Hello! On Thu, Mar 14, 2013 at 07:07:20PM -0700, Jay Oster wrote:
[...] > The access log has 10,000 lines total (i.e. two of these tests with 5,000 > concurrent connections), and when I sort by upstream_response_time, I get a > log with the first 140 lines having about 1s on the upstream_response_time, > and the remaining 9,860 lines show 700ms and less. Here's a snippet showing > the strangeness, starting with line numbers: > > > 1: 127.0.0.1 - - [14/Mar/2013:17:37:21 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 1.027 1.026 234 83 > 2: 127.0.0.1 - - [14/Mar/2013:17:37:21 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 1.027 1.026 234 83 > 3: 127.0.0.1 - - [14/Mar/2013:17:37:21 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 1.026 1.025 234 83 > ... > 138: 127.0.0.1 - - [14/Mar/2013:17:57:18 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 1.000 0.999 234 81 > 139: 127.0.0.1 - - [14/Mar/2013:17:57:18 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 0.999 0.999 234 81 > 140: 127.0.0.1 - - [14/Mar/2013:17:57:18 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 0.999 0.999 234 81 > 141: 127.0.0.1 - - [14/Mar/2013:17:37:21 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 0.708 0.568 234 83 > 142: 127.0.0.1 - - [14/Mar/2013:17:37:21 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 0.708 0.568 234 83 > 143: 127.0.0.1 - - [14/Mar/2013:17:37:21 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 0.708 0.568 234 83 > ... > 9998: 127.0.0.1 - - [14/Mar/2013:17:57:16 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 0.142 0.005 234 81 > 9999: 127.0.0.1 - - [14/Mar/2013:17:57:16 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 0.142 0.005 234 81 > 10000: 127.0.0.1 - - [14/Mar/2013:17:57:16 -0700] "GET /time/0 HTTP/1.0" > 200 19 "-" "ApacheBench/2.3" 0.122 0.002 234 81 > > > > The upstream_response_time difference between line 140 and 141 is nearly > 500ms! The total request_time also displays an interesting gap of almost > 300ms. What's going on here? I would suggests there are packet loss and retransmits for some reason. Try tcpdump'ing traffic between nginx and backends to see what goes on in details. -- Maxim Dounin http://nginx.org/en/donation.html _______________________________________________ nginx mailing list nginx@nginx.org http://mailman.nginx.org/mailman/listinfo/nginx