You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
38 lines
2.0 KiB
Markdown
38 lines
2.0 KiB
Markdown
8 years ago
|
# A Parallel Mandelbrot Set Plotter
|
||
|
|
||
|
This program plots the Mandelbrot set and writes it out as a PNG file. It uses Rust's concurrency primitives to distribute the work across eight threads.
|
||
|
|
||
|
Different commits show different implementation strategies:
|
||
|
|
||
|
* [Branch `single-threaded`](https://github.com/jorendorff/rust-mandelbrot/blob/single-threaded/src/main.rs)
|
||
|
is the base version of the program. It does all the work on the main
|
||
|
thread.
|
||
|
|
||
|
* [Branch `bands`](https://github.com/jorendorff/rust-mandelbrot/commit/bands)
|
||
|
splits the plotting area up into eight bands, and assigns one thread
|
||
|
to each. This often makes poor use of the threads, because some
|
||
|
bands take significantly longer than others to complete: once a fast
|
||
|
thread completes its band, its CPU goes idle while its less
|
||
|
fortunate brethren are still hard at work.
|
||
|
|
||
|
* [Branch `task-queue`](https://github.com/jorendorff/rust-mandelbrot/commit/task-queue)
|
||
|
gets an almost perfect linear speedup from its threads. It splits
|
||
|
the plotting area up into many more bands, and then has threads draw
|
||
|
bands from a common pool until the pool is empty. When a thread
|
||
|
finishes one band, it goes back for more work. Since the bands still
|
||
|
take different amounts of time to render, the problem cited above
|
||
|
still occurs, but on a much smaller scale.
|
||
|
|
||
|
* [Branch `lockfree`](https://github.com/jorendorff/rust-mandelbrot/commit/lockfree)
|
||
|
uses Rust's atomic types to implement a lock-free iterator type, and
|
||
|
uses that to dole out bands from the pool instead of a
|
||
|
mutex-protected count. On Linux, this is no faster than the
|
||
|
mutex-based version, which isn't too surprising: on Linux, locking
|
||
|
and unlocking an uncontended mutex *is* simply a pair of atomic
|
||
|
operations.
|
||
|
|
||
|
* [Branch `rayon`](https://github.com/jorendorff/rust-mandelbrot/commit/rayon)
|
||
|
uses the Rayon library instead of Crossbeam. Rayon provides a
|
||
|
*parallel iterator* API that makes our code much simpler. It looks
|
||
|
a lot like Rust code that uses plain old iterators.
|