generation should be fixed now

This commit is contained in:
Goekdeniz-Guelmez 2025-03-09 00:16:40 +01:00
parent 46d6146102
commit 0bc2a881ad

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@ -57,228 +57,6 @@ class GRPOTrainingArgs(TrainingArgs):
)
def generate_step(
prompt: mx.array,
model: nn.Module,
*,
max_tokens: int = 256,
sampler: Optional[Callable[mx.array, mx.array]] = None,
logits_processors: Optional[List[Callable[[mx.array, mx.array], mx.array]]] = None,
max_kv_size: Optional[int] = None,
prompt_cache: Optional[Any] = None,
prefill_step_size: int = 512,
prompt_progress_callback: Optional[Callable[int, int]] = None,
) -> Generator[Tuple[mx.array, mx.array], None, None]:
"""
A generator producing token ids based on the given prompt from the model.
Args:
prompt (mx.array): The input prompt.
model (nn.Module): The model to use for generation.
max_tokens (int): The maximum number of tokens. Use``-1`` for an infinite
generator. Default: ``256``.
sampler (Callable[mx.array, mx.array], optional): A sampler for sampling a
token from a vector of log probabilities. Default: ``None``.
logits_processors (List[Callable[[mx.array, mx.array], mx.array]], optional):
A list of functions that take tokens and logits and return the processed
logits. Default: ``None``.
max_kv_size (int, optional): Maximum size of the key-value cache. Old
entries (except the first 4 tokens) will be overwritten.
prompt_cache (List[Any], optional): A pre-computed prompt cache. Note, if
provided, the cache will be updated in place.
prefill_step_size (int): Step size for processing the prompt.
kv_bits (int, optional): Number of bits to use for KV cache quantization.
None implies no cache quantization. Default: ``None``.
kv_group_size (int): Group size for KV cache quantization. Default: ``64``.
quantized_kv_start (int): Step to begin using a quantized KV cache.
when ``kv_bits`` is non-None. Default: ``0``.
prompt_prorgress_callback (Callable[int, int]): A call-back which takes the
prompt tokens processed so far and the total number of prompt tokens.
Yields:
Tuple[mx.array, mx.array]: One token and a vector of log probabilities.
"""
y = prompt
tokens = None
# Create the KV cache for generation
if prompt_cache is None:
prompt_cache = cache.make_prompt_cache(
model,
max_kv_size=max_kv_size,
)
elif len(prompt_cache) != len(model.layers):
raise ValueError("Wrong number of layers in the prompt cache.")
prompt_progress_callback = prompt_progress_callback or (lambda *_: None)
sampler = sampler or (lambda x: mx.argmax(x, axis=-1))
def _step(y):
with mx.stream(generation_stream):
logits = model(y[None], cache=prompt_cache)
logits = logits[:, -1, :]
if logits_processors:
nonlocal tokens
tokens = mx.concat([tokens, y]) if tokens is not None else y
for processor in logits_processors:
logits = processor(tokens, logits)
logprobs = logits - mx.logsumexp(logits, keepdims=True)
y = sampler(logprobs)
return mx.stop_gradient(y), mx.stop_gradient(logprobs.squeeze(0))
with mx.stream(generation_stream):
total_prompt_tokens = y.size
prompt_processed_tokens = 0
while y.size > prefill_step_size:
model(y[:prefill_step_size][None], cache=prompt_cache)
mx.eval([c.state for c in prompt_cache])
prompt_progress_callback(prompt_processed_tokens, total_prompt_tokens)
prompt_processed_tokens += prefill_step_size
y = y[prefill_step_size:]
mx.metal.clear_cache()
y, logprobs = _step(y)
mx.eval(y, logprobs)
n = 0
while True:
if n != max_tokens:
next_y, next_logprobs = _step(y)
mx.eval(next_y, next_logprobs)
if n == 0:
mx.eval(y)
prompt_progress_callback(total_prompt_tokens, total_prompt_tokens)
if n == max_tokens:
break
yield y.item(), logprobs
if n % 256 == 0:
mx.metal.clear_cache()
y, logprobs = next_y, next_logprobs
n += 1
def generate_grpo(
model: nn.Module,
prompts,
max_tokens,
tokenizer,
group_size,
end_token: str = "</answer>",
temperature: float = 0.8,
batch_size: int = 1,
):
try:
import time
start_time = time.time()
if len(prompts.shape) == 1:
prompts = prompts[None, :]
if prompts.shape[1] == 0:
return None
total_samples = prompts.shape[0] * group_size
expanded_prompts = mx.repeat(prompts, group_size, axis=0)
end_sequence = mx.array(tokenizer.encode(end_token))
results = []
