Rabbitmq Priority Queue Write Performance Reduced as number of priorities increases - rabbitmq

Question

I am using Rabbitmq 3.7.3 with Java client 5.1.2 [amqp-client-5.1.2.jar] for priority queue. In my usecase I will be having maximum of 60 priorities in a single non persistence queue where only few upto 10-15 will be mostly used.
Case 1. If I have defined a queue to have 10 priorities, and messages ranging from 0 to 9 priorities are pushed to the queue, I am getting 12500 writes per second.
Case 2. If I have defined a queue to have 60 priorities, and messages ranging from 0-9 priorities are pushed to the queue, I am getting 4200 writes per second.
Case 3: If I have defined a queue to have 250 priorities, and messages ranging from 0-9 priorities are pushed to the queue, I am getting only 1500 writes per second.
What observed here is, as and when we increase the priorities capacity of a queue, though only very few being used, the write performance degrades.
Below is the code snippet: [Writes are done using single thread]
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.AMQP.BasicProperties;
import java.io.*;
import java.util.*;
public class Write implements Runnable{
int start;
int count;
int end;
private long unixTime;
private long timeTaken;
private long totalTimeTaken;
private long totalRequests;
private long minLatency;
private long maxLatency;
private double avgLatency;
private FileOutputStream out;
int parity = 1;
int ndnc = 0;
int mnp = 1001;
int blist = 0;
String value;
ConnectionFactory factory;
Connection connection;
Channel channel;
String QUEUE_NAME;
public Write(int s, int c){
this.start = s;
this.count = c;
this.end = this.count;
this.totalTimeTaken = 0;
this.totalRequests = 0;
this.minLatency = 1000000;
this.maxLatency = 0;
try{
this.QUEUE_NAME = "queuedata_4";
this.factory = new ConnectionFactory();
factory.setHost("192.168.1.100");
factory.setUsername("user");
factory.setPassword("pass");
this.connection = factory.newConnection();
this.channel = this.connection.createChannel();
Map<String, Object> args = new HashMap<String, Object>();
args.put("x-max-priority", 60);
this.channel.queueDeclare(QUEUE_NAME, false, false, false, args);
}catch(Exception e){
System.out.println("Create Exception"+e);
}
}
public void run(){
String message;
byte[] data = null;
for(int k=this.start; k<=(this.end); k++){
message = "Message_" + k;
unixTime = System.nanoTime();
try{
this.channel.basicPublish(
"",
this.QUEUE_NAME,
new BasicProperties.Builder()
.deliveryMode(1)
.priority(k%10+1)
.build(),
message.getBytes("UTF-8")
);
}catch(Exception e){
System.out.println("New connection made"+e);
}
timeTaken = System.nanoTime() - unixTime;
totalTimeTaken += timeTaken;
if(timeTaken < minLatency){
minLatency = timeTaken;
}
if(timeTaken > maxLatency){
maxLatency = timeTaken;
}
totalRequests ++;
}
avgLatency = totalTimeTaken / totalRequests;
System.out.println("TotalReqs:" + totalRequests + "
TotalTime:" + ((float)totalTimeTaken/1000000.0) + "
MinLatency:" + ((float)minLatency/1000000.0) + " MaxLatency:"
+ ((float)maxLatency/1000000.0) + " AvgLatency:" +
((float)avgLatency/1000000.0));
try{
channel.close();
connection.close();
}catch(Exception e){
System.out.println("Close Exception");
}
}
}