Thread-safe buffer with list

Question

I have the following small class here:

class MyBuffer():
  def __init__(self):
    self.buffer = []
    self.thread = threading.Thread(target=self.process)
    self.thread.start()

  def pop_all(self):
    result, self.buffer = self.buffer, []
    return result

  def process(self):
    while True:
      current_buffer = self.pop_all()
      # Do something with current_buffer
      time.sleep(60)

  def append_buffer(self, param):
    self.buffer.append(param)

The append_buffer will be called at some part of the application to add items to the list. While the process method runs every 60 seconds to get all the items, clear the buffer and process those items that were buffered.

The question if the pop_all method is thread safe here? If not what would be a better approach?