Performing any long running task or CPU intensive work on transport_worker threads is problematic. This is typically very bad for cluster stability.

This issue has been filed to examine the usage of transport_worked threads by ESQL, with the intention of "offloading" as much as possible, including deserialising large(ish) amounts of data.
x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plugin/ComputeService.java
DataNodeResponse() {}
        DataNodeResponse(StreamInput in) throws IOException {
            super(in);
        }
        @Override
        public void writeTo(StreamOutput out) {
        }
    }
    
    public static final String DATA_ACTION_NAME = EsqlQueryAction.NAME + "/data";
    private class DataNodeRequestHandler implements TransportRequestHandler<DataNodeRequest> {
        @Override
        public void messageReceived(DataNodeRequest request, TransportChannel channel, Task task) {
            final var parentTask = (CancellableTask) task;