具有输入和输出流的IOUtils.copy（）非常慢

Question

As part of my web service, I have a picture repository which retrieves an image from Amazon S3 (a datastore) then returns it. This is how the method that does this looks:

File getPicture(String path) throws IOException {
    File file = File.createTempFile(path, ".png");
    S3Object object = s3Client.getObject(new GetObjectRequest(bucketName, path));
    IOUtils.copy(object.getObjectContent(), new FileOutputStream(file));
    return file;
}

The problem is that it takes way too long to get a response from the service - (a 3MB image took 7.5 seconds to download). I notice that if I comment out the IOUtils.copy() line, the response time is significantly faster so it must be that particular method that's causing this delay.

I've seen this method used in almost all modern examples of converting an S3Object to a file but I seem to be a unique case. Am I missing a trick here?

Appreciate any help!

Answer 1

From the AWS documentation:

public S3Object getObject(GetObjectRequest getObjectRequest)

the returned Amazon S3 object contains a direct stream of data from the HTTP connection. The underlying HTTP connection cannot be reused until the user finishes reading the data and closes the stream.

public S3ObjectInputStream getObjectContent()

Note: The method is a simple getter and does not actually create a stream. If you retrieve an S3Object, you should close this input stream as soon as possible, because the object contents aren't buffered in memory and stream directly from Amazon S3.

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If you remove the IOUtils.copy line, then method exits quickly because you don't actually process the stream. If the file is large it will take time to download. You can't do much about that unless you can get a better connection to the AWS services.