> On Nov 22, 2016, at 18:58 , Shawn Erickson <shaw...@gmail.com> wrote: > > Does your server speak http/2 ?
No, I don't think so. > What type of http tasks as you creating? let req = URLRequest(...) session.downloadTask(with: req) > How are throttling the number of active tasks in session(s), you say to four. I have a list of all the URLs I need to download. I start a download by popping one off the list, and setting up a downloadTask. I repeat that when a task completes successfully (in certain error cases, I put it back on in the list) and pop another and start it. To get four simultaneously, I just start four. > What does your thread count and queues look like when things go south on you? I have 30 - 50 threads, the vast majority are just 3 frames deep, stopped in __workq_kernreturn. Main thread is quite deep, with eight or so "Enqueued from…" entries. Three or four more "Queue" threads, an NSURLConnectionLoader thread, and a uikit eventfetch thread. > > -Shawn > > > On Tue, Nov 22, 2016 at 4:51 PM Rick Mann <rm...@latencyzero.com> wrote: > > > On Nov 22, 2016, at 16:47 , Shawn Erickson <shaw...@gmail.com> wrote: > > > > I am kinda curious if you can put together some example code for the > > problem. > > > > I am hitting a single URL session with 10 concurrent requests driving thru > > hundreds in a minute for small requests against the same backend. I > > throttle things using an operation queue set to 10 current operations and > > have a simple asynchronous friendly operation starting up the request and > > finishing it self when the operation competes. > > > > I have run up the concurrency as a test and not seen what you are reporting. > > > > As others note it really isn't a good idea to attempt that many concurrent > > requests in the same URL session or different session especially if hitting > > the same server. Unless the server is returning data very very slowly with > > no bandwidth limits between you and it you likely shouldn't have more then > > a handful active at once. > > Again, I hit the problem with only 4 (or with the default settings), and 5 - > 11 simultaneous URLSessions. And again, I don't have this problem at all on > iOS 9. > > I might be able to build a test case that hits our servers, but it does > require downloading thousands (perhaps hundreds) of files per session. > > > > > -Shawn > > > > > > On Tue, Nov 22, 2016 at 1:29 PM Rick Mann <rm...@latencyzero.com> wrote: > > > > > On Nov 22, 2016, at 03:23 , Quinn The Eskimo! <eski...@apple.com> wrote: > > > > > > > > > On 22 Nov 2016, at 11:17, Rick Mann <rm...@latencyzero.com> wrote: > > > > > >> I tried setting it to 4, but I still get the problem. > > > > > > What happens if you don’t modify it at all? > > > > Still get the problem. > > > > FWIW, I'm also setting .httpShouldUsePipelining to true and > > .timeoutIntervalForRequest to 3600 (necessary because the timeout isn't > > reset for each request, but rather for the whole session). I commented out > > all my adjustments and tried just the default URLSessionConfiguration, > > still the same behavior. > > > > • Aside: I was getting the default URLSessionConfiguration and setting > > these properties. Should I be getting a copy of the default instead? > > > > • I'm also worried about the frequent "A server with the specified hostname > > could not be found" errors I get. Could that be the result of attempts at > > DNS resolution failing because of too many open files, and being changed > > into a not-found error? I also get "The Internet connection appears to be > > offline". > > > > In fact, all three errors are often found interspersed throughout. > > > > • I don't understand why so many connections are opening, since I am > > currently limiting it to 4 tasks per session. It seems they're not closing > > after each use, but not getting re-used? > > > > Thanks, > > > > -- > > Rick Mann > > rm...@latencyzero.com > > > > > > > > _______________________________________________ > > Do not post admin requests to the list. They will be ignored. > > Macnetworkprog mailing list (Macnetworkprog@lists.apple.com) > > Help/Unsubscribe/Update your Subscription: > > https://lists.apple.com/mailman/options/macnetworkprog/shawnce%40gmail.com > > > > This email sent to shaw...@gmail.com > > > -- > Rick Mann > rm...@latencyzero.com > > -- Rick Mann rm...@latencyzero.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Macnetworkprog mailing list (Macnetworkprog@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/macnetworkprog/archive%40mail-archive.com This email sent to arch...@mail-archive.com