mx.eval(expanded_prompts, results)
print(f"Setup time: {time.time() - start_time:.2f}s")
print(f"Generating {total_samples} samples with max_tokens={max_tokens}")
total_tokens_generated = 0
generation_start_time = time.time()
# Process in batches
for batch_start in range(0, total_samples, batch_size):
batch_end = min(batch_start + batch_size, total_samples)
batch_time = time.time()
print(
f"Starting batch {batch_start//batch_size + 1}/{(total_samples + batch_size - 1)//batch_size}: samples {batch_start}-{batch_end-1}"
)
# Custom sampler function that handles temperature
def temp_sampler(logits):
return mx.random.categorical(logits / temperature)
# Batched processing
for idx in range(batch_start, batch_end):
sample_start_time = time.time()
current_tokens = []
prompt_cache = cache.make_prompt_cache(model)
# The generate_step function yields one token at a time
# We'll collect tokens until we hit max_tokens or a stopping condition
for i, (token, _) in enumerate(
generate_step(
expanded_prompts[idx],
model,
max_tokens=max_tokens, # This is the maximum number of steps
sampler=temp_sampler,
prompt_cache=prompt_cache,
)
):
# Check for EOS token
if token == tokenizer.eos_token_id:
break
current_tokens.append(token)
print(token)
# Check for end token
if len(current_tokens) >= len(end_sequence) and mx.array_equal(
mx.array(current_tokens[-len(end_sequence) :]), end_sequence
):
break
# Check if we've reached the maximum number of tokens
if i >= max_tokens - 1:
break
mx.metal.clear_cache()
mx.eval(current_tokens)
if current_tokens:
results.append(mx.array(current_tokens))
total_tokens_generated += len(current_tokens)
sample_time = time.time() - sample_start_time
tokens_per_second = (
len(current_tokens) / sample_time if sample_time > 0 else 0
)
print(
f" Sample {idx}: Generated {len(current_tokens)} tokens in {sample_time:.2f}s ({tokens_per_second:.2f} tokens/sec)"
)
batch_time = time.time() - batch_time
print(f"Batch completed in {batch_time:.2f}s")
mx.metal.clear_cache()
generation_time = time.time() - generation_start_time
avg_tokens_per_second = (
total_tokens_generated / generation_time if generation_time > 0 else 0
)
print(
f"Generation complete: {total_tokens_generated} tokens in {generation_time:.2f}s"
)
print(f"Average generation speed: {avg_tokens_per_second:.2f} tokens/sec")
results = [mx.stop_gradient(r) for r in results]
mx.eval(results)
return results
except Exception as e:
print(f"Generation error: {str(e)}")
return None
def get_per_token_logps(model: nn.Module, inputs, lengths):
logits = model(inputs).astype(mx.float16)
logits = logits[:, :-1, :]
@ -297,75 +75,124 @@ def get_per_token_logps(model: nn.Module, inputs, lengths):
return per_token_logps
def generate_without_gradients(
def generate_step(
prompt: mx.array,
model: nn.Module,
max_tokens: int = 256,
sampler: Optional[Callable] = None,
logits_processors: Optional[List[Callable]] = None,
max_kv_size: Optional[int] = None,
prompt_cache: Optional[Any] = None,
) -> Generator[Tuple[mx.array, mx.array], None, None]:
tokens = None
y = prompt
if prompt_cache is None:
prompt_cache = cache.make_prompt_cache(model, max_kv_size=max_kv_size)
def _step(y):
with mx.stream(generation_stream):
logits = model(y[None], cache=prompt_cache)
logits = logits[:, -1, :]
if logits_processors:
nonlocal tokens
tokens = mx.concat([tokens, y]) if tokens is not None else y
for processor in logits_processors:
logits = processor(tokens, logits)
logprobs = logits - mx.logsumexp(logits, keepdims=True)
next_token = sampler(logprobs)
return mx.stop_gradient(next_token), mx.stop_gradient(logprobs.squeeze(0))
try:
with mx.stream(generation_stream):
y, logprobs = _step(y)
mx.eval(y, logprobs)
for n in range(max_tokens):
yield y.item(), logprobs
next_y, next_logprobs = _step(y)
mx.eval(next_y, next_logprobs)
y, logprobs = next_y, next_logprobs
if (n + 1) % 32 == 0:
mx.metal.clear_cache()
finally:
mx.metal.clear_cache()
def generate_grpo(
model: nn.Module,
tokenizer,
prompt_tokens,
max_tokens: int,
group_size: int,
end_token: str = "</answer>",
temperature: float = 0.8,
batch_size: int = 1
batch_size: int = 1,
):
"""Generate completions without tracking gradients"""
try:
end_sequence = mx.array(tokenizer.encode(end_token))
