The document provides an introduction to the LMAX Disruptor, a data structure for high performance inter-thread messaging. It describes the Disruptor as allowing very fast message passing without contention by using a lock-free data structure called a ring buffer. The workshop covers the basic components of the Disruptor including the publisher, event handlers, and batch processing. It includes exercises to demonstrate wiring up a simple Disruptor configuration, adding parallel event handlers, and managing dependencies between handlers. Real-world uses like high throughput financial applications are also discussed.

1. An Introduction to the
LMAX Disruptor
Trisha Gee, Developer at LMAX Exchange
@trisha_gee
mechanitis.blogspot.com
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2. Laptop Setup... Go!
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3. The Disruptor?
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4. The Workshop
• Introduction to the Disruptor
• Simplest Case
• Performance Results
• Going Parallel
• The Real World
• Questions
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5. What is The Disruptor?
• Very fast message passing
• Data structure and work flow without
contention
• Allows you to go truly parallel
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6. So...?
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7. The Magic RingBuffer
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8. The Magic RingBuffer
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9. The Magic RingBuffer
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10. The Magic RingBuffer
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11. The Magic RingBuffer
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12. The Magic RingBuffer
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13. The Events are Buckets
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14. I’ve got a RingBuffer!
• Erm.... how do I poke things into it?
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15. The Publisher
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22. ...so now I want to read
• The Disruptor provides nice batching
behaviour for free
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23. BatchEventProcessor
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38. The Problem
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39. Tower Defence?
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45. Exercise One
One publisher, one event handler
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46. Our Problem
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47. Simplest Disruptor
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48. TODO
• Print status of the enemy when the tower
sees it
• Print status of enemy after the tower
shoots it
• Shoot all enemies
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49. Task Breakdown
• Wire up the EventTranslator &
EventHandler, using the Disruptor class
• Implement shootAt
• Implement respawn & isDead
• Get unit tests to pass
• (check out mechanitis.examples.disruptor)
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50. Exercise One Goals
1. Understand the roles of Translators and
Event Handlers
2. Understand how to wire up a simple
Disruptor configuration
3. Understand how to get events flowing
through the Disruptor
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51. Performance vs a
Queue
Mac Air, 1.7GHz Core i5:
run 0: BlockingQueue=3,390,060 Disruptor=69,108,500 ops/sec
run 1: BlockingQueue=5,229,851 Disruptor=71,123,755 ops/sec
run 2: BlockingQueue=4,303,481 Disruptor=65,530,799 ops/sec
Disruptor - Time Taken: 3,242 millis
Disruptor - Time Taken: 3,319 millis
Disruptor - Time Taken: 4,045 millis
Queue - Time Taken: 30,022 millis
Queue - Time Taken: 31,823 millis
Queue - Time Taken: 29,280 millis
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52. Exercise Two
One publisher, two parallel event handlers
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53. Let’s log all the enemies
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54. Parallel Processors
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55. • Make each enemy unique
• Write the details of each enemy generated
into a text file
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56. Task Breakdown
• Add randomness to enemy (e.g. give them a
speed to travel at)
• Wire in the EnemyLogger
• Implement describeTo in enemy
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57. Exercise Two Goals
1. Understand that EventHandlers can
process in parallel
2. Understand how to wire up EventHandlers
in parallel
3. Understand the caveats to going parallel -
single writer principal
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58. Exercise Three
Diamond Dependencies
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59. Recording the Results
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60. Sequence Barriers
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61. Managing Dependencies
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62. • Don’t use the Disruptor Wizard for
configuration
• Record results of the game to a different
text file
• Optional: add variability to Turret
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63. Task Breakdown
• Remove use of Disruptor.java and wire up
manually (mechanitis.examples.disruptor)
• Wire in ResultHandler
• Add missing things from Enemy class
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64. Exercise Three Goals
1. Understand sequence barriers
2. Understand different dependency
configurations
3. Understand wiring up without the wizard
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65. Exercise Four
Playtime!!
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66. Slow Consumers?
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67. The Real World
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71. Ticket Purchasing
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79. Other Uses
• Queue replacement
• Single-threading your code
• Filtering
• Coalescing
• Dependency graphs
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80. Questions
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