Api and threading issue?

james1bow · Sunday, 10:34 am

i have been working on a rather large plugin and i NEED to implement threading. i have been driving myself crazy with an issue tho. it seems to me that if i create a new thread the API creates hundreds of new threads. i have done some testing and i dont no think it is my code. any input would be helpful.

Java

// Init player method
public void initPlayer(Player player){
        if(rpCore.getConfig().getDevConfig().getMultiThreadEnabled()){
            Thread initThread = new Thread(new InitPlayer(rpCore, player, rpCore.getConfig().getDevConfig().getMultiThreadEnabled()));
            initThread.start();
        }else{
            new InitPlayer(rpCore, player, rpCore.getConfig().getDevConfig().getMultiThreadEnabled());
        }

    }

Java

//class init player called from Init method
public InitPlayer(RPCore rpCore, Player player, Boolean multiThreadEnable) {
        this.rpCore = rpCore;
        this.player = player;
        this.multiThreadEnable = multiThreadEnable;
        playerMenus = new HashMap<>();
        implementingMenuElement = new HashMap<>();
        implementingSettingsElement = new HashMap<>();
        if(!multiThreadEnable){
            println("Running InitPlayer NON-Threaded",10);
            initPlayerSettings();
        }
    }

    @Override
    public void run(){
        println("Running InitPlayer Threaded "+Thread.currentThread().getName(),10);
        initPlayerSettings();
    }

    private void initPlayerSettings(){
        HashMap<String, String> settings = rpCore.getDatabaseManager().getSettingsDBController().getPlayerSettings(player.getUID());
        ps = new PlayerSettings(rpCore);
        ps.setBackgroundName(settings.get("backgroundName"));
        ps.setBackgroundImage(rpCore.getAssets().getImages().getImageByName(settings.get("backgroundName")));
        ps.setHeaderFont(Font.valueOf(settings.get("headerFont")));
        ps.setHeaderFontSize(Float.parseFloat(settings.get("headerFontSize")));
        ps.setHeaderFontColor(Integer.parseInt(settings.get("headerFontColor")));
        ps.setTextFont(Font.valueOf(settings.get("textFont")));
        ps.setTextFontSize(Float.parseFloat(settings.get("textFontSize")));
        ps.setTextFontColor(Integer.parseInt(settings.get("textFontColor")));
        ps.setBorderColor(Integer.parseInt(settings.get("borderColor")));
        ps.setBorderSize(Float.parseFloat(settings.get("borderSize")));
        ps.setButtonBackgroundColor(Integer.parseInt(settings.get("buttonBackgroundColor")));
        ps.setButtonBorderColor(Integer.parseInt(settings.get("buttonBorderColor")));
        ps.setButtonFontColor(Integer.parseInt(settings.get("buttonFontColor")));
        ps.setButtonFontSize(Float.parseFloat(settings.get("buttonFontSize")));
        ps.setButtonFont(Font.valueOf(settings.get("buttonFont")));
        ps.setButtonBorderSize(Float.parseFloat(settings.get("buttonBorderSize")));
        ps.setMenuFont(Font.valueOf(settings.get("menuFont")));
        ps.setMenuFontColor(Integer.parseInt(settings.get("menuFontColor")));
        ps.setMenuFontSize(Float.parseFloat(settings.get("menuFontSize")));
        ps.setInteractionKey(Key.valueOf(settings.get("interactionKey")));
        ps.setInteractionOptionKey(Key.valueOf(settings.get("interactionOptionKey")));
        ps.setHideMenuOnExit(Boolean.parseBoolean(settings.get("hideMenuOnExit")));
        ps.setHideInfoTextOnExit(Boolean.parseBoolean(settings.get("hideInfoTextOnExit")));
        ps.setMainMenuPositionX(Float.parseFloat(settings.get("mainMenuPositionX")));
        ps.setMainMenuPositionY(Float.parseFloat(settings.get("mainMenuPositionY")));
        ps.setMainMenuSizeX(Float.parseFloat(settings.get("mainMenuSizeX")));
        ps.setMainMenuSizeY(Float.parseFloat(settings.get("mainMenuSizeY")));
        ps.setMainPanelPositionX(Float.parseFloat(settings.get("mainPanelPositionX")));
        ps.setMainPanelPositionY(Float.parseFloat(settings.get("mainPanelPositionY")));
        ps.setMainPanelSizeX(Float.parseFloat(settings.get("mainPanelSizeX")));
        ps.setMainPanelSizeY(Float.parseFloat(settings.get("mainPanelSizeY")));

        if(rpCore.getConfig().getBaseConfig().getGeneralConfig().getDebugTextEnabled()) {
            ps.debug(settings);
        }

