convert_hf : fix memory leak in lazy MoE conversion

The '_lazy' queue was sometimes self-referential,
which caused reference cycles of objects old enough
to avoid garbage collection until potential memory exhaustion.

convert_hf_to_gguf.py

@@ -3456,20 +3456,19 @@ class LazyTorchTensor(gguf.LazyBase):
         dtype = self._dtype_map[self.dtype]
         return gguf.LazyNumpyTensor(
             meta=gguf.LazyNumpyTensor.meta_with_dtype_and_shape(dtype, self.shape),
-            lazy=self._lazy,
             args=(self,),
-            func=(lambda s: s[0].numpy())
+            func=(lambda s: s.numpy())
         )
 
     @classmethod
-    def meta_with_dtype_and_shape(cls, dtype: torch.dtype, shape: torch.Size) -> Tensor:
+    def meta_with_dtype_and_shape(cls, dtype: torch.dtype, shape: tuple[int, ...]) -> Tensor:
         return torch.empty(size=shape, dtype=dtype, device="meta")
 
     @classmethod
     def from_safetensors_slice(cls, st_slice: Any) -> Tensor:
         dtype = cls._dtype_str_map[st_slice.get_dtype()]
-        shape = st_slice.get_shape()
+        shape: tuple[int, ...] = tuple(st_slice.get_shape())
-        lazy = cls(meta=cls.meta_with_dtype_and_shape(dtype, shape), args=(st_slice,), func=lambda s: s[0][:])
+        lazy = cls(meta=cls.meta_with_dtype_and_shape(dtype, shape), args=(st_slice,), func=lambda s: s[:])
         return cast(torch.Tensor, lazy)
 
     @classmethod
@@ -3482,7 +3481,7 @@ class LazyTorchTensor(gguf.LazyBase):
         if func is torch.Tensor.numpy:
             return args[0].numpy()
 
-        return LazyTorchTensor._wrap_fn(func)(*args, **kwargs)
+        return cls._wrap_fn(func)(*args, **kwargs)
 
 
 def parse_args() -> argparse.Namespace:

gguf-py/gguf/lazy.py

@@ -3,7 +3,6 @@ from abc import ABC, ABCMeta, abstractmethod
 
 import logging
 from typing import Any, Callable
-from collections import deque
 
 import numpy as np
 from numpy.typing import DTypeLike
@@ -74,20 +73,18 @@ class LazyBase(ABC, metaclass=LazyMeta):
     _tensor_type: type
     _meta: Any
     _data: Any | None
-    _lazy: deque[LazyBase]  # shared within a graph, to avoid deep recursion when making eager
     _args: tuple
-    _func: Callable[[tuple], Any] | None
+    _kwargs: dict[str, Any]
+    _func: Callable[[Any], Any] | None
 
-    def __init__(self, *, meta: Any, data: Any | None = None, lazy: deque[LazyBase] | None = None, args: tuple = (), func: Callable[[tuple], Any] | None = None):
+    def __init__(self, *, meta: Any, data: Any | None = None, args: tuple = (), kwargs: dict[str, Any] | None = None, func: Callable[[Any], Any] | None = None):
         super().__init__()
         self._meta = meta
         self._data = data
-        self._lazy = lazy if lazy is not None else deque()
         self._args = args
+        self._kwargs = kwargs if kwargs is not None else {}
         self._func = func
         assert self._func is not None or self._data is not None
-        if self._data is None:
-            self._lazy.append(self)
 
     def __init_subclass__(cls) -> None:
         if "_tensor_type" not in cls.__dict__:
@@ -117,6 +114,7 @@ class LazyBase(ABC, metaclass=LazyMeta):
             args = ((use_self,) if use_self is not None else ()) + args
 
             meta_args = LazyBase._recurse_apply(args, lambda t: t._meta)
+            # TODO: maybe handle tensors in kwargs too
 
