Gearman: A Job Server to Scale

Brief introduction to the gearman job server.

Transcript

1. A Job Server to Scale By Mike Willbanks Software Engineering Manager CaringBridge MinneBar April 7, 2012
2. 2 •Talk  Slides will be online later! •Me  Software Engineering Manager at CaringBridge  MNPHP Organizer  Open Source Contributor (Zend Framework and various others)  Where you can find me: • Twitter: mwillbanks G+: Mike Willbanks • IRC (freenode): mwillbanks Blog: http://blog.digitalstruct.com • GitHub: https://github.com/mwillbanks Housekeeping…
3. 3 • What is Gearman  Yeah yeah… • Main Concepts  How it really works • Quick Start  Get it up and running and start playing. • The Details  How can it be a tech talk without details? • Some use cases  How you might use it. • Questions  Although you can bring them up at anytime! Agenda
4. What is Gearman? Official Statement What the hell it means Visual understanding Platforms
5. 5 “Gearman provides a generic application framework to farm out work to other machines or processes that are better suited to do the work. It allows you to do work in parallel, to load balance processing, and to call functions between languages.” Official Statement
6. 6 •Gearman consists of a daemon, client and worker  At the core, they are simply small programs. •The daemon handles the negotiation of work  Workers and Clients •The worker does the work •The client requests work to be done What The Hell? Tell me!
7. 7 In Pictures
8. 8 •Gearman works on linux •API implementations available  PHP  Perl  Java  Ruby  Python Platforms
9. Main Concepts Client -> Daemon -> Worker communication Distributed Model
10. 10 Client -> Daemon -> Worker communication
11. 11 Distributed Model
12. Quick Start Installation Simple Bash Example PHP Related (sorry, I’m all about the PHP)
13. 13 •Head to gearman.org •Click Download •Click on the LaunchPad download •Download the Binary •Unpack the binary •./configure && make && make install •Bam! You’re off!  For more advanced configuration see ./configure –help •Starting  gearmand -d Installation
14. 14 •Starting the Daemon  gearmand –d •Worker – command line style  gearman -w -f wc -- wc –l •Client – command line style  gearman -f wc < /etc/passwd •Check it! Simple Bash Example
15. 15 PHP Style
16. 16 •So, you know… we all like to talk about ourselves…  Yes, I wrote a layer on top of Zend Framework called Zend_Gearman; wow unique.  https://github.com/mwillbanks/Zend_Gearman PHP – Zend Framework
17. The Details Persistence Workers Monitoring
18. 18 •Gearman by default is an in-memory queue  Leaving this as the default is ideal; however, does not work in all environments. •Persistent Queues  Libdrizzle  Libsqlite3  Libmemcached  Postgres  TokyoCabinet  MySQL  Redis Persistence
19. 19 •Persistent queues require specific configuration during the compilation of gearman. •Additionally, arguments to the gearman daemon need to be passed to talk to the specific persistence layer. •Each persistence layer is actually built as a plugin to gearmand  http://bazaar.launchpad.net/~tangent- org/gearmand/trunk/files/head:/libgearman- server/plugins/queue/ Getting Up and Running with Persistence
20. 20 Configuration Options
21. 21 •Clients send work to the gearmand server  This is called the workload; it can be anything that can become a string.  Utilize an open format; it will make life easier if you chose to use a different language for processing • XML, JSON, etc. • Yes, you can serialize objects if you wanted to… not recommended although. Clients
22. 22 •Workers are the dudes in the factory doing all the work •Generally they will run as a daemon in the background •Workers register a function that they perform  They should ONLY be doing a single task.  This makes them far easier to manage. •The worker does the work and “can” return results  If you are doing the work asynchronously you generally do not return the result.  Synchronous work you will return the result. Workers
23. 23 •Utilizing the Database  If you keep a database connection • Must have the ability to reconnect to the database. • Watch for connection timeouts •Handling Memory Leaks  Watch the amount of memory and detect leaks then kill the worker. •Request Languages  PHP for instance, sometimes slows down after hundreds of executions, kill it off if you know this will happen. Workers – special notes
24. 24 •Workers sometimes have issues and die, or you need to boot them back up after a restart  Utilizing a service to watch your workers and ensure they are always running is a GOOD thing. •Supervisord  Can watch processes, restart them if they die or get killed  Can manage multiple processes of the same program  Can start and stop your workers. •When running workers, BE SURE to handle KILL signals such as SIGKILL. Keeping the Daemon Running
25. 25 Supervisord Example
26. 26 •Until recently you were writing something against the gearman socket interface…  telnet on port 4730  Write “STATUS” • Gives you the registered functions, number of workers and items in the queue. •Gearman Monitor – PHP Project  NOTE: I’ve never actually attempted this; BUT it is referenced on gearman.org so it must be doing something!  https://github.com/yugene/Gearman-Monitor Monitoring
27. Use Cases Email Photos Log Analysis / Aggregation
28. 28 •If you resize images on your web server:  Web servers should serve, not process images.  Images require a lot of memory AND processing power • They are best to be processed on their own! •Processing in the Background  Generally will require a change to your workflow and checking the status with XHR to see if the job has been completed. • This allows you to process them as you have resources available. • Have enough workers to process them “quickly enough” Images
29. 29 Image Processing Example
30. 30 •Sending email and/or generating templates and processing variables can take up time, time that is better spent getting the user to the next page. •The feedback on the mail doesn’t really make a difference so it is great to send it to the background. Email
31. 31 Email Example
32. 32 •Get all of your logs to a single place •Process the logs to produce analytical data •Impression / Click Tracking •Why run a cron over your logs nightly?  Real-time data is where it is at! Log Analysis / Aggregation
33. 33 Log Analysis / Aggregation
34. Questions? These slides will be posted to SlideShare & SpeakerDeck. Slideshare: http://www.slideshare.net/mwillbanks SpeakerDeck: http://speakerdeck.com/u/mwillbanks Twitter: mwillbanks G+: Mike Willbanks IRC (freenode): mwillbanks Blog: http://blog.digitalstruct.com GitHub: https://github.com/mwillbanks