The FeatureWriter releases the features to the output ports when all of them are written. Holding a large number of features eats up memory.
It is normal for some formats. However there are formats (eg. databases) where features are written one by one or in small groups. Releasing the features from these writers would make the FeatureWriter non-blocking and could decrease memory usage. The summary port could still be released at the end like Cumulative and Summary ports of the StatisticsCalculator.

