Avatar Mike Noordermeer Some notes on Tomcat connector performance

Mike Noordermeer | Published April 7, 2012 |

In my last blog post, I mentioned that there is a performance difference between Tomcat’s APR and BIO / default connector. In this blog I did a quick comparison of these connectors.

Tomcat ships with 3 HTTP(s) connectors:

  • Blocking IO (org.apache.coyote.Http11Protocol): this is the default and most stable connector.
  • Non-blocking IO (org.apache.coyote.Http11NioProtocol): this is a non-blocking IO connector, which you will need for Comet/WebSockets and should offer slightly better performance in most cases.
  • APR (org.apache.coyote.Http11AprProtocol): this connector uses Apache Portable Runtime and OpenSSL instead of their Java counterparts. Because of this, performance is generally better, especially when using SSL.

To do a quick comparison of these connectors, I used ApacheBench and ran some simulated load tests (100k requests, 100 concurrent requests) on the various connectors. The page requested was a simple JSP that displayed the current date. Tomcat 7.0.26 ran on Windows (yeah, really, it can run on Windows), and to compare with the Apache HTTPD and PHP I also did a run on a simple PHP page displaying the current date on Apache 2.2.16 (on Linux). Tests were done using HTTP and HTTPS, with and without keep-alive. The results are by no means scientifically significant, but give a general idea on the performance differences. YMMV, so please run your own benchmarks on your own applications (and create a more intelligent test scenario, using for instance Apache JMeter).

Connector HTTP HTTP KEEP-ALIVE HTTPS HTTPS KEEP-ALIVE
BIO 7341 14809 142 4036
NIO 3816 10257 - -
APR 8214 15062 240 11121
Apache HTTPD 8780 15880 236 4056

Numbers are in request per second, higher is better. Due to some ApacheBench bug I could not test NIO over HTTPS. Some conclusions we can draw from these results:

  • Apache Tomcat performs on a level comparable to Apache HTTPD. This is at least the case for dynamic requests, but I have seen similar results for static requests.
  • When using SSL: use keep-alive, unless you have a specific reason not to.
  • When using SSL on Tomcat: use APR.
  • Don’t expect NIO to give a better performance than BIO out of the box. Benchmark, benchmark, benchmark.
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