@diego_pachecoSoftware Architect | Agile Coach

STM

Moore's law (Number os Transistors double ~2 years)

AMD Athlon 64 FX-53 CPU 2.4 GHz - Single CORE - 2005

Single Thread App: It’s ALL OVER !!!

More Than one CORE: Dual, Quad, etc..

Concurrent Threads == Challenges

Order of operations is not fixed…

Difficult to repeat failures…

WE often don’t think this way…

Testing effort is bigger…

JOB

P1

P2

P3

P5P4

JOBDONE

Multithreaded: 2 General Categories

JOB Group

JOB GroupDONE

J1J2

J3

J4 J5

Current Models

LocksActors

STM

Current Models - LOCKS

Locks

Shared-Memory

Surreal

OO

Actors

Current Models - Actors

NO Shared Data

Async Messages Lightweight Threads

Current Models - STM

STM

ACID

STM Implementations Guarantee NO:

Livelock

Race Conditions

Dead Locks

STM Issues:

Retry Waste: Lots of transactions retry

Overhead: Transaction Bookkeeping

Lack of Tools: Identify, learn, tunning, etc...

Clojure/Haskell: All Immutable

Everything is immutable!Change: AlwaysInside a Transaction.

Clojure: Persistent Data Structures

Clojure STM Implementation

Multi-Version Concurrency Control (MVCC) + Snapshot isolation

Databases (Mysql, Postgress & Oracle), Subversion, EhCache, JBoss Cache Clojure and several other solutions…

@diego_pachecoSoftware Architect | Agile Coach

STM

Thank You!