Hi, I’m using Ktor server and the Ktor client to achieve the following. My API users request a file ...

# ktor

[Marcel Bochtler]

Hi, I’m using Ktor server and the Ktor client to achieve the following.
My API users request a file from my API. The Ktor client downloads this file and responds the file to the API user.
While this works using this code:

val fileChannel: ByteReadChannel = client.get("<https://example.com/bigfile.bin>").body()

call.response.header(
    HttpHeaders.ContentDisposition,
    ContentDisposition.Attachment.withParameter(
        ContentDisposition.Parameters.FileName,
        fileName
    ).toString()
)

call.respond(fileChannel)

the the Profiler shows that a large amount of memory is used by a byte[].
What do I miss here? Where is the ByteReadChannel converted into a byte array, and therefore read into memory?

[Aleksei Tirman [JB]]

The problem is that the get call reads the entire response body into memory. You can use the following code to stream the response body:

client.prepareGet("<https://example.com/bigfile.bin>").execute { response -> 
    call.respond(response.bodyAsChannel())
}