Do you queue


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Do you queue

  1. 1. Do you queue? Characteristics of scalability Kevin Schroeder Technology Evangelist Zend Technologies
  2. 2. 2 •Kevin Schroeder  Technology Evangelist for Zend  Programmer  Sys Admin  Author • IBM i Programmer’s Guide to PHP • You want to do WHAT with PHP?  Race Ferraris on the weekend • My Honda has a dismal win record About me
  3. 3. 3 I blog at Follow us! (good things will happen to you)  Zend Technologies   (me!)
  4. 4. 4 Could your PHP apps benefit from being able to process data or execute asynchronously? Twtpoll results
  5. 5. 5 •Performance  Execute logic apart from the main request (asynchronicity) •Scalability  The ability to handle non-immediate logic as resources are available Why would you want to queue?
  6. 6. 6 •People often say that performance and scalability are two completely different things. This is inaccurate •Performance is the speed by which a request is executed •Scalability is the ability of that request to maintain its performance as load/infrastructure increases Performance & Scalability
  7. 7. 7 •DON’T!! •You are not Facebook •You probably won’t be •Don’t overcomplicate your problems by trying to be So how do you scale to Facebook size?
  8. 8. 8 Typical anatomy of a PHP Application | Presentation Application Control Database Access Business Logic Presentation Application Control Business Logic Presentation Bad for scala- bility!
  9. 9. 9| | Presentation Database Access Business Logic Application Control Someth ing.pht ml Someth ing.pht ml Someth ing.pht ml Someth ing.pht ml Someth ing.pht ml Someth ing.pht ml Someth ing.pht ml Someth ing.pht ml Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Someth ing.php Good for Scalability
  10. 10. 10 Defined tasks Loose coupling Resource discovery What helps make software scalable?
  11. 11. 11 The Golden Rule of Scalability “It can probably wait”
  12. 12. 12 •Pre-caching data •Data analysis •Data processing •Pre-calculating (preparing data for the next request) Data is “out of date” once it leaves the web server Immediacy is seldom necessary Asynchronous execution uses
  13. 13. 13 •A sledgehammer can hit a machine  Scalability and High Availability are yin and yang • A site that can’t keep running is not scalable • A site that can’t scale will fail (if it gets really popular) •Machines can be added and removed at will  Not “cloudy” necessarily •No single point of failure  Data exists in at least two, preferably at least three, places Characteristics
  14. 14. 14 •Waste disk space •Control usage (don’t let users do anything they want) •Pre-calculate as much as possible  Calculate and cache/store •Don’t scan large amounts of data •Keep data processing off the front end servers •Don’t just cache  Don’t let it substitute for thought  Cache hit rates can be meaningless if you have hundreds of cache hits for a request Considerations
  15. 15. 15 • Build a deployment mechanism with NO hardcoded values like directory or resource locations • Make as much as possible configurable/discoverable •Decouple/Partition  Don’t tie everything (relationships and such) into the database •Use queues/messaging  Stomp interfaces are really good for PHP – Can also use Java Bridge  Zend_Queue has several interfaces •Try to use stateless interfaces  (polling is more scalable than idle connections) Considerations
  16. 16. 16 •Use Cron /w PHP CLI (probably shouldn’t do this) •Use Gearman •Use home-grown (don’t do this) •Use pcntl_fork() (NEVER do this) •Use Zend Server Job Queue Options
  17. 17. 17 Gearman* Zend Server Job Queue Free Lightweight Open Source (mostly) language agnostic Distributed queuing Ready to go Integrates with Event Monitoring Integrates with Code Tracing Runs over a widely known protocol Load distribution can be accomplished outside of the queue Your only real options * I am not an expert on Gearman. Corrections will be taken in the spirit that they are given. Very cloud friendly For obvious reasons, I will focus on Zend Server
  18. 18. 18 •Schedule jobs in the future •Set recurring jobs •Execute immediately, as resources are available (my fav) •Utilize ZendJobQueue() Using the Zend Server Job Queue
  19. 19. 19 Job Queue Architecture – Elastic Backend Users! Web Server /w JQ Web Server /w JQ Web Server /w JQ Web Server Web Server Web Server LoadBalancer •Pros  Scale the backend as necessary  Default (easy) mechanism •Cons  Getting the job status requires using a DB
  20. 20. 20 Job Queue Architecture – Elastic Frontend Users! Web Server Web Server Web Server Web Server /w JQ Web Server /w JQ Web Server /w JQ LoadBalancer •Pros • Easy to communicate with the Job Queue server handling the job Cons • Requires you to build your own interface
  21. 21. 21 •Create a task-handling controller •Create an abstract task class  Understands the Job Queue  Self contained • If Elastic Backend: connects to localhost • If Elastic Frontend: connects to load balancer (my preferred), load balanced JQ servers manage themselves •Execute the task, have it serialize itself and send it to send to the task handler Kevin’s favorite way to implement it
  22. 22. 22  Q_Manager Handles connecting to the queue and passing results back and forth  Q_JobAbstract Abstract class that a job would be based off of  Q_Response The response from the manager when a job is queued. Contains the server name and job number  Job_Scandir The actual job that scans the directory  Job_ScandirResult An object that represents the data found Classes involved in the demo
  23. 23. 23  Create job and set data  Execute job • Job passes itself to the queue manager • Manager serializes job • Manager uses HTTP call through a load balancer to queue the job • The queue on the other end returns the job id and server name • Job ID and server name is passed to the client  Client polls the manager to get a completed job • When the job is returned pass the serialized version of the executed job Execution Flow
  24. 24. 24 Let’s write some code (no I’m not copping out with slides. We’re all told to show our work in grade scool)
  25. 25. 25 Follow us!  Zend Technologies   (me!)
  26. 26. 26 Get this information and all the examples at…
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