total_samples = len(prompt_tokens)
all_completions = []
all_completion_texts = []
batch_indices = []
# Store original state
was_training = model.training
def temp_sampler(logits):
return mx.random.categorical(logits / temperature)
# Force eval mode
model.eval()
for i in range(0, total_samples, batch_size):
current_batch_size = min(batch_size, total_samples - i)
batch_prompts = prompt_tokens[i : i + current_batch_size]
# Prepare prompts
total_samples = len(prompt_tokens)
all_completions = []
all_completion_texts = []
batch_indices = []
max_prompt_len = max(len(p) for p in batch_prompts)
padded_prompts = []
for prompt in batch_prompts:
padding = [tokenizer.pad_token_id] * (max_prompt_len - len(prompt))
padded_prompts.append(prompt + padding)
# Process in smaller batches
for i in range(0, total_samples, batch_size):
current_batch_size = min(batch_size, total_samples - i)
batch_prompts = prompt_tokens[i : i + current_batch_size]
prompt_tensor = mx.stop_gradient(mx.array(padded_prompts))
# Pad sequences to the same length
max_prompt_len = max(len(p) for p in batch_prompts)
padded_prompts = []
if len(prompt_tensor.shape) == 1:
prompt_tensor = prompt_tensor[None, :]
if prompt_tensor.shape[1] == 0:
continue
for prompt in batch_prompts:
padding = [tokenizer.pad_token_id] * (max_prompt_len - len(prompt))
padded_prompts.append(prompt + padding)
expanded_prompts = mx.repeat(prompt_tensor, group_size, axis=0)
batch_results = []
# Convert to tensor and explicitly stop gradient
prompt_tensor = mx.stop_gradient(mx.array(padded_prompts))
total_prompt_samples = expanded_prompts.shape[0]
for prompt_idx in range(total_prompt_samples):
current_tokens = []
prompt_cache = cache.make_prompt_cache(model)
try:
completions = generate_grpo(
model,
prompt_tensor,
max_tokens,
tokenizer,
group_size,
temperature=temperature,
batch_size=current_batch_size,
)
for token, _ in generate_step(
expanded_prompts[prompt_idx],
model,
max_tokens=max_tokens,
sampler=temp_sampler,
prompt_cache=prompt_cache,
):
if token == tokenizer.eos_token_id:
break
if completions is not None:
for j, completion_ids in enumerate(completions):
current_tokens.append(token)
if len(current_tokens) >= len(end_sequence) and mx.array_equal(
mx.array(current_tokens[-len(end_sequence):]), end_sequence
):
break
if current_tokens:
batch_results.append(mx.array(current_tokens))
if batch_results:
for j, completion_ids in enumerate(batch_results):
prompt_idx = i + (j // group_size)
if prompt_idx < total_samples:
batch_indices.append(prompt_idx)
completion_text = tokenizer.decode(completion_ids.tolist())
all_completions.append(completion_ids)
all_completions.append(mx.stop_gradient(completion_ids))
all_completion_texts.append(completion_text)
mx.eval(completion_ids)
except Exception as e:
print(f"Generation error: {e}")
continue
# Restore original state
if was_training:
model.train()
mx.metal.clear_cache()
mx.metal.clear_cache()
finally:
mx.metal.clear_cache()
return all_completions, all_completion_texts, batch_indices
@ -375,6 +202,9 @@ def grpo_loss(
ref_model,
tokenizer,
batch,
completions=None,
completion_texts=None,
batch_indices=None,
reward_funcs: Optional[List[RewardFunctions]] = None,
beta: float = 0.1,
group_size: int = 4,
@ -387,35 +217,35 @@ def grpo_loss(
):
prompt_tokens, _, prompt_text, answer_text = batch
# Generate completions without tracking gradients
all_completions, all_completion_texts, batch_indices = generate_without_gradients(
model=model,
tokenizer=tokenizer,
prompt_tokens=prompt_tokens,
max_tokens=max_tokens,
group_size=group_size,
temperature=temperature,
batch_size=batch_size
)
if completions is not None and completion_texts is not None and batch_indices is not None:
all_completions = completions
all_completion_texts = completion_texts
batch_indices = batch_indices
else:
all_completions, all_completion_texts, batch_indices = generate_grpo(
model=model,
tokenizer=tokenizer,
prompt_tokens=prompt_tokens,
max_tokens=max_tokens,
group_size=group_size,
temperature=temperature,
batch_size=batch_size
)
# If we didn't generate any completions, return early
if not all_completions:
raise ValueError(
"No completions were generated. Please check your model and inputs."
