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I am using Volley library in Android, I want to know what is maximum size of queue is allowed using Volley library. There is nothing I found related to this. As I know you need to add the network request to the queue but I don't know what is maximum size of this that I can put it on queue parallel.

RequestQueue requestQueue = Volley.newRequestQueue(this);
.... // block of code
requestQueue.add(jsonObjectRequest);
Patrick
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Bot
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1 Answers1

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You are probably confusing 2 things:

  • wating queue size
  • max parallel network requests

For waiting queue size:

/** The queue of requests that are actually going out to the network. */
private final PriorityBlockingQueue<Request<?>> mNetworkQueue =
    new PriorityBlockingQueue<Request<?>>();

Volley uses a PriorityBlockingQueue which itself uses a PriorityQueue with a initial capacity of 11, but will automatically grow, so there should be no reasonable limit.

private static final int DEFAULT_INITIAL_CAPACITY = 11;
...
public PriorityQueue() {
    this(DEFAULT_INITIAL_CAPACITY, null);
}

For max parallel network requests:

RequestQueue requestQueue = Volley.newRequestQueue(this);

will call

RequestQueue queue = new RequestQueue(new DiskBasedCache(cacheDir), network);

and this calls

public RequestQueue(Cache cache, Network network) {
        this(cache, network, DEFAULT_NETWORK_THREAD_POOL_SIZE);
    }

and DEFAULT_NETWORK_THREAD_POOL_SIZE is

private static final int DEFAULT_NETWORK_THREAD_POOL_SIZE = 4;

So by default there are 4 concurrent threads handling the requests (so max 4 request at the same time).

Waiting queue size is Integer.MAX ie. basically limitless; while max parallel network requests are 4, which can be changed with the RequestQueue constructor.

Patrick
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  • Thanks, so once four requests are running then other have to wait until they finished. can you confirm this also ? – Bot Mar 30 '14 at 13:15
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    Yes, but you can customize the threadpool size yourself by calling public RequestQueue(Cache cache, Network network, int threadPoolSize) – Patrick Mar 30 '14 at 13:16
  • and I call here like `requestQueue.add(jsonObjectRequest);` that can be maximum to `INTEGER.MAX_VALUE (2^32)` but they all will be in waiting until they get a chance . Is it correct ? – Bot Mar 30 '14 at 13:18
  • I'm sorry I was wrong there upon inspecting the code of the queue the capcity is set to 11 not INTEGER.MAX_VALUE - see my updated answer – Patrick Mar 30 '14 at 13:53
  • Ah, I see thanks :) so more than 11 requests can not add into the queue , right ? – Bot Mar 30 '14 at 14:00
  • Not tested, but according to the source code: yes :) – Patrick Mar 30 '14 at 14:15
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    Corrent me if I am wrong, or maybe it has been updated. According to recent `PriorityBlockingQueue` source, the `DEFAULT_INITIAL_CAPACITY` is just "initial". It will grow automatically as you call `request.add()` if the queue is already full. Calling the `add()` will call `queue.offer()` and `queue.tryGrow()` – CallMeLaNN Mar 18 '16 at 18:46
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    @CallMeLaNN you are correct, a `PriorityBlockingQueue` which uses a `PriorityQueue` is a self growing data structure, I will change my answer – Patrick Apr 05 '18 at 15:25