Defensive copies of payloads trigger G1 humongous allocations

[awelless]

Message constructor and getPayload() make defensive copies of large payloads, causing G1 humongous allocations

Describe the bug

Message makes two unconditional defensive copies of the payload byte array:

// Message.java — constructor
this.payload = requireNonNull(payload, "payload").clone();

// Message.java — getter
public byte[] getPayload() {
    return payload.clone();
}

On a dev machine (8 vCPUs, 18 GB heap) for payloads larger than ~8 MB (half of a 16 MB G1 region), each clone is a G1 humongous allocation and may directly trigger a GC cycle. Humongous allocations degrade the overall system performance.

Possible Solution

Should Message class has no-copy constructor and payload getter using which will reduce unnecessary memory allocations?

Additional details

There are more allocations, e.g. array allocation during decoding or underlying BAOS array resizing. But these were not present on JFR recordings.

Library version used

aws-eventstream 1.0.1 (via aws-sdk 2.41.24)

JDK version used

21.0.10

Operating System and version

Linux