"ArrayType" takes too large heap memory.

[sookie030]

I want to use ArrayType in ffi.
but ArrayType arrays take large memory abnormally.

My code is below.

let uint8Array = ArrayType('uint8');

console.log("start")
printHeapUsed();

let vectors = uint8Array(1);
console.log("create uint8Array(1)")
printHeapUsed()

vectors = uint8Array(10);
console.log("create uint8Array(10)")
printHeapUsed()

vectors = uint8Array(100);
console.log("create uint8Array(100)")
printHeapUsed()

vectors = uint8Array(1000);
console.log("create uint8Array(1000)")
printHeapUsed()

vectors = uint8Array(10000);
console.log("create uint8Array(10000)")
printHeapUsed()

vectors = uint8Array(100000);
console.log("create uint8Array(100000)")
printHeapUsed()

vectors = uint8Array(1000000);
console.log("create uint8Array(1000000)")
printHeapUsed()

// print used heap
function printHeapUsed() {
    let used = process.memoryUsage().heapUsed / 1024 / 1024;
    if (used < 1000)
        console.log(`heapUsed: ${Math.round(used * 100) / 100} MB\n`);
    else {
        used = used / 1024;
        console.log(`heapUsed: ${Math.round(used * 100) / 100} GB\n`);
    }
}

and result in console..

start
heapUsed: 4.53 MB

create uint8Array(1)
heapUsed: 4.56 MB

create uint8Array(10)
heapUsed: 4.57 MB

create uint8Array(100)
heapUsed: 4.62 MB

create uint8Array(1000)
heapUsed: 5.02 MB

create uint8Array(10000)
heapUsed: 8.85 MB

create uint8Array(100000)
heapUsed: 49.53 MB

create uint8Array(1000000)
heapUsed: 390.3 MB

ArrayType(ref.types.uint8).BYTES_PER_ELEMENT == 1
and I think the used heap is about 1MB with uint8Array(1000) but not.

Please tell me why. thanks.