Why once a GPUCommandBuffer object has been submitted, it cannot be used again?
And is it possible to make a copy of the unsubmitted GPUCommandBuffer?
I wish I could put createCommandEncoder() and beginXXXPass() in the initialization.
Like this:

var commandBuffer;

function init(){
  var commandEncoder = device.createCommandEncoder();
  var pass = commandEncoder.beginXXXPass();
  pass.end();
  commandBuffer = commandEncoder.finish();
}

function process(){
  var buffer = commandBuffer.copy(); //Is it possible to make a copy of the unsubmitted GPUCommandBuffer like this?
  device.queue.submit([buffer]);
}

I know that GPURenderBundle has similar functionality, but it doesn't work for compute pass.
Why not reuse GPUCommandBuffer or GPUCommandEncoder?