Will it be a problem if I do not complete an ActionBlock

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I am trying to use action block to execute some tasks. My question is when the CreateActionBlock() method finishes, the ActionBlock is still processing the data. Since the method is returned and I do not have a way to call actionBlock.Complete(). Will it cause any problems if I run this CreateActionBlock() thousand times? Will there be thousand of actionBlocks forever in the memory or they will be GC'ed after the 5 inputs processed?

private static async Task Dequeue(string content)
{
    Console.WriteLine("The string is " + content);
    await Task.Delay(10000);
}

public static void CreateActionBlock()
{
    var actionBlock = new ActionBlock<string>(
        (e) => Dequeue(e),
        new ExecutionDataflowBlockOptions()
        {
            BoundedCapacity = 5,
            MaxDegreeOfParallelism = 1
        });

    for (int i = 0; i < 5; i++)
    {
        actionBlock.Post(i.ToString());
    }
}
tpl-dataflow async-await c#
1 Answers

A dataflow block is eligible for garbage collection as soon as its input queue has been emptied, and it is currently idle. Below is an example that demonstrates this behavior:

var weakReference = InnerMethod();
for (int i = 1; i <= 10; i++)
{
    Thread.Sleep(100);
    GC.Collect();
    Console.WriteLine($"IsAlive: {weakReference.IsAlive}");
}

WeakReference InnerMethod()
{
    var block = new ActionBlock<int>(n =>
    {
        Thread.Sleep(200);
        Console.WriteLine($"Processed: {n}");
    });
    block.Post(1); block.Post(2); block.Post(3);
    return new WeakReference(block);
}

Output:

IsAlive: True
Processed: 1
IsAlive: True
IsAlive: True
Processed: 2
IsAlive: True
IsAlive: True
Processed: 3
IsAlive: False
IsAlive: False
IsAlive: False
IsAlive: False
IsAlive: False

(Try it on Fiddle)

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