Benchmark: Map() delete while iterating vs clear

Script Preparation code:

var dummy = 0;
var map = new Map(new Array(100).fill(null).map((_, i) => [
  function(incrementBy) {
  	dummy += incrementBy;
  },
  { incrementBy: i }
]));

Tests:

Iterate + clear
for (const [fn, obj] of map) { fn(obj.incrementBy); } map.clear();
Iterate + delete
for (const [fn, obj] of map) { fn(obj.incrementBy); map.delete(fn); }

Historical Performance Data aggregated from 9 community runs

Desktop Results:

Chrome 9 runs

Iterate + delete

93.3M/s

Iterate + clear

11.1M/s

Fastest: Iterate + delete (8.4x faster)

View exact numbers

✓ Iterate + delete: 93,250,992 ops/sec
• Iterate + clear: 11,104,139 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Iterate + clear
Iterate + delete

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:149.0) Gecko/20100101 Firefox/149.0

Browser/OS: Firefox 149 on Linux

View result in a separate tab

Iterate + delete

25.6M/s

Iterate + clear

21.6M/s

View exact numbers

Test name	Executions per second
✓ Iterate + delete	25,586,444 Ops/sec
Iterate + clear	21,628,164 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark test and its options.

**Benchmark Test**

The benchmark test is designed to measure the performance difference between two approaches when iterating over a Map and clearing it afterwards:

1. **Iterate + Clear**: In this approach, the code iterates over the Map, calls each function associated with the key-value pairs, and then clears the entire Map.
2. **Iterate + Delete**: In this approach, the code iterates over the Map, calls each function associated with the key-value pairs, removes (deletes) the entry from the Map at each iteration step.

**Options Compared**

The two options being compared are:

* Iterating over the Map and clearing it afterwards
* Iterating over the Map and deleting entries at each iteration step

**Pros and Cons of Each Approach**

1. **Iterate + Clear**
	* Pros:
		+ Easier to understand and maintain, as the code is more straightforward.
		+ May be faster for smaller Maps due to reduced overhead of repeated deletions.
	* Cons:
		+ Inefficient for large Maps, as deleting entries repeatedly can lead to significant performance degradation.
		+ May cause memory fragmentation issues if the Map contains a large number of small entries.
2. **Iterate + Delete**
	* Pros:
		+ Can be faster for larger Maps, as it minimizes the overhead of repeated deletions.
		+ Reduces memory usage by avoiding unnecessary clearing of the Map.
	* Cons:
		+ More complex to understand and maintain, due to the need to delete entries at each iteration step.
		+ May cause performance issues if the Map contains a large number of small entries.

**Library Used**

None is explicitly mentioned in the provided benchmark definition JSON. However, it's likely that the `Map` data structure is part of the JavaScript standard library or a widely supported implementation.

**Special JS Feature/Syntax**

None are mentioned in the provided benchmark definition JSON.

**Other Alternatives**

If you need to optimize Map operations for performance, other approaches to consider:

1. **Using `forEach()`**: Instead of using `for...of` loops or `map()`, consider using `forEach()` with a callback function to iterate over the Map entries.
2. **Avoiding unnecessary deletions**: Consider optimizing your data structure to minimize the need for frequent deletions, such as by using a more efficient data structure like a binary search tree.
3. **Using caching or memoization**: If your functions perform expensive computations or access external resources, consider implementing caching or memoization mechanisms to reduce the overhead of repeated function calls.

Keep in mind that the best approach will depend on the specific requirements and constraints of your application.

Map() delete while iterating vs clear (version: 0) Benchmark.js

When iterating over a Map and clearing after iteration is required, is it faster to remove items at each iteration step or is it faster to iterate and then clear() the entire Map afterwards?

Comparing performance of: `Iterate + clear vs Iterate + delete`

Created: 4 years ago by: Guest

Go to the latest result

Iterate + clear

Iterate + delete

Historical Performance Data aggregated from 9 community runs

Desktop Results:

Chrome 9 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Map() delete while iterating vs clear (version: 0) Benchmark.js

When iterating over a Map and clearing after iteration is required, is it faster to remove items at each iteration step or is it faster to iterate and then clear() the entire Map afterwards?

Comparing performance of: Iterate + clear vs Iterate + delete

Created: 4 years ago by: Guest

Go to the latest result

Iterate + clear

Iterate + delete

Historical Performance Data aggregated from 9 community runs

Desktop Results:

Chrome 9 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `Iterate + clear vs Iterate + delete`