When profiling one of our Kafka consumers, I noticed that for every message a new HeapByteBuffer is allocated. This was surprising to me, because I thought they would be re-used, but it seems that the JsonFactory actually uses a new InputStreamReader for every byte array. And this InputStreamReader will use HeapByteBuffers for its internal buffering.

Is this something Jackson could do more elegantly by reusing the buffers? There seems to be no obvious way of reusing StreamDecoder, or InputStream reader, but since the source is known to be a byte array, there should be something better

Jackson version is 2.10.1.

(The API called in this screenshot is ObjectMapper.readValue(byte[]), but there seems to be no way to call this more efficiently since all calls end up in com.fasterxml.jackson.core.json.ByteSourceJsonBootstrapper.constructReader())