private void closeSafely(@Nullable Closeable obj) {
      try {
        if (obj != null) {
          obj.close();
        }
      } catch (IOException ioe) {
        throw new RuntimeException(ioe);
      }
    }
Starts next producer if it is not started yet and there is at least one Consumer waiting for
the data. If all consumers are cancelled, then this multiplexer is removed from mRequest map
to clean up.
imagepipeline/src/main/java/com/facebook/imagepipeline/producers/MultiplexProducer.java