_safetensors.py

# ran into memory issues with safetensors. this code moves by them.
import contextlib, json, mmap, os

import torch

class WritingSafeTensors:
    def __init__(self, name, file_size=16*1024*1024*1024, **metadata):
        self.name = name.removesuffix('.safetensors')
        self.metadata = metadata
        self.file = self.File(self.name + '.safetensors')
        self.files = {self.file.filename:self.file}
        self.file_size = file_size
        self.total_size = 0
        self.weight_map = {}
    def add(self, name, tensor):
        print(name, '...')
        self.weight_map[name] = self.file
        self.file.add(name, tensor)
        if self.file.size >= self.file_size:
            import pdb; pdb.set_trace()
            '''BUG WHERE ONE TENSOR IS DROPPED'''
            self.file.undo(name, tensor)
            ct = len(self.files)
            if len(self.files) == 1:
                self.file.rename(f'{self.name}-{ct:05}.safetensors')
                self.file.set_metadata(index = str(ct))
                self.files = {self.file.filename:self.file}
            self.file.finalize()
            self.total_size += self.file.size
            ct += 1
            self.file = self.File(f'{self.name}-{ct:05}.safetensors', index = ct)
            self.files[self.file.filename] = self.file
            self.file.add(name, tensor)
            assert name in self.file.header
    def finalize(self):
        self.file.finalize()
        if len(self.files) > 1:
            self.total_size += self.file.size
            index_name = self.name + '.safetensors.index.json'
            print(index_name, '...')
            tot = len(self.files)
            for ct, file in enumerate(self.files.values()):
                ct += 1
                file.rename(f'{self.name}-{ct:05}-of-{tot:06}.safetensors')
            with open(index_name, 'w') as fh:
                json.dump({
                    'metadata': {
                        **self.metadata,
                        'total_size': self.total_size,
                    },
                    'weight_map': {
                            name: file.filename
                            for name, file in self.weight_map.items()
                        }
                    },
                    indent = '\t',
                }, fh)
        del self.file
        del self.files
        del self.metadata
    def delete(self):
        for file in self.files.values():
            file.delete()
        del self.file
        del self.files
        del self.metadata
    def __enter__(self):
        return self
    def __exit__(self, Exc, exc, tb):
        throw = None
        if Exc is None:
            try:
                self.finalize()
            except:
                self.delete()
                raise
        else:
            self.delete()
        
    class File:
        def __init__(self, filename, **metadata):
            self.filename = filename
            self.fd = os.open(self.filename, os.O_RDWR | os.O_CREAT)
            self.size = 0
            self.capacity = 0
            self.mmapview = None
            self.header = {'__metadata__': {k:str(v) for k,v in metadata.items()}}
            self.finalized = False
        def _reserve(self, length):
            if self.size + length > self.capacity:
                new_capacity = self.size * 2
                if new_capacity < self.size + length:
                    new_capacity = (((self.size + length)*2 - 1) // mmap.PAGESIZE + 1) * mmap.PAGESIZE
                os.truncate(self.filename, new_capacity)
                self.mmapview = memoryview(mmap.mmap(self.fd, new_capacity))
                self.capacity = new_capacity
        def add(self, name, tensor):
            length = tensor.numel() * tensor.dtype.itemsize
            self._reserve(length)
            end = self.size + length
            torch.frombuffer(
                    self.mmapview[self.size:end],
                    dtype=tensor.dtype, count=tensor.numel(),
            ).view(tensor.shape)[:] = tensor
            self.header[name] = {
                'dtype': 
                    str(tensor.dtype).rsplit('.',1)[-1]
                        .replace('float','F')
                        .replace('uint','U')
                        .replace('int','I')
                        .removesuffix('fn')
                        .upper(),
                'shape':
                    list(tensor.shape),
                'data_offsets':
                    [self.size, end],
            }
            self.size = end
        def undo(self, name, tensor):
            length = tensor.numel() * tensor.dtype.itemsize
            del self.header[name]
            self.size -= length
        def set_metadata(self, **metadata):
            m = self.header['__metadata__']
            for k, v in metadata.items():
                m[k] = str(v)
        def rename(self, filename):
            os.rename(self.filename, filename)
            self.filename = filename
            return filename
        def finalize(self):
            print(self.filename, '...')
            header = json.dumps(self.header, separators=[',',':']).encode()
            insert = len(header) + 8
            self._reserve(insert)
            self.mmapview[insert:insert+self.size] = self.mmapview[:self.size]
            self.size += insert
            self.mmapview[:8] = len(header).to_bytes(8, 'little')
            self.mmapview[8:insert] = header
            del self.header
            del self.mmapview
            os.close(self.fd)
            os.truncate(self.filename, self.size)
            self.finalized = True
        def delete(self):
            if not self.finalized:
                print('deleting', self.filename, '...')
                del self.header
                del self.mmapview
                os.close(self.fd)
                self.finalized = True
            os.unlink(self.filename)