Update checkpointing to use fsspec

Summary:

- Make the data/checkpoint code fsspec compatible
- Still will not work with s3 saves, due to `torch.distributed.checkpoint.save` not being out of the box workable with `fsspec`. Will implement in followup PR


Test Plan:

Run unit tests and the commands below

```
python -m bytelatent.train config=internal/configs/s3_debug.yaml eval=null checkpoint.dump.every=100
```

```
torchrun --nproc-per-node 8 -m bytelatent.train config=internal/configs/s3_debug.yaml eval=null checkpoint.dump.every=100
```

These currently won't work due to the torch distributed save, but theses hould be tested at a later date

```
python -m bytelatent.train config=internal/configs/s3_debug.yaml eval=null checkpoint.dump.every=100 dump_dir=s3://blt/scratch/checkpoint-test/
```

```
torchrun --nproc-per-node 8 -m bytelatent.train config=internal/configs/s3_debug.yaml eval=null checkpoint.dump.every=100 dump_dir=s3://blt/scratch/checkpoint-test/
```

bytelatent/args.py

@@ -294,15 +294,19 @@ class TrainArgs(BaseModel):
     def dump_to_yaml_file(
         self, path: str, log_config: bool = True, sort_keys: bool = True
     ):
+        yaml_str = self.dump_to_yaml_str(sort_keys=sort_keys)
+        with open(path, "w") as f:
+            if log_config:
+                logger.info("Using the following config for this run:")
+                logger.info(yaml_str)
+            f.write(yaml_str)
+
+    def dump_to_yaml_str(self, sort_keys: bool = True):
         model_dict = self.model_dump(mode="json")
         yaml_str = yaml.dump(
             model_dict,
             allow_unicode=True,
             sort_keys=sort_keys,
             default_flow_style=False,
         )
-        with open(path, "w") as f:
-            if log_config:
-                logger.info("Using the following config for this run:")
-                logger.info(yaml_str)
-            f.write(yaml_str)
+        return yaml_str

bytelatent/checkpoint.py

@@ -4,10 +4,9 @@
 import logging
 import os
 import re
-from pathlib import Path
-from typing import List, Optional, Tuple
 
 import fsspec
+import s3fs
 import torch
 import torch.distributed as dist
 import torch.distributed.checkpoint as dcp
@@ -70,26 +69,29 @@ def consolidate_checkpoints(fs: fsspec.AbstractFileSystem, ckpt_dir: str):
 
     Returns the path to the consolidated checkpoint
     """
-    consolidate_path = Path(ckpt_dir) / CONSOLIDATE_FOLDER
-    if not (consolidate_path / CONSOLIDATE_NAME).exists():
-        consolidate_path.mkdir(exist_ok=True)
-        logger.info(f"Consolidating to: {str(consolidate_path)}")
-        dcp_to_torch_save(ckpt_dir, str(consolidate_path / CONSOLIDATE_NAME))
-        (consolidate_path / CONFIG_NAME).write_text(
-            (Path(ckpt_dir) / CONFIG_NAME).read_text()
+    consolidate_path = os.path.join(ckpt_dir, CONSOLIDATE_FOLDER)
+    consolidate_name = os.path.join(consolidate_path, CONSOLIDATE_NAME)
+    if not fs.exists(consolidate_name):
+        fs.mkdirs(consolidate_path, exist_ok=True)
+        logger.info(f"Consolidating to: {consolidate_path}")
+        dcp_to_torch_save(ckpt_dir, consolidate_name)
+        fs.write_text(
+            os.path.join(consolidate_path, CONFIG_NAME),
+            fs.read_text(os.path.join(ckpt_dir, CONFIG_NAME)),
         )
         logger.info("Consolidated !")
     return consolidate_path
 
 
 def load_from_checkpoint(
+    fs: fsspec.AbstractFileSystem,
     ckpt_dir: str,
     model: nn.Module,
-    optimizer: Optional[torch.optim.Optimizer] = None,
+    optimizer: torch.optim.Optimizer | None = None,
     model_key: str = "model",
     optim_key: str = "optim",
 ):
-    if not (Path(ckpt_dir) / ".metadata").exists():
+    if not fs.exists(os.path.join(ckpt_dir, ".metadata")):
         raise ValueError(
             f"Please convert the checkpoint distcp format using `torch.distributed.checkpoint.format_utils.torch_save_to_dcp` before loading it"
         )
@@ -115,19 +117,24 @@ def __init__(self, args: CheckpointArgs):
         self.init_ckpt_path = args.init_ckpt_path
         self.continue_training_from_init = args.continue_training_from_init
 
