Benchmark: push/shift vs rotating pointer

Script Preparation code:

var size = 20;
var arr = [...Array(size)].map((_, idx) => idx);
var pointer = 0;

Tests:

push -> shift
arr.push(123) arr.shift()
rotating pointer
arr[pointer++] = 123; if (pointer >= size) pointer = 0;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
push -> shift
rotating pointer

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of MeasureThat.net and explore what's being tested in this benchmark.

**Benchmark Definition**

The benchmark is designed to compare two approaches for modifying an array: using `arr.push()` followed by `arr.shift()`, and using a rotating pointer approach. The goal is to determine which method is faster.

**Options Compared**

There are two main options being compared:

1. **`push -> shift`**: This approach involves adding an element to the end of the array using `arr.push(123)` and then removing the first element using `arr.shift()`.
2. **Rotating Pointer**: This approach uses a pointer variable (`pointer`) to keep track of the current position in the array. When a new element is added, the pointer increments and wraps around to 0 when it reaches the end of the array.

**Pros and Cons**

* **`push -> shift`**:
	+ Pros: Simple and intuitive approach.
	+ Cons: May involve more overhead due to the need to remove elements from the beginning of the array.
* **Rotating Pointer**:
	+ Pros: Can be faster since only a single element needs to be removed from the array, rather than shifting all elements after it.
	+ Cons: Requires an additional variable (`pointer`) and can be more complex to implement.

**Library**

The benchmark uses JavaScript's built-in `Array` data structure. No external libraries are required.

**Special JS Feature/Syntax**

None mentioned in this benchmark. However, the rotating pointer approach does utilize a common optimization technique in JavaScript: using an index variable to track the current position in an array.

**Other Considerations**

* **Cache Locality**: The `push -> shift` approach may benefit from cache locality since elements are added and removed from adjacent positions in the array.
* **Array Resizing**: When adding or removing elements, arrays may need to be resized. This can impact performance. The rotating pointer approach avoids this overhead.

**Alternatives**

If you're looking for alternative approaches or optimizations, consider:

1. **Using a circular buffer**: Implementing a circular buffer using a separate array and index variable could potentially outperform the rotating pointer approach.
2. **Compiling to machine code**: Utilizing JavaScript engines like V8 (used in Chrome) that can compile JavaScript to native machine code might lead to performance improvements.

Keep in mind that optimizations and benchmarking results may vary depending on the specific use case, JavaScript engine, and system configurations.

Related benchmarks:

push/shift vs rotating pointer (version: 1)

I'm confused why replacing the entries in the array takes longer than adding to the end and removing the first entry.

Comparing performance of: push -> shift vs rotating pointer

Created: 2 years ago by: Registered User

Jump to the latest result

push -> shift

rotating pointer

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):