clj-stm-poc

Proof of concept for STM usage (atoms, agents, STM) in management of finite stateful resources, such as limited connection resources for DB access.

Requirements

Following must be installed:

• Java
• Leiningen

Usage

Standalone Server (manual testing)

1. $ lein ring server-headless
2. Access Swagger via http://localhost:3000/index.html#/api

Automated Testing of concurrent connections

1. $ lein test

Thoughts

STM investigation results

Due to the try/retry-on-change nature of STM and Agents, proper usage requires pure (side-effect free) functions. As such, concurrency mechanics specific to CLJ fit poorly when designing an I/O based concurrency operators. (To further emphasize this necessity, io! is provided as a safeguard for libraries against any injected operations causing side effects.)

Several other options exist for writing concurrency safe code.

• Standard Java concurrency libraries are still available and provided within the clj locking libraries

• Atoms/Refs may still be used to create transaction states, but the resulting code will resemble typical imperative code blocks rather than functional ones. (This is final approach used within this project.)

• Erlang-style Actor systems may be used through several available packages, the most notable of which is the Akka wrapper okku

License

Copyright © 2017