Benchmark: Caching Uint8Array length property vs getting it each time in the loop

Script Preparation code:

var arr = new Uint8Array(1000);
arr.fill(0xff)

Tests:

Cache length
var arrLen = arr.length; var sum = 0; for (var i = 0; i < arrLen; i++){ sum = arr[i]; }
Do not cache
var sum = 0; for (var i = 0; i < arr.length; i++){ sum = arr[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Cache length
Do not cache

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 4 days ago):

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided benchmark, "Caching Uint8Array length property vs getting it each time in the loop", aims to measure the performance difference between two approaches when iterating over a `Uint8Array` object.

**Benchmark Definition JSON Explanation**

The benchmark definition is represented by the following JSON:
```json
{
  "Name": "Caching Uint8Array length property vs getting it each time in the loop",
  "Description": "...",
  "Script Preparation Code": "var arr = new Uint8Array(1000);\r\narr.fill(0xff)",
  "Html Preparation Code": null
}
```
Here's what each part represents:

* `Name` and `Description`: The name of the benchmark and a brief description.
* `Script Preparation Code`: A JavaScript code snippet that prepares the test environment. In this case, it creates a new `Uint8Array` object with 1000 elements filled with the value 0xff.
* `Html Preparation Code`: An empty string, indicating that no HTML-related preparation is required.

**Individual Test Cases**

The benchmark consists of two individual test cases:

1. **Cache length**: This test case caches the length of the `Uint8Array` object in a variable (`var arrLen = arr.length;`) and then uses this cached value to iterate over the array.
2. **Do not cache**: This test case does not cache the length of the `Uint8Array` object and instead retrieves it within the loop (`arr.length`).

**Comparison of Options**

The two test cases differ in how they access the length of the `Uint8Array` object:

1. **Caching the length**: By caching the length, the test case avoids repeated lookups within the loop. This approach can reduce memory access and improve performance.
2. **Not caching the length**: In this approach, the length is retrieved every iteration, which may lead to slower performance due to increased memory access.

**Pros and Cons**

* **Caching the length**:
	+ Pros: Reduced memory access, potentially improved performance.
	+ Cons: Additional memory allocation for the cached value.
* **Not caching the length**:
	+ Pros: No additional memory allocation required.
	+ Cons: Increased memory access within the loop, potential performance degradation.

**Other Considerations**

* The use of `Uint8Array` and its properties is specific to JavaScript's typed arrays. Other programming languages or libraries may use different data structures or approaches.
* The benchmark's focus on caching vs not caching the length might be influenced by the underlying hardware and browser optimizations.

**Libraries and Special JS Features**

There are no libraries explicitly mentioned in the provided benchmark definition or test cases. However, JavaScript's typed arrays (`Uint8Array`, `Int8Array`, etc.) provide a convenient way to work with fixed-size binary data structures.

No special JavaScript features are used in these test cases.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.106 Safari/537.36

Browser/OS: Chrome 91 on Windows

View result in a separate tab

Test name	Executions per second
Cache length	16420.6 Ops/sec
Do not cache	8107.3 Ops/sec

Related benchmarks:

Caching Uint8Array length property vs getting it each time in the loop (version: 0)

save length of the u8arr in the variable vs get it the loop

Comparing performance of: Cache length vs Do not cache

Created: 3 years ago by: Guest

Jump to the latest result

Cache length

Do not cache

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 4 days ago):