Benchmark: new set vs reusing set

Tests:

new set
const create = () => { const set = new Set() for (let i = 0; i < 1000; ++i) set.add(i) return set } for (let i = 0; i < 100; ++i) { const result = create() }
reuse set
const set = new Set() const create = () => { set.clear() for (let i = 0; i < 1000; ++i) set.add(i) return [...set] } for (let i = 0; i < 100; ++i) { const result = create() }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new set
reuse set

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 28 days ago):

LLMs can make mistakes. Check important info.

This benchmark compares two different approaches to working with the `Set` data structure in JavaScript: creating a new `Set` instance each time versus reusing the same `Set` instance by clearing it before adding new elements. Below, I will break down the options being tested, their pros and cons, as well as other relevant considerations.

### Benchmark Comparison

1. **Creating a New Set** (`new set`):
   - **Code Explanation**:
     ```javascript
     const create = () => {
         const set = new Set();
         for (let i = 0; i < 1000; ++i) {
             set.add(i);
         }
         return set;
     };

for (let i = 0; i < 100; ++i) {
         const result = create();
     }
     ```
   - **Description**:
     In this test case, a new instance of `Set` is created every time the `create` function is invoked. The function adds 1000 items (from 0 to 999) to this new `Set`.

- **Pros**:
     - **Isolation**: Each test run is independent, starting with a clean slate. This avoids any potential side effects from previous operations on the same set.
     - **Simplicity**: This method is straightforward and adheres to a functional programming style, where each function call has no side effects on the global state.

- **Cons**:
     - **Memory Overhead**: Each new `Set` instance creates overhead due to allocation and eventual garbage collection.
     - **Performance**: Repeated creation can be slower in scenarios where the overhead of instantiating objects is non-negligible.

2. **Reusing a Set** (`reuse set`):
   - **Code Explanation**:
     ```javascript
     const set = new Set();
     const create = () => {
         set.clear();
         for (let i = 0; i < 1000; ++i) {
             set.add(i);
         }
         return [...set];
     };

for (let i = 0; i < 100; ++i) {
         const result = create();
     }
     ```
   - **Description**:
     In this test, a single `Set` instance is created outside the `create` function. Each time `create` is called, the existing `Set` is cleared before adding new items, thus avoiding the overhead of new instance creation.

- **Pros**:
     - **Performance**: Reduced overhead from memory allocations can lead to better performance, especially in scenarios where the function is called many times.
     - **Less Garbage Collection**: By reusing the same instance, there's less pressure on the garbage collector, which can enhance performance in long-running scripts.

- **Cons**:
     - **Statefulness**: If the `create` function does not correctly clear the `Set`, it may lead to unintended behavior across invocations. This could potentially introduce bugs.
     - **Complexity**: Managing stateful objects can introduce complexities that should be carefully handled.

### Benchmark Results Summary

The benchmark results show the following executions per second for each approach:

- **New Set**: 273.97 executions per second
- **Reuse Set**: 227.90 executions per second

In this case, creating a new `Set` proved to be more performant in this particular browser and operating environment, which may seem counterintuitive given the potential overhead of allocation. However, performance can vary across different browsers, JavaScript engines, and environments, and may also be influenced by optimizations performed by the engine in question.

### Considerations and Alternatives

- **Memory Management**: In JavaScript, memory management and garbage collection can significantly impact performance. Developers should be mindful of how their code may affect memory usage and strive for efficient practices.

- **Further Alternatives**: Depending on application requirements, developers might consider:
  - **Array**: Using an array and leveraging array methods (`filter`, `includes`, etc.) for operations might be a viable alternative, particularly for small sets of known data.
  - **Typed Arrays**: These can offer performance improvements for numeric data but may lack the rich feature set of native collections like `Set`.
  - **Immutable Data Structures**: Libraries like Immutable.js may provide more predictable and efficient performance patterns for specific use cases, especially in functional programming paradigms.
  
In summary, the choice between creating a new `Set` and reusing an existing one depends largely on the unique requirements of the application, performance needs, and the developer's familiarity with managing state in JavaScript.

Latest run results:

Run details: (Test run date: 28 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
new set	814.7 Ops/sec
reuse set	357.8 Ops/sec

Related benchmarks:

new set vs reusing set (version: 0)

Comparing performance of: new set vs reuse set

Created: 29 days ago by: Guest

Jump to the latest result

new set

reuse set

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 28 days ago):