nim-taskpools/README.md

Taskpools

API

The API spec follows https://github.com/nim-lang/RFCs/issues/347#task-parallelism-api

Overview

This implements a lightweight, energy-efficient, easily auditable multithreaded taskpools.

This taskpools will be used in a highly security-sensitive blockchain application targeted at resource-restricted devices hence desirable properties are:

• Ease of auditing and maintenance.
  • Formally verified synchronization primitives are highly-sought after.
  • Otherwise primitives are implemented from papers or ported from proven codebases that can serve as reference for auditors.
• Resource-efficient. Threads spindown to save power, low memory use.
• Decent performance and scalability. The workload to parallelize are cryptography-related and require at least 1ms runtime per thread. This means that only a simple scheduler is required.

Non-goals:

• Supporting task priorities
• Being distributed
• Supporting GC-ed memory on Nim default GC (sequences and strings)
• Have async-awaitable tasks

In particular compared to Weave, here are the tradeoffs:

• Taskpools only provide spawn/sync (task parallelism).
  There is no parallel for (data parallelism)
  or precise in/out dependencies (dataflow parallelism).
• Weave can handle trillions of small tasks that require only 10µs per task. (Load Balancing overhead)
• Weave maintains an adaptive memory pool to reduce memory allocation overhead, Taskpools allocations are as-needed. (Scheduler overhead)