Hi,

i'm developing an app which download map tiles around different places in a city. To do this, i have one thread for each place in which i select the tiles and create a thread to download each.

Well, the question is how to avoid creating a thread for a tile that already exists in the thread pool.

Should not just check if the file exists, since it is possible that the thread for that tile already exists (other place already need that tile) but the file has not been created-

Any idea? Thanks