Know Your Execution Context

Lorenzo Barasti

15MWE December 2016

Table de Matières

• What's an execution context?
• CPU bound and IO bound operations
• Which execution context should I use?
• Conclusions

def executionContext

An Execution Context is an abstraction that lets us schedule and run tasks in a predictable way

(Some) Types of

Execution Context

• FixedThreadPool

• SingleThreadExecutor 

• WorkStealingPool

• ExecutionContext.global 

FixedThreadPool

 reuses a fixed number of threads operating off a shared unbounded queue

WorkStealingPool - fork/join

• Dynamic number of threads up to a custom level
• Multi-Queue
• No guarantees on the order in which tasks will be executed

CachedThreadPool

creates new threads as needed, but will reuse previously constructed threads when they are available

Conclusions

• Look for the right EC for your use case
• Avoid using the same execution context for different types of operations
• Mind that in this context implementation matters
• Tell your friends!

References

• Docs for Java's Executor
• Introducing thread pools
• Executor's factory methods
• Scala docs for the Global Execution Context
• The Fork/Join framework and a general definition of work stealing