Concurrent Queue
Upload multiple files simultaneously. Configure the concurrency level to control how many files upload at once.
What you should see: three files uploading at once, not all of them. Queue five or six and watch the fourth wait for a slot — that is the concurrency limit doing its job.
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<core-upload asp-upload-url="/api/upload/upload"
asp-concurrent="3"
asp-multiple="true"
asp-progress="true"
asp-auto-upload="true">
</core-upload>
<!-- Concurrency examples -->
<!-- asp-concurrent="1" -- sequential, one at a time -->
<!-- asp-concurrent="3" -- three files at once -->
<!-- asp-concurrent="5" -- five files at once -->Several files at once
asp-concurrent defaults to 1. Raising it overlaps transfers so a batch of small files finishes sooner, because each spends less time waiting for its turn rather than transferring.
More is not linearly better
Browsers cap simultaneous connections per host, so beyond that point extra uploads queue inside the browser. They also share the same upstream bandwidth: ten at once means ten slow ones instead of a few quick ones. Two to four is the range that usually helps.