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Java

//ps.debug method
println("[RPCore/PlayerSettings]" , 9);
        for (Map.Entry<String, String> entry : settings.entrySet()) {
            String key = entry.getKey();
            String value = entry.getValue();
            println("\t "+key+": -> "+value, 14);
        }

logs to show what i think is an issue

Threaded threaded console output.txt

NON-Threaded non threaded consol output.txt

Again it may be me but o do not believe it is.

Bamse · Sunday, 3:19 pm

Same thing i se on my plugin too. I use a background thread to move a vehicle along a route. First i tried with Timer and well worked well, but limited to a single vehicle. Latter i use proper thread to move many simultaneous vehicle, and when i use my thread i see a lot of messages like:

Code

Create new JNIEnv (handle: 1379188631568, thread: 98)
[Java] [DEBUG] FerryTask id=1 : Trigger MoveToEvent = (1886.0, 1889.0) step=2 stepAtribute=2
Create new JNIEnv (handle: 1379188631568, thread: 99)
Create new JNIEnv (handle: 1379188631568, thread: 100)
[Java] [DEBUG] Vehicle: Move from (1900.171, 90.09956, 1920.7201) to (1886.0, 90.1, 1889.0) for task 1 step atribute=2
Create new JNIEnv (handle: 1379188631568, thread: 101)
Create new JNIEnv (handle: 1379188631568, thread: 104)
[Java] [DEBUG] OnCostEvent: distance=34.74165 , cost=13.89666, total_cost=34.80208
Create new JNIEnv (handle: 1379188631568, thread: 106)
[Java] [DEBUG] FerryTask id=1 : Trigger MoveToEvent = (1862.0, 1847.0) step=3 stepAtribute=3
Create new JNIEnv (handle: 1379188631568, thread: 107)
Create new JNIEnv (handle: 1379188631568, thread: 108)
[Java] [DEBUG] Vehicle: Move from (1888.9164, 90.09978, 1895.47) to (1862.0, 90.1, 1847.0) for task 1 step atribute=3
Create new JNIEnv (handle: 1379188631568, thread: 109)
Create new JNIEnv (handle: 1379188631568, thread: 112)
[Java] [DEBUG] OnCostEvent: distance=55.44213 , cost=22.176851, total_cost=56.978928
Create new JNIEnv (handle: 1379188631568, thread: 114)
[Java] [DEBUG] FerryTask id=1 : Trigger MoveToEvent = (1840.0, 1809.0) step=4 stepAtribute=4
Create new JNIEnv (handle: 1379188631568, thread: 115)
Create new JNIEnv (handle: 1379188631568, thread: 116)
[Java] [DEBUG] Vehicle: Move from (1867.4291, 90.09984, 1856.7207) to (1840.0, 90.1, 1809.0) for task 1 step atribute=4
Create new JNIEnv (handle: 1379188631568, thread: 117)
Create new JNIEnv (handle: 1379188631568, thread: 120)

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On java side :

Java

 // Executor service for FerryTasks
public static ExecutorService executor = Executors.newFixedThreadPool(10); // max 10 simultaneous vehicle moving

// This is class who run in background and generate moveEvents custom event
public class FerryRunTask implements Runnable {
...
    FerryMoveToEvent e = ...
    plugin.triggerEvent(e);
...
}


// Start background thread who generate custom Events

...
 FerryRunTask task = new FerryRunTask(player,vehicle,sourceDockName,destination);
        
 // Start background move thread
 if (FerryConfig.FERRY_USE_API_TIMER==true) {    // Using API Timer, just 1 vehicle moving
            Timer timer = new Timer(0f,0f, 0,task);
            timer.start();
 } else {    // start thread - can have many vehicle running simultaneous (10 in this case)
            executor.execute(task);

 }
...