             if isinstance(meta_noop, bool) and not meta_noop:
                 try:
@@ -140,23 +138,7 @@ class LazyBase(ABC, metaclass=LazyMeta):
                         res = cls.meta_with_dtype_and_shape(meta_noop, res.shape)
 
             if isinstance(res, cls._tensor_type):
-                class CollectSharedLazy:
+                return cls(meta=cls.eager_to_meta(res), args=args, kwargs=kwargs, func=fn)
-                    # emulating a static variable
-                    shared_lazy: None | deque[LazyBase] = None
-
-                    @staticmethod
-                    def collect_replace(t: LazyBase):
-                        if CollectSharedLazy.shared_lazy is None:
-                            CollectSharedLazy.shared_lazy = t._lazy
-                        else:
-                            CollectSharedLazy.shared_lazy.extend(t._lazy)
-                            t._lazy = CollectSharedLazy.shared_lazy
-
-                LazyBase._recurse_apply(args, CollectSharedLazy.collect_replace)
-
-                shared_lazy = CollectSharedLazy.shared_lazy
-
-                return cls(meta=cls.eager_to_meta(res), lazy=shared_lazy, args=args, func=lambda a: fn(*a, **kwargs))
             else:
                 del res  # not needed
                 # non-tensor return likely relies on the contents of the args
@@ -168,26 +150,18 @@ class LazyBase(ABC, metaclass=LazyMeta):
     @classmethod
     def to_eager(cls, t: Any) -> Any:
         def simple_to_eager(_t: LazyBase) -> Any:
-            def already_eager_to_eager(_t: LazyBase) -> Any:
+            if _t._data is not None:
-                assert _t._data is not None
                 return _t._data
 
-            while _t._data is None:
+            # NOTE: there's a recursion limit in Python (usually 1000)
-                lt = _t._lazy.popleft()
+
-                if lt._data is not None:
+            assert _t._func is not None
-                    # Lazy tensor did not belong in the lazy queue.
+            _t._args = cls._recurse_apply(_t._args, simple_to_eager)
-                    # Weirdly only happens with Bloom models...
+            _t._data = _t._func(*_t._args, **_t._kwargs)
-                    # likely because tensors aren't unique in the queue.
+            # sanity check
-                    # The final output is still the same as in eager mode,
+            assert _t._data is not None
-                    # so it's safe to ignore this.
+            assert _t._data.dtype == _t._meta.dtype
-                    continue
+            assert _t._data.shape == _t._meta.shape
-                assert lt._func is not None
-                lt._args = cls._recurse_apply(lt._args, already_eager_to_eager)
-                lt._data = lt._func(lt._args)
-                # sanity check
-                assert lt._data is not None
-                assert lt._data.dtype == lt._meta.dtype
-                assert lt._data.shape == lt._meta.shape
 
             return _t._data
 
@@ -206,7 +180,7 @@ class LazyBase(ABC, metaclass=LazyMeta):
     @classmethod
     def from_eager(cls, t: Any) -> Any:
         if type(t) is cls:
-            # already eager
+            # already lazy
             return t
         elif isinstance(t, cls._tensor_type):
             return cls(meta=cls.eager_to_meta(t), data=t)
@@ -228,8 +202,7 @@ class LazyNumpyTensor(LazyBase):
     def astype(self, dtype, *args, **kwargs):
         meta = type(self).meta_with_dtype_and_shape(dtype, self._meta.shape)
         full_args = (self, dtype,) + args
-        # very important to pass the shared _lazy deque, or else there's an infinite loop somewhere.
+        return type(self)(meta=meta, args=full_args, kwargs=kwargs, func=(lambda a, *args, **kwargs: a.astype(*args, **kwargs)))
-        return type(self)(meta=meta, args=full_args, lazy=self._lazy, func=(lambda a: a[0].astype(*a[1:], **kwargs)))
 
     def tofile(self, *args, **kwargs):
         eager = LazyNumpyTensor.to_eager(self)