)
# Create expanded prompts and answers based on actual generated completions
expanded_answers = []
expanded_prompts = []
# Group completions by their original prompt
unique_prompt_indices = sorted(set(batch_indices))
grouped_completions = {idx: [] for idx in unique_prompt_indices}
for i, completion_idx in enumerate(batch_indices):
grouped_completions[completion_idx].append(i)
# Rebuild completions in the correct order
ordered_completions = []
ordered_completion_texts = []
ordered_batch_indices = []
@ -426,8 +256,6 @@ def grpo_loss(
ordered_completions.append(all_completions[idx])
ordered_completion_texts.append(all_completion_texts[idx])
ordered_batch_indices.append(prompt_idx)
# Add corresponding prompt and answer
expanded_prompts.append(prompt_text[prompt_idx])
expanded_answers.append(answer_text[prompt_idx])
@ -435,14 +263,11 @@ def grpo_loss(
all_completion_texts = ordered_completion_texts
batch_indices = ordered_batch_indices
# Create new input tensors for the model to compute logits with gradient tracking
max_length = max(ids.shape[0] for ids in all_completions)
padded_completions = []
attention_masks = []
for completion_ids in all_completions:
# Convert the pre-generated completion to a regular tensor (not stop_gradient)
# This allows gradients to flow during the loss computation phase
completion_tensor = mx.array(completion_ids.tolist())
padding_length = max_length - completion_tensor.shape[0]
@ -458,12 +283,10 @@ def grpo_loss(
padded_completions.append(padded_ids)
attention_masks.append(mask)
# Rest of the function remains the same
inputs = mx.stack(padded_completions)
attention_mask = mx.stack(attention_masks)
lengths = attention_mask.sum(axis=1)
# Current policy probabilities
token_log_probs = get_per_token_logps(model, inputs, lengths)
mx.eval(token_log_probs)
@ -487,10 +310,8 @@ def grpo_loss(
token_log_probs = mx.stack(padded_log_probs)
ref_token_log_probs = mx.stack(padded_ref_log_probs)
# Create array to store rewards from each function
all_func_rewards = []
# Collect rewards from each function separately
for reward_func in reward_funcs:
func_rewards = mx.array(
reward_func(
@ -501,10 +322,8 @@ def grpo_loss(
)
all_func_rewards.append(func_rewards)
# Stack rewards to shape (num_samples, num_funcs)
rewards = mx.stack(all_func_rewards, axis=1)
# Apply weights and sum
if reward_weights is not None:
if len(reward_weights) != len(reward_funcs):
raise ValueError(
@ -517,24 +336,19 @@ def grpo_loss(
rewards = (rewards * mx.expand_dims(reward_weights, 0)).sum(axis=1)
# Get number of unique prompts
num_unique_prompts = len(unique_prompt_indices)
# Reshape rewards based on actual groups
rewards_by_prompt = [[] for _ in range(num_unique_prompts)]
for i, prompt_idx in enumerate(batch_indices):
prompt_position = unique_prompt_indices.index(prompt_idx)
rewards_by_prompt[prompt_position].append(rewards[i])
# Calculate advantages within each group
advantages = mx.zeros_like(rewards)
for i, prompt_rewards in enumerate(rewards_by_prompt):
if len(prompt_rewards) > 1: # Only normalize if we have multiple samples
if len(prompt_rewards) > 1:
prompt_rewards = mx.array(prompt_rewards)
mean_reward = mx.mean(prompt_rewards)
std_reward = mx.std(prompt_rewards)
# Find indices for this prompt
indices = [
j
for j, idx in enumerate(batch_indices)
@ -545,7 +359,6 @@ def grpo_loss(
std_reward + epsilon
)
else:
# If only one sample, advantage is 0
idx = batch_indices.index(unique_prompt_indices[i])
advantages[idx] = 0.0
@ -746,6 +559,7 @@ def evaluate_grpo(
ref_model=ref_model,
temperature=temperature,
max_tokens=max_tokens,
is_validation=True
)
all_losses += losses * toks
@ -803,21 +617,37 @@ def train_grpo(
state = [model.state, optimizer.state]
def step(batch):
# Extract prompt tokens from the batch
prompt_tokens, targets, prompt_lens, target_lens = batch
# First, generate completions without gradient tracking
# The model will be frozen during this call
all_completions, all_completion_texts, batch_indices = generate_grpo(
model=model,
tokenizer=tokenizer,
prompt_tokens=prompt_tokens,
max_tokens=args.max_completion_length,
group_size=args.group_size,
temperature=args.temperature
)
# Now calculate loss and gradients with pre-generated completions
# We need to update loss_fn to accept these pre-generated completions
(loss, toks, metrics), grad = loss_value_and_grad(
model,
tokenizer=tokenizer,
batch=batch,
batch=(prompt_tokens, targets, prompt_lens, target_lens),
completions=all_completions,
completion_texts=all_completion_texts,
batch_indices=batch_indices,
reward_funcs=reward_funcs,
beta=args.beta,
group_size=args.group_size,
epsilon=args.epsilon,
ref_model=ref_model,
max_tokens=args.max_completion_length,
temperature=args.temperature,
)
grad = average_gradients(grad)
optimizer.update(model, grad)
return loss, toks, metrics