-        assert self.fs.exists(
-            self.path
-        ), f"Path {self.path} does not exist and needs to be created before using CheckpointManager (use instantiate_and_make_dir)"
+        if not isinstance(self.fs, s3fs.S3FileSystem):
+            # S3 does not have a concept of directories
+            assert self.fs.exists(
+                self.path
+            ), f"Path {self.path} does not exist and needs to be created before using CheckpointManager (use instantiate_and_make_dir)"
 
         self.existing_saves = self.get_existing_saves()
 
-    def get_existing_saves(self) -> List[Path]:
-        folders = [
-            p
-            for p in Path(self.path).iterdir()
-            if p.is_dir() and re.match(RE_FOLDER, p.name)
-        ]
-        folders.sort(key=lambda p: _get_key_step(p.name))
+    def get_existing_saves(self) -> list[str]:
+        if self.fs.exists(self.path) and self.fs.isdir(self.path):
+            folders = [
+                p
+                for p in self.fs.ls(self.path)
+                if self.fs.isdir(p) and re.match(RE_FOLDER, os.path.basename(p))
+            ]
+        else:
+            folders = []
+        folders.sort(key=lambda p: _get_key_step(os.path.basename(p)))
         return folders
 
     def clean_up(self):
@@ -136,8 +143,9 @@ def clean_up(self):
         eval_folders = []
         other_folders = []
         for p in self.existing_saves:
-            is_dump = _get_key_step(p.name) % self.dump_every.every == 0
-            is_eval = _get_key_step(p.name) % self.eval_every.every == 0
+            assert isinstance(p, str), f"Base path type: {p}"
+            is_dump = _get_key_step(os.path.basename(p)) % self.dump_every.every == 0
+            is_eval = _get_key_step(os.path.basename(p)) % self.eval_every.every == 0
             if is_dump:
                 dump_folders.append(p)
             if is_eval:
@@ -161,40 +169,39 @@ def clean_up(self):
 
         if dist.get_rank() == 0:
             for folder in folder_to_remove:
-                for file in folder.iterdir():
-                    if file.is_file():
-                        file.unlink()
-                    elif file.is_dir():
-                        assert file.name in [CONSOLIDATE_FOLDER]
-                        for f in file.iterdir():
-                            f.unlink()
-                        file.rmdir()
-                folder.rmdir()
+                for file in self.fs.ls(folder):
+                    if self.fs.isfile(file):
+                        self.fs.rm_file(file)
+                    elif self.fs.isdir(file):
+                        assert os.path.name(file) in [CONSOLIDATE_FOLDER]
+                        for f in self.fs.ls(file):
+                            self.fs.rm(f)
+                        self.fs.rmdir(file)
+                self.fs.rmdir(folder)
 
         dist.barrier()
 
         self.existing_saves = list(folder_to_keep)
-        self.existing_saves.sort(key=lambda p: _get_key_step(p.name))
+        self.existing_saves.sort(key=lambda p: _get_key_step(os.path.basename(p)))
 
-    def get_last_step_path(self, dp_rank: int = 0) -> Optional[Path]:
+    def get_last_step_path(self, dp_rank: int = 0) -> str | None:
         path = None
         for p in reversed(self.existing_saves):
-            if (p / TRAIN_STATE_NAME.format(dp_rank)).is_file():
+
+            if self.fs.isfile(os.path.join(p, TRAIN_STATE_NAME.format(dp_rank))):
                 path = p
                 break
         return path
 
-    def _create_folder(self, base_path: Path, folder_name: str) -> Path:
-        folder = base_path / folder_name
+    def _create_folder(self, base_path: str, folder_name: str) -> str:
+        folder = os.path.join(base_path, folder_name)
         if get_is_master():
-            folder.mkdir(parents=False, exist_ok=True)
+            self.fs.mkdirs(folder, exist_ok=True)
         if dist.is_initialized():
             dist.barrier()
         return folder
 
-    def _get_dp_tp_mesh(
-        self, device_mesh: Optional[DeviceMesh] = None
-    ) -> Tuple[int, int]:
+    def _get_dp_tp_mesh(self, device_mesh: DeviceMesh | None = None) -> tuple[int, int]:
         dp_rank = 0
         tp_rank = 0
         if device_mesh is not None:
@@ -222,14 +229,14 @@ def save(
         model,
         optimizer,
         train_state,
-        config,
-        device_mesh: Optional[DeviceMesh] = None,
+        config: BaseModel,
+        device_mesh: DeviceMesh | None = None,
     ) -> bool:
 
