Modify default for max_new_tokens in python client (#1336)

# What does this PR do?
Since
([#1097](https://github.com/huggingface/text-generation-inference/pull/1097))
the clients do not need to specify a max_length anymore. However, the
python client in this repo had not yet been adapted to these changes.
This PR makes it possible to use the python client and not provide
max_new_tokens.

<!-- Remove if not applicable -->


## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the
other checks if that's the case).
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guideline](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md#start-contributing-pull-requests),
      Pull Request section?
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[forum](https://discuss.huggingface.co/)? Please add a link
      to it if that's the case.
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Here are the
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guidelines](https://github.com/huggingface/transformers/tree/main/docs),
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- [x] Did you write any new necessary tests?


## Who can review?

Anyone in the community is free to review the PR once the tests have
passed. Feel free to tag
members/contributors who may be interested in your PR.

clients/python/tests/test_client.py

@@ -21,6 +21,22 @@ def test_generate(flan_t5_xxl_url, hf_headers):
     assert not response.details.tokens[0].special
 
 
+def test_generate_max_new_tokens_not_set(flan_t5_xxl_url, hf_headers):
+    client = Client(flan_t5_xxl_url, hf_headers)
+    response = client.generate("test", decoder_input_details=True)
+
+    assert response.generated_text != ""
+    assert response.details.finish_reason == FinishReason.EndOfSequenceToken
+    assert response.details.generated_tokens > 1
+    assert response.details.seed is None
+    assert len(response.details.prefill) == 1
+    assert response.details.prefill[0] == InputToken(id=0, text="<pad>", logprob=None)
+    assert len(response.details.tokens) > 1
+    assert response.details.tokens[0].id == 3
+    assert response.details.tokens[0].text == " "
+    assert not response.details.tokens[0].special
+
+
 def test_generate_best_of(flan_t5_xxl_url, hf_headers):
     client = Client(flan_t5_xxl_url, hf_headers)
     response = client.generate(

clients/python/text_generation/client.py

@@ -62,7 +62,7 @@ class Client:
         self,
         prompt: str,
         do_sample: bool = False,
-        max_new_tokens: int = 20,
+        max_new_tokens: Optional[int] = None,
         best_of: Optional[int] = None,
         repetition_penalty: Optional[float] = None,
         return_full_text: bool = False,
@@ -157,7 +157,7 @@ class Client:
         self,
         prompt: str,
         do_sample: bool = False,
-        max_new_tokens: int = 20,
+        max_new_tokens: Optional[int] = None,
         repetition_penalty: Optional[float] = None,
         return_full_text: bool = False,
         seed: Optional[int] = None,
@@ -312,7 +312,7 @@ class AsyncClient:
         self,
         prompt: str,
         do_sample: bool = False,
-        max_new_tokens: int = 20,
+        max_new_tokens: Optional[int] = None,
         best_of: Optional[int] = None,
         repetition_penalty: Optional[float] = None,
         return_full_text: bool = False,
@@ -405,7 +405,7 @@ class AsyncClient:
         self,
         prompt: str,
         do_sample: bool = False,
-        max_new_tokens: int = 20,
+        max_new_tokens: Optional[int] = None,
         repetition_penalty: Optional[float] = None,
         return_full_text: bool = False,
         seed: Optional[int] = None,

clients/python/text_generation/types.py

@@ -9,7 +9,7 @@ class Parameters(BaseModel):
     # Activate logits sampling
     do_sample: bool = False
     # Maximum number of generated tokens
-    max_new_tokens: int = 20
+    max_new_tokens: Optional[int] = None
     # The parameter for repetition penalty. 1.0 means no penalty.
     # See [this paper](https://arxiv.org/pdf/1909.05858.pdf) for more details.
     repetition_penalty: Optional[float] = None