GC scenario when producing a lot of large string buffers

Main.java

public class Main {

    private static String buildBigString (int numStrings) {
        StringBuffer sb = new StringBuffer();
        for(int i = 0; i < numStrings; i++) {
            sb.append("12345678");
            sb.append(",");
        }
        return sb.toString();
    }
    public static void main(String[] args) {
        long totalLength = 0L;
        for(int i = 0; i < 10000; i++) {
            String s = buildBigString(100000);
            totalLength = totalLength + s.length();
        }
        System.out.format("Built 100000 strings, total of %d length.\n", totalLength);
    }
}

Program.fs

open System

let buildBigString numStrings =
    let sb = System.Text.StringBuilder()
    for i in 1..numStrings do
        sb.Append("12345678") |> ignore
        sb.Append(",") |> ignore
    sb.ToString ()

[<EntryPoint>]
let main argv =
    let mutable totalLength = 0L
    for i in 1..10000 do
        let s = buildBigString 100000
        totalLength <- totalLength + int64 s.Length
    printfn "Built 100000 strings, total of %d length." totalLength
    0