Benchmark: Using a global context variable versus getting the context on each draw call

HTML Preparation code:

<canvas id="canvas" width="800" height="300"></canvas>

Script Preparation code:

$canvas = document.getElementById('canvas');
$context = $canvas.getContext('2d');
$context.clearRect(0, 0, 800, 300);

$iterations = 500;

Tests:

Using a global context variable
for (let i=0; i<$iterations; ++i) { $context.fillStyle = 'rgba(100,150,200,0.9)'; $context.fillRect(0, 0, 1, 1); }
Invoking getContext() before every fillRect()
for (let i=0; i<$iterations; ++i) { const context = $canvas.getContext('2d'); context.fillStyle = 'rgba(100,150,200,0.9)'; context.fillRect(0, 0, 1, 1); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using a global context variable
Invoking getContext() before every fillRect()

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.116 Safari/537.36 Edg/83.0.478.61

Browser/OS: Chrome 83 on Windows

View result in a separate tab

Test name	Executions per second
Using a global context variable	1796.8 Ops/sec
Invoking getContext() before every fillRect()	1017.4 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**Benchmark Purpose**

The benchmark tests two different approaches to rendering a small rectangle on a canvas element:

1. Using a global context variable
2. Invoking `getContext()` before every fillRect() call

The goal is to compare the performance of these two approaches and determine which one is faster.

**Options Compared**

The two options being compared are:

* Option 1: Using a global context variable, which sets up the context once at the beginning of the benchmark and uses it for all subsequent draw calls.
* Option 2: Invoking `getContext()` before every fillRect() call, which creates a new context instance on each iteration of the loop.

**Pros and Cons**

* **Option 1 (Global Context Variable)**
	+ Pros:
		- Reduces overhead by creating the context only once
		- Can be faster since the context is reused multiple times
	+ Cons:
		- May lead to memory leaks if not properly cleaned up
		- Can cause issues if the canvas element is dynamically added or removed from the DOM
* **Option 2 (Invoking getContext() before every fillRect())**
	+ Pros:
		- Ensures a new context instance is created for each draw call, which can prevent memory leaks
		- Can be beneficial in cases where multiple canvases need to be rendered with different contexts
	+ Cons:
		- Increases overhead due to the repeated creation of context instances
		- Can result in slower performance since each context iteration incurs a new allocation

**Library and Special JS Feature**

The benchmark uses the `canvas` HTML element, which is a standard part of the web platform. There are no external libraries required.

There are no special JavaScript features or syntax used in this benchmark.

**Other Considerations**

* The benchmark assumes that the canvas element will be rendered on a device that supports multiple execution threads (e.g., modern desktop and mobile devices).
* The benchmark does not account for any potential issues related to the canvas element's size, resolution, or aspect ratio.
* The benchmark uses a small rectangle with dimensions 1x1 pixels, which may not accurately represent more complex rendering scenarios.

**Alternatives**

Other approaches could be used to render a rectangle on a canvas element, such as:

* Using Web Workers for parallel processing
* Employing GPU-accelerated graphics APIs like WebGL or WebGPU
* Utilizing hardware acceleration through the `requestAnimationFrame` function

However, these alternatives would likely introduce additional complexity and may not provide significant performance benefits over the two options being compared in this benchmark.

Related benchmarks:

Using a global context variable versus getting the context on each draw call (version: 0)

Comparing performance of: Using a global context variable vs Invoking getContext() before every fillRect()

Created: 4 years ago by: Registered User

Jump to the latest result

Using a global context variable

Invoking getContext() before every fillRect()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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