Implementation of a parallel web proxy server with caching

1. Implementation of a parallel web proxy server with caching Presented by: KaushikChoudhary

2. Outline • Introduction • Design Challenges • Design Challenges - Solutions • Implementation • Experimental Setup • Results

3. Introduction • What is an HTTP/1.0 web-proxy? • Already covered by others. • How does it work? • Already covered by others. • What is a parallel web proxy with caching? • Already covered by others.

4. Outline • Introduction • Design Challenges • Design Challenges - Solutions • Implementation • Experimental Setup • Results

5. Design Challenges • Dozens of open-source implementations available online to take “inspiration” from. • System calls • Parallelism • Efficient Cache

6. Design Challenges – System calls

7. Design Challenges – Parallelism • The pseudo-code in the project description says “Spawn a worker thread to handle the connection” • What if there were a 100 connection requests? • If there is a request queue, how do threads atomically access this queue?

8. Design Challenges – Caching • Size of cache? • Eviction policy. • Atomic and efficient access to Cache.

9. Outline • Introduction • Design Challenges • Design Challenges - Solutions • Implementation • Experimental Setup • Results

10. Design Challenges – Parallelism solutions • If there were a 100 requests, create a pre-determined number of threads and assign a request as task. • Use locks to access the task queue. • Atomic and efficient access to Cache.

11. Design Challenges – Caching solutions • Currently stores at most 20 responses (web pages) [TODO – limit size] • Eviction policy used - LRU. • Store the pages and timestamps in a doubly linked-list, make a node a head when accessed, use a hashmap to index elements of this list.

12. Outline • Introduction • Design Challenges • Design Challenges - Solutions • Implementation • Experimental Setup • Results

13. Implementation • Used open-source object oriented design from “http://www.home.no/adiv/index.htm” • Implemented pthreads and openmp versions for parallelism. • Implemented cache as described above.

14. Outline • Introduction • Design Challenges • Design Challenges - Solutions • Implementation • Experimental Setup • Results

15. Experimental Setup • Created command line scripts to open 30 distinct non-https websites (google-chrome commandline). • Distinct websites avoids interference from browser cache. • Measured total time to serve all requests in threadless, different pthreadsversions and openmpversion of the code. • Conducted experiments on two machines (Core i5 2.4 GHz, 4GB RAM (desktop) and Core i5 2.67 GHz, 8GB RAM)(laptop).

16. Outline • Introduction • Design Challenges • Design Challenges - Solutions • Implementation • Experimental Setup • Results

17. Results – Access times (no-cache)

18. Results – Speedup (desktop)

19. Thank you!