         # When creating directory check if only rank0 or is there other solution
-        path = Path(self.path)
+        path = self.path
         curr_save_dir = self._create_folder(path, FOLDER_NAME.format(train_state.step))
-        logger.info(f"Saving to: {str(curr_save_dir)}")
+        logger.info(f"Saving to: {curr_save_dir}")
 
         if dist.is_initialized():
             dist.barrier()
@@ -242,17 +249,19 @@ def save(
         if dist.is_initialized():
             dist.barrier()
 
+        print("config type", type(config))
         if get_is_master():
-            config.dump_to_yaml_file(curr_save_dir / CONFIG_NAME)
+            self.fs.write_text(
+                os.path.join(curr_save_dir, CONFIG_NAME), config.model_dump_json()
+            )
 
         # Add json dump here
         dp_rank, tp_rank = self._get_dp_tp_mesh(device_mesh)
         if tp_rank == 0:
             train_state_name = TRAIN_STATE_NAME.format(dp_rank)
-            logger.info(
-                f"Saving train state to: {str(curr_save_dir / train_state_name)}"
-            )
-            with open(curr_save_dir / train_state_name, "w") as f:
+            train_state_full_path = os.path.join(curr_save_dir, train_state_name)
+            logger.info(f"Saving train state to: {train_state_full_path}")
+            with self.fs.open(train_state_full_path, "w") as f:
                 json.dump(train_state.state_dict(), f)
             logger.info("Train state saved !")
 
@@ -271,7 +280,7 @@ def load(
         optimizer,
         train_state,
         device_mesh: DeviceMesh,
-        path: Optional[Path] = None,
+        path: str | None = None,
     ):
         dp_rank, tp_rank = self._get_dp_tp_mesh(device_mesh)
         # Loading tries to load the provided path, if not available the last saved step and finally from the init path
@@ -284,12 +293,12 @@ def load(
         # Only load train state if it's provided, the files exist and we're not loading from init path
         train_state_name = TRAIN_STATE_NAME.format(dp_rank)
         logger.info("Reloading train state")
-        with open(path / train_state_name, "r") as f:
+        with self.fs.open(os.path.join(path, train_state_name), "r") as f:
             train_state_dict = json.load(f)
         train_state.load_state_dict(train_state_dict)
         logger.info("Train state reloaded")
 
-        logger.info(f"Loading from: {str(path)}")
+        logger.info(f"Loading from: {path}")
         state_dict = self.get_state_dict(
             model=model,
             optimizer=optimizer,

bytelatent/logger.py

@@ -6,6 +6,8 @@
 import time
 from datetime import timedelta
 
+import fsspec
+
 from bytelatent.distributed import get_global_rank, get_is_slurm_job
 
 
@@ -92,6 +94,7 @@ def init_logger(
     *,
     name: str | None = None,
     level: str = "INFO",
+    fs: fsspec.AbstractFileSystem | None = None,
 ):
     """
     Setup logging.
@@ -121,7 +124,11 @@ def init_logger(
 
     if log_file is not None and get_global_rank() == 0:
         # build file handler
-        file_handler = logging.FileHandler(log_file, "a")
+        if fs is None:
+            file_handler = logging.FileHandler(log_file, "a")
+        else:
+            file_stream = fs.open(log_file, mode="a")
+            file_handler = logging.StreamHandler(file_stream)
         file_handler.setLevel(logging.NOTSET)
         file_handler.setFormatter(LogFormatter())
         # update logger

bytelatent/metrics.py

@@ -9,6 +9,7 @@
 from pathlib import Path
 from typing import Any, Union
 
+import fsspec
 import torch
 import torch.nn as nn
 import wandb
@@ -54,14 +55,24 @@ class LoggingArgs(BaseModel):
 
 
 class MetricLogger:
-    def __init__(self, outdir: Path, args: Any | None = None):
+    def __init__(
+        self,
+        outdir: Path,
+        # args: TrainArgs
+        args: Any | None = None,
+        fs: fsspec.AbstractFileSystem | None = None,
+    ):
         self.outdir = outdir
         self.jsonl_writer = None
+        self.fs = fs
         self.args = args
 
     def open(self):
         if self.jsonl_writer is None:
-            self.jsonl_writer = open(self.outdir, "a")
+            if self.fs is None:
+                self.jsonl_writer = open(self.outdir, "a")
+            else:
+                self.jsonl_writer = self.fs.open(self.outdir, "a")
         if (
             self.args is not None
             and self.args.logging.wandb is not None