1. New trends in parallel computing
Go, Julia, Go!
New trends in parallel computing

2. Covered topics
Modern parallel languages for shared and distributed memory computing
golang
Julia

3. Motivation
The search for elegant and high—performance parallel language is neverending
C-like leads in performance
Python leads in comprehension and ease of use
Matlab is the favourite of engineers
Some people like it functional: Erlang
So what has been going on recently?

4. Go Also known as ‘golang’ From big influencers in the field
compiled,
statically typed,
object oriented,
garbage-collected
built-in concurrency primitives and CSP-like parallelism
From big influencers in the field
(Ken) Thompson, (rob) Pike, Cox, Griemser
Backed by a big company
Guess which one

5. Go Communicating sequential processes (Hoare)
“Do not communicate by sharing memory; instead, share memory by communicating.”
Pattern of interaction in concurrent systems
Formally: process algebra, process calculus
Implements IPC via message passing (even in shared memory) through shared channels
Helpful for development of verified concurrent systems
Handy for handling critical sections, pooled operations

6. Go Key properties Statically typed and well-scalable (like C++, Java)
Light (like python and ruby)
Far away from the unnecessary complexity of C++-like langs
Large built-in library
Fast compiler (statically linked binaries)
Testing framework

7. Go Goroutines A goroutine is a lightweight thread of execution.
Implemented as a function or anonymous function.
Semi-cooperatively scheduled

8. Go Channels Channels are the pipes that connect concurrent goroutines
You can send values into channels from one goroutine and receive those values into another goroutine
Typed by values they convey
Send a value into a channel using the channel <- syntax. Here we send "ping" to the messages channel we made above, from a new goroutine.

9. Go
Channels can be
used for synchronization

10. Go Channels can be used for synchronization
directed (good for type safety)

11. Go Channels can be used for synchronization
directed (good for type safety)
part of a select statement

12. Go Channels can be used for synchronization
directed (good for type safety)
part of a select statement
with a timeout

13. Go Channels can be used for synchronization
directed (good for type safety)
part of a select statement
with a timeout
or with a default value (non-blocking)

14. Julia
High-level, high-performance dynamic language for technical computing
Distributed parallel execution, plentiful libraries
LLVM-based JIT compiler
‘One-sided’ implementation of message passing
programmer needs to explicitly manage only one process in a two-process operation
Communication resembles higher-level operations like calls to user functions

15. Julia two key primitives: remote references and remote calls
an object that can be used from any process to refer to an object stored on a particular process
two flavors - Future and RemoteChannel
Remote call
request by one process to call a certain function on certain arguments on another (possibly the same) process
returns a Future to its result

16. Julia Other useful concepts Synchronization Scheduling
Distributed garbage collection
Channels
Shared arrays