[SOLVED] 1.19.2 MySQL Query in parallel Thread and MultiThread in Maincraft

[andreybadrey]

Hi guys, my Java is BAD, and my English is verry BAD... Therefore, what I will write may not be clear, but I really ask you to try to figure it out and help me if someone knows an alternative or has already done something like this.

 

I am having the following problem with my mod:

There is a game store in the mod, how is it? Its alpha version, which will be improved from the current state... And this store is working properly... But, when buying from the store, the entire server stops at the moment the item is received from the store. The reason for this is one thread (Main Thread).

Now the purchase code works like this:

1) By pressing the key, GUI opens, information from the player's balance database is loaded into the GUI;

2) When you click on the purchase button, a packet is sent to the server with information that the player pressed the button

3) The server, having received the packet, makes a request to the database with a balance check. If the balance allows, the server issues the item to the player, makes a database query, writing the new balance.

I noticed that at the time of requests to the database, the server just sleeps. It stops generating ticks until it receives a response from the database. If you spam multiple clicks on the button, then you can observe a complete stop of the world, at the time of loading requests to the database. As far as I realized myself in Java, I understand that the reason for all this is: the sequence of code execution in the main thread, all operations are performed strictly in order ...

So, in order to fix this, based on my knowledge, I assume that you need to move database queries to a separate thread ... What is a thread and how to create it, I know a little, but very little. Of course, I will pump my knowledge in this direction.

 

But I would like to know from you:

1) Where should the new thread be written?

2) Safe syntax for opening a stream, and in which part of the code

3) Methods for transferring information from the second stream to the main one

 

I will be glad if you at least point to actual examples on the github in which this is practiced. 

Due to my limited knowledge of languages, I experience some difficulties in finding information. I will be glad for any help

GitHub

Edited August 20, 2023 by andreybadrey

[andreybadrey]

In general, as always, I independently found a solution

in fact, the topic of multithreading turned out to be very simple to understand and apply in minecraft

The point is to output each server action to a separate thread, of course, where possible and safe

For those who are interested, I am attaching my first multithread model

GITHUB

On the example of using packages, I brought each server action to a separate thread through a class with inheritance of the Thread class

class MyThread extends Thread { 

 

   @Override
   public void run() {

         any code

    }

}

Having trouble defining NetworkEvent.Context.  To define it and pass it to a new thread, I defined a static object in the package class

public class ByeAppleC2SPacket {
    public static NetworkEvent.Context val;
    public ByeAppleC2SPacket() {}

}

define a variable(object) val in the handler method and Starting the second thread

public boolean handle(Supplier<NetworkEvent.Context> supplier) {
   NetworkEvent.Context context = supplier.get();
   context.enqueueWork(() -> {
   val = context;
   MyThread myThread = new MyThread();
   myThread.start();
   });
  return true;
}

Now in a new thread, we can perform actions on the player through ByeAppleC2SPacket.val.getSender()

Also in the stream method run() we can start new threads

as a result, after performing each action in a new thread, we give a minimum drawdown on the TPS server and speed up the mod tenfold

Before using this model, the code provided in the github gave a huge drawdown of the TPS, and caused the server to crash. Now when spamming at 10 packets per second, and with three operations per packet: Request balance, give an item, update the balance. All operations are parallelized into separate threads, and do not slow down the server

Use this if you are interested ... I will ask experienced developers for feedback ...