Scala & Concurrency
Nikhil Anurag
Scala & Concurrency
Who am I?
- My name is Nikhil
- Working at Zalando SE
- Functional Scala - Cats, fs2, http4s
- Wrote a book, Distributed Computing with Go
Scala & Concurrency
Agenda
- Concurrency & Parallelism
- JVM
- Scala
- Project Loom
Concurrency vs. Parallelism
Sequential Execution
You
Call 1
Email
1/2
Prep
Food
Call 2
Email
2/2
Eat
Food
Split Sequential Execution
You & Roomie
Call 1
Email
1/2
Prep
Food
Call 2
Email
2/2
Eat
Food
Watch
TV
Concurrency
Call 1
Email
1/2
Prep
Food
Call 2
Email
2/2
Eat
Food
Parallelism
Call 1
Email
1/2
Prep
Food
Call 2
Email
2/2
Eat
Food
Watch
TV
Concurrency on JVM
Levels of Abstraction
# Cores
OS Threads
Available
Resources
Ease of Creation
OS Threads
Levels of Abstraction
# Cores
OS Threads
JVM Threads
Available
Resources
Ease of Creation
Levels of Abstraction
# Cores
OS Threads
JVM Threads
Thread Pool
Available
Resources
Ease of Creation
Thread Pools
Thread Pools
Thread
Task
Thread Pools
Thread Pool
Free: 4
Busy: 0
Thread Pools
Task Queue: 4
Thread Pool
Free: 4
Busy: 0
Thread Pools
Task Queue: 3
Thread Pool
Free: 3
Busy: 1
Thread Pools
Task Queue: 2
Thread Pool
Free: 2
Busy: 2
Thread Pools
Task Queue: 1
Thread Pool
Free: 1
Busy: 3
Thread Pools
Task Queue: 0
Thread Pool
Free: 0
Busy: 4
Thread Pools
Task Queue: 0
Thread Pool
Free: 0
Busy: 4
Thread Pools
Task Queue: 1
Thread Pool
Free: 0
Busy: 4
Thread Pools
Task Queue: 1 (Waiting)
Thread Pool
Free: 0
Busy: 4
Thread Pools
Task Queue: 2 (Waiting)
Thread Pool
Free: 0
Busy: 4
Levels of Abstraction
# Cores
OS Threads
JVM Threads
Thread Pool
Available
Resources
Ease of Creation
Concurrency in Scala
Levels of Abstraction
# Cores
OS Threads
JVM Threads
Thread Pool
Fibers
Tasks
Available
Resources
Ease of Creation
Cats Effect IO
&
Monix Tasks
Sequential Execution
Call 1
Email
1/2
Prep
Food
Call 2
Email
2/2
Eat
Food
Cats Effect IO
Cats Effect IO
Call 1
Email
1/2
Prep
Food
Call 2
Email
2/2
Eat
Food
Cats Effect IO
Call 1
Email
1/2
Prep
Food
Call 2
Email
2/2
Eat
Food
Cats IO: Sequential execution on a single thread
Concurrency
Call 1
Email
1/2
Prep
Food
Call 2
Email
2/2
Eat
Food
Monix Tasks
Monix Tasks
Call 1
Email
1/2
Prep
Food
Call 2
Email
2/2
Eat
Food
Monix Tasks
Call 1
Email
1/2
Prep
Food
Call 2
Email
2/2
Eat
Food
Monix Task: Execution with scheduled breaks
Project Loom
Levels of Abstraction
# Cores
OS Threads
JVM Threads
Available
Resources
Ease of Creation
Levels of Abstraction
(Project Loom)
# Cores
OS Threads
Available
Resources
Ease of Creation
# Cores
OS Threads
Available
Resources
Ease of Creation
JVM Threads
Levels of Abstraction
(Project Loom)
# Cores
OS Threads
Available
Resources
Ease of Creation
JVM Threads
Thread Pool
Fibers
Levels of Abstraction
(Project Loom)
Fibers?
Call 1
Email
1/2
Prep
Food
Call 2
Email
2/2
Eat
Food
Questions?
Scala & Concurrency
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