README
¶
Collatz
This directory contains a Service Weaver application that explores the
Collatz conjecture. Given a positive integer x, the Collatz process
is the process of repeatedly executing the following operation:
- If
xis even, setxtox/2. - If
xis odd, setxto3x+1.
For example, if we execute the Collatz process on x = 10, then we get the
sequence of numbers 10, 5, 16, 8, 4, 2, 1. This sequence of numbers is called
the hailstone sequence of 10. The Collatz conjecture states that the hailstone
sequence of every positive number reaches 1. Nobody knows if the Collatz
conjecture is true; it is one of the most famous unsolved problems in
mathematics.
This Service Weaver application implements a service that executes the Collatz process. You can send the service a positive number, and the server replies with that number's hailstone sequence.
Components
This Service Weaver application has three components: main, Odd and Even. Given a
positive number x, main repeatedly calls Odd (if x is odd) or Even (if
x is even) to receive the next number in the hailstone sequence.
%%{init: {"flowchart": {"defaultRenderer": "elk"}} }%%
graph TD
%% Nodes.
github.com/ServiceWeaver/weaver/Main(weaver.Main)
github.com/ServiceWeaver/weaver/examples/collatz/Even(collatz.Even)
github.com/ServiceWeaver/weaver/examples/collatz/Odd(collatz.Odd)
%% Edges.
github.com/ServiceWeaver/weaver/Main --> github.com/ServiceWeaver/weaver/examples/collatz/Even
github.com/ServiceWeaver/weaver/Main --> github.com/ServiceWeaver/weaver/examples/collatz/Odd
This application highlights the benefits of colocation. The performance of the
application improves significantly when main, Odd, and Even are colocated
in the same OS process.
Running Locally
To run this app locally, run go run .. In a separate terminal, curl the
service (which defaults to localhost:9000):
$ go run . # In one terminal.
$ curl localhost:9000?x=27 # In a different terminal.
To run the app across multiple processes, use weaver multi deploy. The
weaver.toml config file runs every component in a separate process, and the
colocated.toml config file colocates all three components.
$ weaver multi deploy weaver.toml # not colocated
$ weaver multi deploy colocated.toml # colocated
Running on GKE
To run the app on GKE, use weaver gke deploy:
$ weaver gke deploy weaver.toml
Documentation
¶
Overview ¶
Package main implements a service that explores the Collatz conjecture.
Given a positive integer x, the Collatz process is the process of repeatedly executing the following operation:
- If x is even, set x to x/2.
- If x is odd, set x to 3x+1.
For example, if we execute the Collatz process on x = 10, then we get the sequence of numbers 10, 5, 16, 8, 4, 2, 1. This sequence of numbers is called the hailstone sequence of 10. The Collatz conjecture states that the hailstone sequence of every positive number reaches 1. Nobody knows if the Collatz conjecture is true; it is one of the most famous unsolved problems in mathematics.
Package main implements a service that executes the Collatz process. You can send the service a positive number, and the server replies with that number's hailstone sequence.
The service is implemented as an HTTP server that uses two Service Weaver components: Odd and Even. Odd has a method Do that takes in an odd number x and returns 3x+1. Even has a method Do that takes in an even number x and return x/2. When the HTTP server receives a number x, it repeatedly sends x to either Odd or Even---depending on whether x is odd or even---until x equals 1. It then sends back the hailstone sequence.
This Service Weaver application is interesting because it demonstrates the benefits of colocation. Colocating the main component with the Odd and Even components improves performance considerably.
Source Files