// Actual move of vehicle

// Custom ferry event method. This is triggered when ship must me moved in a new position 
@EventMethod
public void onFerryMoveToEvent(FerryMoveToEvent evt) {    // Custom ferry event method. This is triggered when ship must me moved in a new position 
...
}

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And BTW when i use Custom Event

Java

// Base class for all FerryEvents
public class FerryEvent extends Event {
private Player player;
private Vehicle vehicle;
...
}

public class FerryMoveToEvent extends FerryEvent {
    private long taskID=-1;
    private Vector2f moveLocation;
    private FerryMoveType moveType;
...
}

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And when i used custom event and register this event for listening i get in log for every custom event:

Code

[Java] -> Event: bamse.rw.ferry.events.FerryMoveToEvent
[ERROR] [09:08:30] Java RegisterEvent - Event not found: Events.FerryMoveToEvent
UnityEngine.Debug:LogError(Object)
RisingWorld.PluginAPI.PluginEventHandler:OnRegisterEvent(IntPtr, JObject, JString) (at C:/GitLab-Runner/builds/jxpAq3Km/2/jiw-games/rising-world/Assets/Scripts/PluginAPI/PluginEventHandler.cs:258)

red51 · 2025-11-10T15:52:37+01:00

Thanks for bringing this to my attention! I can confirm that this is a bug in the API: the native JNI interface is only valid in the current thread, or more precisely, each thread requires a separate JNI env pointer (this is a restriction from JNI). When accessing an API method which communicates with the native side (which is the case for most methods and objects) from another thread, the game creates a new JNIenv pointer for that thread. Unfortunately it does not cache this pointer, so a new pointer will be created for subsequent accesses. This is quite problematic and can result in a number of issues.

I will prepare a fix for that... do you only run your plugins on dedicated servers atm?

james1bow · 2025-11-10T16:24:38+01:00

yes I only run them on dedicated servers. I never test in single player or p2p

Bamse · 2025-11-10T18:05:07+01:00

i tested too only on dedicated server.

I see this behavior some time ago and suspected is something with context switch of thread but i don't reported yet as possible problem and almost forgot about it. Thx james1bow to bring this to attention!

red51 · 2025-11-10T22:00:14+01:00

Just to avoid misunderstandings: the game does not spawn new threads or something like that. It just creates a new JNIenv pointer everytime you access an API method from a new thread (that was not created by the game). It's a waste of resources ofc and could also result in other issues, so it's definitely a more serious bug.

Unfortunately there are no more hotfixes planned, but I'll prepare at least a hotfix for the server which fixes this bug, would that work for you? The next regular update (which also contains the fix) should still be ready this year

Bamse · 2025-11-11T01:16:38+01:00

About error from log when i use custom events? It seems is just a wrong message for custom events. All event are fired and work correctly.

Code

[Java] -> Event: bamse.rw.ferry.events.FerryMoveToEvent
[ERROR] [09:08:30] Java RegisterEvent - Event not found: Events.FerryMoveToEvent
UnityEngine.Debug:LogError(Object)
RisingWorld.PluginAPI.PluginEventHandler:OnRegisterEvent(IntPtr, JObject, JString) (at C:/GitLab-Runner/builds/jxpAq3Km/2/jiw-games/rising-world/Assets/Scripts/PluginAPI/PluginEventHandler.cs:258)

james1bow · 2025-11-11T02:50:51+01:00

Quote from red51

Just to avoid misunderstandings: the game does not spawn new threads or something like that. It just creates a new JNIenv pointer everytime you access an API method from a new thread (that was not created by the game). It's a waste of resources ofc and could also result in other issues, so it's definitely a more serious bug.

Unfortunately there are no more hotfixes planned, but I'll prepare at least a hotfix for the server which fixes this bug, would that work for you? The next regular update (which also contains the fix) should still be ready this year

whatever works for you. I've added a sett8ng for now to disable multi threads in my plugin so really no rush. AS long as its not really creating hundreds of threads lol.

Bamse · 2025-11-11T09:10:50+01:00

Same for me. i have too a switch to use Timer or native thread. No hurry.

Participate now!