zConcurrentModificationException

[Scorpius 144]

Here's a snippet demonstrating how I worked around the ConcurrentModificationException that gets thrown due to multi-threaded scripts attempting to add/remove something to the same list at the same time causing the entire script to freeze.

 

This should work with any other data type that produces the same behaviour

// Our dummy hot list that throws ConcurrentModificationException when we try to add/remove something to/from it
List<String> myHotList = new ArrayList<String>();

// Assume this gets called wherever
public not-so-static void zFunction()
{
    int attempts = AddToList(myHotList, "zHotString");
    System.out.println("Added new hot string in " + attempts + " attempts");
    
    attempts = RemoveFromList(myHotList, "zHotString");
    System.out.println("Removed old but still hot string in " + attempts + " attempts");
}

// Our magic functions
private int AddToList(List<String> zList, String new_string)
{
    int attempts = 0;
    while(true)
    {
        try
        {
            attempts++;
            zList.add(new_string);
            break;
        }
        catch(Exception | Error e)
        {
        }
        try
        {
            Thread.sleep(3333);
        }
        catch(Exception | Error e)
        {
        }
    }
    return attempts;
}

private int RemoveFromList(List<String> zList, String old_but_hot_string)
{
    int attempts = 0;
    while(true)
    {
        try
        {
            attempts++;
            zList.remove(old_but_hot_string);
            break;
        }
        catch(Exception | Error e)
        {
        }
        try
        {
            Thread.sleep(3333);
        }
        catch(Exception | Error e)
        {
        }
    }
    return attempts;
}

[dQw4w9WgXcQ 184]

what the fuck

[Scorpius 144]

what the fuck

It actually gets the bot working =/

[GetBig 1]

https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/CopyOnWriteArrayList.html

There, problem solved 

[Dorkinator 64]

You should lose your scripter rank for this.

[dQw4w9WgXcQ 184]

hi mad

[GetBig 1]

how did u pass a scripting test if u think this is how concurrency should be handled, not even trying 2 be mean

[Scorpius 144]

https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/CopyOnWriteArrayList.html

 

There, problem solved 

Are there other similar classes for other data types?

[hexagon 18]

https://docs.oracle.com/javase/tutorial/essential/concurrency/sync.html

[Scorpius 144]

https://docs.oracle.com/javase/tutorial/essential/concurrency/sync.html

Cheers!