Description
The following is describing the http download.
We can limit the concurrent task num by the max-concurrent-downloads option. However if the checksum option is added to verify the files, the task is considered "downloading" in the verifying phrase. What's more, only one file is calculated checksum at one time.
So imagine this: We set max-concurrent-downloads to 10 and download 100 same big files. The first 10 tasks are fine. But when they complete downloading at almost the same time, no tasks will be downloaded now. Instead, only 1 download-completed task starts verifying, which makes a big bandwidth waste.
Thus, I suggest not counting these download-completed tasks into the concurrent-downloading number. At least add an option to let the users decide.