Crate fast_counter

Fast-counter is a shareded concurrent atomic counter

The library works by sharding the atomic numbers between multiple values, each thread will attempt to read from a different cell. This helps with cache-thrashing and contention. This benefit is seen when there is a greater number of threads competing over a single cell, on my machine with 16 cores attempting to update the value it can be nearly 60x faster. The price you pay for this is higher memory usage as we have multiple Atomic numbers which are cache-padded so can be significantly higher.

Usage

Usage of the library is simple, create a new ConcurrentCounter with then number of shards you wish to have, internally the library will use the next power of two as the number of cells for a faster modulus.

use fast_counter::ConcurrentCounter;

let counter = ConcurrentCounter::new(10);

counter.add(1);

let sum = counter.sum();

assert_eq!(sum, 1);

Performance considerations

The library will perform best when the threads are accessing their own cell consistently. This can helped by making sure more than enough cells are allocated for the number of threads which are going to be writing to the cell.

Due to the sharding behaviour the time to call the sum() method does slow down with the increase in shards, if this becomes a bottleneck it may be worth investigating running with a lower shard counter

Re-exports

pub use counter::*;

Modules

counter