Benchmark: Map read/write once vs twice (dcfsdfsdf)

Script Preparation code:

var keys = [1, 2, 3, 4];
var mapObject = {};
var mapTime = {};
var mapDate = {};

Tests:

Once
const date = Date.now(); keys.forEach((key, i) => { const time = i * 1000; mapObject[key] = {time, date}; }); keys.forEach((key) => { const {time, date} = mapObject[key]; mapObject[key].date = 1; mapObject[key].time = 2; });
Twice
const date = Date.now(); keys.forEach((key, i) => { const time = i * 1000; mapTime[key] = time; mapDate[key] = date; }); keys.forEach((key) => { const a = mapTime[key]; const b = mapDate[key]; mapTime[key] = 1; mapDate[key] = 2; });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Once
Twice

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36

Browser/OS: Chrome 128 on Windows

View result in a separate tab

Test name	Executions per second
Once	1250204.4 Ops/sec
Twice	907267.6 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided JSON represents a JavaScript microbenchmarking test case, specifically designed to measure the performance difference between reading and writing to a Map object twice versus once.

**What is tested?**

Two different approaches are compared:

1. **Once**: Reading from the Map object once and then updating its values.
2. **Twice**: Reading from the Map object twice and then updating its values.

The benchmark measures the number of executions per second for each approach, providing insights into which method is more efficient in terms of performance.

**Options compared**

Two main options are being compared:

* **Read-Write Once (RWO)**: Reading from the Map object once and then updating its values.
* **Read-Write Twice (RW2)**: Reading from the Map object twice and then updating its values.

The pros and cons of each approach are:

**Read-Write Once (RWO)**

Pros:

* May be faster due to reduced number of iterations
* Less overhead from multiple reads

Cons:

* More memory accesses, potentially leading to higher cache miss rates
* Updates may require more work due to the need to re-compute values

**Read-Write Twice (RW2)**

Pros:

* Fewer memory accesses and cache misses compared to RWO
* Updates may be less expensive since only one iteration is performed

Cons:

* More iterations, potentially leading to higher overhead
* More function calls and memory allocations for repeated reads

**Library usage**

The benchmark uses a `Map` object, which is a JavaScript built-in data structure that stores key-value pairs. In this context, the Map object is used to store and update values.

No specific library or framework is being tested in this benchmark. The focus is on measuring the performance of the JavaScript engine itself, specifically with regards to reading from and updating a Map object.

**Special JS features**

This benchmark does not use any special JS features or syntax that would impact its results.

**Other alternatives**

To further improve performance, alternative approaches could be explored:

* Using an `Object` instead of a `Map`, as both have similar performance characteristics
* Implementing a custom data structure using techniques like hashing and caching
* Optimizing the update logic to reduce the number of operations

However, these alternatives would likely require significant changes to the benchmark code and may not necessarily improve performance.

**Benchmark preparation**

The provided script preparation code initializes three variables:

* `keys`: an array of numbers used as keys in the Map object
* `mapObject`, `mapTime`, and `mapDate`: objects used to store and update values

The script then iterates over the `keys` array, setting initial values for each key in the `mapObject`, `mapTime`, and `mapDate` objects. The second iteration updates the values in the Map object using the updated keys.

**Test case**

Each test case has a unique Benchmark Definition, which represents the JavaScript code executed by the benchmark:

* **Once**: Reads from the Map object once and then updates its values.
* **Twice**: Reads from the Map object twice and then updates its values.

Related benchmarks:

Map read/write once vs twice (dcfsdfsdf) (version: 1)

Comparing performance of: Once vs Twice

Created: one year ago by: Registered User

Jump to the latest result

Once

Twice

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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