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fix stop detections #1392

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Merged
suquark merged 7 commits into from
May 22, 2023
Merged

fix stop detections #1392

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c083920
fix stop detections
mingfang May 20, 2023
dfde374
rename to partial_stop and add comment
mingfang May 20, 2023
101438e
refine partial_stop()
mingfang May 21, 2023
3c40b62
avoid using same partial_stop name for both flag and function
mingfang May 21, 2023
cc906f4
make partial_stop() global
mingfang May 21, 2023
fde31b8
default partially_stopped to False when stop_str is False
mingfang May 21, 2023
ffe382f
default partially_stopped to False
mingfang May 21, 2023
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37 changes: 27 additions & 10 deletions fastchat/serve/inference.py
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,13 @@ def prepare_logits_processor(
return processor_list


def partial_stop(output, stop_str):
for i in range(0, min(len(output), len(stop_str))):
if stop_str.startswith(output[-i:]):
return True
return False


@torch.inference_mode()
def generate_stream(
model, tokenizer, params, device, context_len=2048, stream_interval=2
Expand Down Expand Up @@ -160,31 +167,41 @@ def generate_stream(
skip_special_tokens=True,
spaces_between_special_tokens=False,
)

partially_stopped = False
if stop_str:
if isinstance(stop_str, str):
pos = output.rfind(stop_str, rfind_start)
if pos != -1:
output = output[:pos]
stopped = True
else:
partially_stopped = partial_stop(output, stop_str)
elif isinstance(stop_str, Iterable):
for each_stop in stop_str:
pos = output.rfind(each_stop, rfind_start)
if pos != -1:
output = output[:pos]
stopped = True
break
else:
partially_stopped = partial_stop(output, each_stop)
if partially_stopped:
break
else:
raise ValueError("Invalid stop field type.")

yield {
"text": output,
"usage": {
"prompt_tokens": input_echo_len,
"completion_tokens": i,
"total_tokens": input_echo_len + i,
},
"finish_reason": None,
}

# prevent yielding partial stop sequence
if not partially_stopped:
yield {
"text": output,
"usage": {
"prompt_tokens": input_echo_len,
"completion_tokens": i,
"total_tokens": input_echo_len + i,
},
"finish_reason": None,
}

if stopped:
break
Expand Down