArgument(connectionsPerBroker > 0,
+                "Connections per broker need to be greater than 0");
         this.connectionsPerBroker = connectionsPerBroker;
     }
 

pulsar-testclient/src/main/java/com/yahoo/pulsar/testclient/PerformanceConsumer.java

@@ -84,7 +84,7 @@ public class PerformanceConsumer {
 
         @Parameter(names = { "-c",
                 "--max-connections" }, description = "Max number of TCP connections to a single broker")
-        public int maxConnections = 0;
+        public int maxConnections = 100;
 
         @Parameter(names = { "-i",
                 "--stats-interval-seconds" }, description = "Statistics Interval Seconds. If 0, statistics will be disabled")

pulsar-testclient/src/main/java/com/yahoo/pulsar/testclient/PerformanceProducer.java

@@ -111,7 +111,7 @@ public class PerformanceProducer {
 
         @Parameter(names = { "-c",
                 "--max-connections" }, description = "Max number of TCP connections to a single broker")
-        public int maxConnections = 0;
+        public int maxConnections = 100;
 
         @Parameter(names = { "-m",
                 "--num-messages" }, description = "Number of messages to publish in total. If 0, it will keep publishing")