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Leland Barton avatar Server

Nginx Keep Alive: Simultaneous SSL Handshakes Taking 25s

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Leland Barton

Thanks for reading :)

This is a super difficult issue and would like to receive any ideas or suggestions to figure out this issue.

Problem: The application on a user logging in initiates ~20 api requests in parallel. The first request will do the SSL handshake and then around the 10th to 13th request, I see two requests initiate the SSL handshake at the same time with each handshake getting stuck and taking over 25 seconds to repeat. The issue manifests for users as a 30 second login.

Setup: I have a setup with hardware based load balancer and about 8 nginx nodes that reverse proxy for a java application running on the same node. FE is a SPA, and all traffic flowing through nginx is dynamic content.

Additional Details

  • Tweaking the keepalive from 65s to 10s reduced the total SSL handshake time from >30s (which is the FE timeout) to 25s, so the issue is related to keepalive in some way.
  • This issue was only present on FF, and has now spread to safari.
  • Upgraded nginx to latest LTS
  • Load balancer is distributing requests round robin.
  • Nginx logs do omit any mention of the issue.
  • The api requests are ordered, and usually affect 2 of the same 3 requests.
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Ivan Shatsky avatar
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Ivan Shatsky
Read the [HTTPS server optimization](http://nginx.org/en/docs/http/configuring_https_servers.html#optimization) chapter from the official "Configuring HTTPS servers" documentation page. Take a look at the [`ssl_session_cache`](http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_session_cache) and [`ssl_session_timeout`](http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_session_timeout) directives. Maybe it could be of some help, try to tweak those parameters.
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