Out of memory error java heap space using IOUtils.copyLarge . How can I fix this?

I have an application (Springboot api) that runs un kubernetes and i have a single instance with cpu:200m and memory:8Gi. My jvm parameters are : _JAVA_OPTIONS: -Xmx7G -Xms7G My goal is to copy one or more files of size between 30Mb and 1Gb from one s3 bucket to an other with presigned url.

I get java.lang.OutOfMemoryError: Java heap space error when i call my api more than 2 times in paralelle with 1 gb files.

Here is my code :

public ResponseEntity<String> transferData(Config config) throws IOException {

    var inputUrl = config.getInputdUrl();
    var outputUrl = config.getOutputdUrl();


    var uploadConnection = uploader.getUploadConnection(outputUrl);

    try (var inputStream = downloader.getDownloadConnection(inputUrl); 
         var outputStream = uploadConnection.getOutputStream()) {

        IOUtils.copyLarge(inputStream, outputStream);

        var resp = uploadConnection.getResponseCode();

        return ResponseEntity
                .status(HttpStatus.OK)
                .body("Transfer done with response:" + resp);
    } catch (IOException ioe) {
        return ResponseEntity
                .status(HttpStatus.INTERNAL_SERVER_ERROR)
                .body("An  error occurred while transferring data : " + ioe);
    }

}

getUploadConnection return HttpURLConnection :

        var connection = (HttpURLConnection) new URL(presignedUrl).openConnection();
        connection.setDoOutput(true);
        connection.setRequestMethod(PUT.toString());
        return connection;

getDownloadConnection return an HttpURLConnection inputStream.

        HttpURLConnection connection = (HttpURLConnection) new URL(presignedUrl).openConnection();
        connection.setRequestMethod(GET.toString());
        connection.setDoOutput(true);
return connection.getInputStream();

Regarding my code and my configuration, I though that the impact on memory would be less important as I stream the file and dont get it completly in memory.

What am i missing ?

EDIT 1: I added setChunkedStreamingMode so now my getUploadConnection return :

        var connection = (HttpURLConnection) new URL(url).openConnection();
        connection.setDoOutput(true);
        connection.setDoInput(true);
        connection.setChunkedStreamingMode(-1);
        connection.setRequestMethod(PUT.toString());
        return connection;

But i get an 411 error from my s3 bucket

With setFixedLengthStreamingMode set in my outPut connection, I was able to transfer more files without Out of memory error java heap space issues.

My output Connection :

var connection = (HttpURLConnection) new URL(presignedUrl).openConnection();
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setRequestMethod("PUT");
connection.setFixedLengthStreamingMode(downloadConnection.getContentLengthLong());