Thank you very much for clearing this out. All I need to do is "limit_req_log_level warn;" and then I see limits as warn-logs and delaying as info, and hence I only view warn+ levels, it is omitted from the logfile completely.
--- Med venlig hilsen / Best Regards Stephan Ryer Møller Partner & CTO inMobile ApS Axel Kiers Vej 18L DK-8270 Højbjerg Dir. +45 82 82 66 92 E-mail: s...@inmobile.dk Web: www.inmobile.dk Tel: +45 88 33 66 99 2017-11-20 14:01 GMT+01:00 Maxim Dounin <mdou...@mdounin.ru>: > Hello! > > On Mon, Nov 20, 2017 at 11:33:26AM +0100, Stephan Ryer wrote: > > > We are using nginx as a proxy server in front of our IIS servers. > > > > We have a client who needs to call us up to 200 times per second. Due to > > the roundtrip-time, 16 simultanious connections are opened from the > client > > and each connection is used independently to send a https request, wait > for > > x ms and then send again. > > > > I have been doing some tests and looked into the throttle logic in the > > nginx-code. It seems that when setting request limit to 200/sec it is > > actually interpreted as “minimum 5ms per call” in the code. If we > receive 2 > > calls at the same time, the warning log will show an “excess”-message and > > the call will be delayed to ensure a minimum of 5ms between the calls.. > > (and if no burst is set, it will be an error message in the log and an > > error will be returned to the client) > > > > We have set burst to 20 meaning, that when our client only sends 1 > request > > at a time per connection, he will never get an error reply from nginx, > > instead nginx just delays the call. I conclude that this is by design. > > Yes, the code counts average request rate, and if it sees two > requests with just 1ms between them the averate rate will be 1000 > requests per second. This is more than what is allowed, and hence > nginx will either delay the second request (unless configured with > "nodelay"), or will reject it if the configured burst size is > reached. > > > The issue, however, is that a client using multiple connections naturally > > often wont be able to time the calls between each connection. And even > > though our burst has been set to 20, our log is spawned by > warning-messages > > which I do not think should be a warning at all. There is a difference > > between sending 2 calls at the same time and sending a total of 201 > > requests within a second, the latter being the only case I would expect > to > > be logged as a warning. > > If you are not happy with log levels used, you can easily tune > them using the limit_req_log_level directive. See > http://nginx.org/r/limit_req_log_level for details. > > Note well that given the use case description, you probably don't > need requests to be delayed at all, so consider using "limit_req > .. nodelay;". It will avoid delaying logic altogether, thus > allowing as many requests as burst permits. > > > Instead of calculating the throttling by simply looking at the last call > > time and calculate a minimum timespan between last call and current > call, I > > would like the logic to be that nginx keeps a counter of the number of > > requests withing the current second, and when the second expires and a > new > > seconds exists, the counter Is reset. > > This approach is not scalable. For example, it won't allow to > configure a limit of 1 request per minute. Moreover, it can > easily allow more requests in a single second than configured - > for example, a client can do 200 requests at 0.999 and additional > 200 requests at 1.000. According to your algorithm, this is > allowed, yet it 400 requests in just 2 milliseconds. > > The current implementation is much more robust, and it can be > configured for various use cases. In particular, if you want to > maintain limit of 200 requests per second and want to tolerate > cases when a client does all requests allowed within a second at > the same time, consider: > > limit_req_zone $binary_remote_addr zone=one:10m rate=200r/s; > limit_req zone=one burst=200 nodelay; > > This will switch off delays as already suggested above, and will > allow burst of up to 200 requests - that is, a client is allowed > to do all 200 requests when a second starts. (If you really want > to allow the case with 400 requests in 2 milliseconds as described > above, consider using burst=400.) > > -- > Maxim Dounin > http://mdounin.ru/ > _______________________________________________ > nginx mailing list > nginx@nginx.org > http://mailman.nginx.org/mailman/listinfo/nginx
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