Concurrency

Current operational environments are typically distributed:

• composed by multiple systems.

• distributed information/resources.

• distributed clock.

Algorithms are frequently developed as actions that use those resources.

• Commonly mapped to sequential actions.

However... interactions/side effects between systems can make some “naive“ assumptions false.

• Information is available on demand.

• Writing to an object makes it available to other components.

• Time flows in a single direction.

Even if algorithms account for the distributed execution, side effects may be present.

• Variable access latency.

• Variable execution paths.

• Variable object metadata.

• Variable locks.

Side effects can affect execution or disclose information between domains.

• How an algorithm is implemented, what it is doing.

• Keys used.

• Users active.