Summarization length not controlled by max_length, min_length

I am using the pertained ctrlsum-cnndm model from transformers. I noticed that summarization text length is not exactly controlled by max_length, min_length arguments of model.generate(). Not sure why. It appears that empty spaces are included, but not sure. Please help. Thanks.

text1="The tower is 324 metres (1,063 ft) tall, about the same height as an 81-storey building, and the tallest structure in Paris. Its base is square, measuring 125 metres (410 ft) on each side. During its construction, the Eiffel Tower surpassed the Washington Monument to become the tallest man-made structure in the world, a title it held for 41 years until the Chrysler Building in New York City was finished in 1930. It was the first structure to reach a height of 300 metres. Due to the addition of a broadcasting aerial at the top of the tower in 1957, it is now taller than the Chrysler Building by 5.2 metres (17 ft). Excluding transmitters, the Eiffel Tower is the second tallest free-standing structure in France after the Millau Viaduct."

from transformers import AutoTokenizer, AutoModelForSeq2SeqLM
tokenizer = AutoTokenizer.from_pretrained("hyunwoongko/ctrlsum-cnndm")
model = AutoModelForSeq2SeqLM.from_pretrained("hyunwoongko/ctrlsum-cnndm")

inputs = tokenizer.encode(text1, return_tensors="pt", max_length=1024)#16
outputs = model.generate(inputs, max_length=100, min_length=50, num_beams=5, early_stopping=True)
print(tokenizer.decode(outputs[0]))

Results: max_length=100, min_length=50, actually 36 words </s> The Eiffel Tower is 324 metres (1,063 ft) tall, about the same height as an 81-storey building. It is the tallest structure in Paris and the second tallest free-standing structure in France after the Millau Viaduct.</s>

max_length=200, min_length=100, actually 83 words </s> The Eiffel Tower is 324 metres (1,063 ft) tall, about the same height as an 81-storey building, and the tallest structure in Paris. It was the tallest man-made structure in the world for 41 years until the Chrysler Building in New York City was finished in 1930. It is the second tallest free-standing structure in France after the Millau Viaduct, which measures 125 metres (410 ft) on each side. The tower is now taller than the Chrysler building by 5.2 metres (17 ft)</s>

[LysandreJik]

cc @patil-suraj @patrickvonplaten

[chris-aeviator]

Stalebots are so much an anti-quality measure and have not been fixed