convert-hf : save memory with lazy evaluation

gguf-py/gguf/gguf_writer.py

@@ -7,7 +7,7 @@ import struct
 import tempfile
 from enum import Enum, auto
 from io import BufferedWriter
-from typing import IO, Any, Sequence, Mapping
+from typing import IO, Any, Callable, Sequence, Mapping
 from string import ascii_letters, digits
 
 import numpy as np
@@ -28,6 +28,47 @@ from .constants import (
 logger = logging.getLogger(__name__)
 
 
+class LazyTensor:
+    data: Callable[[], np.ndarray[Any, Any]]
+    # to avoid too deep recursion
+    functions: list[Callable[[np.ndarray[Any, Any]], np.ndarray[Any, Any]]]
+    dtype: np.dtype[Any]
+    shape: tuple[int, ...]
+
+    def __init__(self, data: Callable[[], np.ndarray[Any, Any]], *, dtype: type, shape: tuple[int, ...]):
+        self.data = data
+        self.functions = []
+        self.dtype = np.dtype(dtype)
+        self.shape = shape
+
+    def astype(self, dtype: type, **kwargs) -> LazyTensor:
+        self.functions.append(lambda n: n.astype(dtype, **kwargs))
+        self.dtype = np.dtype(dtype)
+        return self
+
+    @property
+    def nbytes(self) -> int:
+        size = 1
+        for n in self.shape:
+            size *= n
+        return size * self.dtype.itemsize
+
+    def tofile(self, *args, **kwargs) -> None:
+        data = self.data()
+        for f in self.functions:
+            data = f(data)
+        assert data.shape == self.shape
+        assert data.dtype == self.dtype
+        assert data.nbytes == self.nbytes
+        self.functions = []
+        self.data = lambda: data
+        data.tofile(*args, **kwargs)
+
+    def byteswap(self, *args, **kwargs) -> LazyTensor:
+        self.functions.append(lambda n: n.byteswap(*args, **kwargs))
+        return self
+
+
 class WriterState(Enum):
     EMPTY   = auto()
     HEADER  = auto()
@@ -38,7 +79,7 @@ class WriterState(Enum):
 class GGUFWriter:
     fout: BufferedWriter
     temp_file: tempfile.SpooledTemporaryFile[bytes] | None
-    tensors: list[np.ndarray[Any, Any]]
+    tensors: list[np.ndarray[Any, Any] | LazyTensor]
     _simple_value_packing = {
         GGUFValueType.UINT8:   "B",
         GGUFValueType.INT8:    "b",
@@ -237,7 +278,7 @@ class GGUFWriter:
         self.ti_data_count += 1
 
     def add_tensor(
-        self, name: str, tensor: np.ndarray[Any, Any], raw_shape: Sequence[int] | None = None,
+        self, name: str, tensor: np.ndarray[Any, Any] | LazyTensor, raw_shape: Sequence[int] | None = None,
         raw_dtype: GGMLQuantizationType | None = None,
     ) -> None:
         if self.endianess == GGUFEndian.BIG:
@@ -262,7 +303,7 @@ class GGUFWriter:
         if pad != 0:
             fp.write(bytes([0] * pad))
 
-    def write_tensor_data(self, tensor: np.ndarray[Any, Any]) -> None:
+    def write_tensor_data(self, tensor: np.ndarray[Any, Any] | LazyTensor) -> None:
         if self.state is not WriterState.TI_DATA:
             raise ValueError(f'Expected output file to contain tensor info, got {self.state}')
 
@@ -272,15 +313,33 @@ class GGUFWriter:
         tensor.tofile(self.fout)
         self.write_padding(self.fout, tensor.nbytes)
 
-    def write_tensors_to_file(self) -> None:
+    def write_tensors_to_file(self, *, progress: bool = False) -> None:
         self.write_ti_data_to_file()
 
         self.write_padding(self.fout, self.fout.tell())
 
         if self.temp_file is None:
+            self.tensors.reverse()  # to pop from the "beginning" in constant time
+
+            if progress:
+                from tqdm import tqdm
+
+                total_bytes = sum(t.nbytes for t in self.tensors)
+
+                bar = tqdm(desc="Writing", total=total_bytes, unit="byte", unit_scale=True)
+
+                while True:
+                    try:
+                        tensor = self.tensors.pop()
+                    except IndexError:
+                        break
+                    tensor.tofile(self.fout)
+                    bar.update(tensor.nbytes)
+                    self.write_padding(self.fout, tensor.nbytes)
+                return
             while True:
                 try:
-                    tensor = self.tensors.pop(0)
+                    tensor = self.tensors.pop()
                 except IndexError:
                     break
                 tensor.tofile(self.fout)