fix for logging server serialization problems

Author: apoorvkh

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "torchrunx"
-version = "0.2.0"
+version = "0.2.1"
 authors = [
     {name = "Apoorv Khandelwal", email = "[email protected]"},
     {name = "Peter Curtin", email = "[email protected]"},

src/torchrunx/launcher.py

@@ -16,7 +16,7 @@
 from dataclasses import dataclass
 from functools import partial, reduce
 from logging import Handler
-from multiprocessing import Process
+from multiprocessing import Event, Process
 from operator import add
 from pathlib import Path
 from typing import Any, Callable, Literal
@@ -34,7 +34,7 @@
     ExceptionFromWorker,
     WorkerFailedError,
 )
-from .utils.logging import LogRecordSocketReceiver, default_handlers
+from .utils.logging import LoggingServerArgs, start_logging_server
 
 
 @dataclass
@@ -76,27 +76,32 @@ def run(  # noqa: C901, PLR0912
 
         launcher_hostname = socket.getfqdn()
         launcher_port = get_open_port()
+        logging_port = get_open_port()
         world_size = len(hostnames) + 1
 
-        log_receiver = None
+        stop_logging_event = None
         log_process = None
         launcher_agent_group = None
         agent_payloads = None
 
         try:
             # Start logging server (recieves LogRecords from agents/workers)
 
-            log_receiver = _build_logging_server(
+            logging_server_args = LoggingServerArgs(
                 log_handlers=log_handlers,
-                launcher_hostname=launcher_hostname,
+                logging_hostname=launcher_hostname,
+                logging_port=logging_port,
                 hostnames=hostnames,
                 workers_per_host=workers_per_host,
                 log_dir=Path(os.environ.get("TORCHRUNX_LOG_DIR", "torchrunx_logs")),
                 log_level=logging._nameToLevel[os.environ.get("TORCHRUNX_LOG_LEVEL", "INFO")],  # noqa: SLF001
             )
 
+            stop_logging_event = Event()
+
             log_process = Process(
-                target=log_receiver.serve_forever,
+                target=start_logging_server,
+                args=(logging_server_args.serialize(), stop_logging_event),
                 daemon=True,
             )
 
@@ -109,7 +114,7 @@ def run(  # noqa: C901, PLR0912
                     command=_build_launch_command(
                         launcher_hostname=launcher_hostname,
                         launcher_port=launcher_port,
-                        logger_port=log_receiver.port,
+                        logger_port=logging_port,
                         world_size=world_size,
                         rank=i + 1,
                         env_vars=(self.default_env_vars + self.extra_env_vars),
@@ -166,11 +171,10 @@ def run(  # noqa: C901, PLR0912
                 if all(s.state == "done" for s in agent_statuses):
                     break
         finally:
-            if log_receiver is not None:
-                log_receiver.shutdown()
-                if log_process is not None:
-                    log_receiver.server_close()
-                    log_process.kill()
+            if stop_logging_event is not None:
+                stop_logging_event.set()
+            if log_process is not None:
+                log_process.kill()
 
             if launcher_agent_group is not None:
                 launcher_agent_group.shutdown()
@@ -307,31 +311,6 @@ def _resolve_workers_per_host(
     return workers_per_host
 
 
-def _build_logging_server(
-    log_handlers: list[Handler] | Literal["auto"] | None,
-    launcher_hostname: str,
-    hostnames: list[str],
-    workers_per_host: list[int],
-    log_dir: str | os.PathLike,
-    log_level: int,
-) -> LogRecordSocketReceiver:
-    if log_handlers is None:
-        log_handlers = []
-    elif log_handlers == "auto":
-        log_handlers = default_handlers(
-            hostnames=hostnames,
-            workers_per_host=workers_per_host,
-            log_dir=log_dir,
-            log_level=log_level,
-        )
-
-    return LogRecordSocketReceiver(
-        host=launcher_hostname,
-        port=get_open_port(),
-        handlers=log_handlers,
-    )
-
-
 def _build_launch_command(
     launcher_hostname: str,
     launcher_port: int,

src/torchrunx/utils/logging.py

@@ -3,7 +3,8 @@
 from __future__ import annotations
 
 __all__ = [
-    "LogRecordSocketReceiver",
+    "LoggingServerArgs",
+    "start_logging_server",
     "redirect_stdio_to_logger",
     "log_records_to_socket",
     "add_filter_to_handler",
@@ -25,12 +26,14 @@
 from logging.handlers import SocketHandler
 from pathlib import Path
 from socketserver import StreamRequestHandler, ThreadingTCPServer
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Literal
 
+import cloudpickle
 from typing_extensions import Self
 
 if TYPE_CHECKING:
     import os
+    from multiprocessing.synchronize import Event as EventClass
 
 ## Handler utilities
 
@@ -139,7 +142,7 @@ def default_handlers(
 ## Launcher utilities
 
 
-class LogRecordSocketReceiver(ThreadingTCPServer):
+class _LogRecordSocketReceiver(ThreadingTCPServer):
     """TCP server for recieving Agent/Worker log records in Launcher.
 
     Uses threading to avoid bottlenecks (i.e. "out-of-order" logs in Launcher process).
@@ -180,6 +183,60 @@ def shutdown(self) -> None:
         self._BaseServer__is_shut_down.wait(timeout=3)  # pyright: ignore[reportAttributeAccessIssue]
 
 
+@dataclass
+class LoggingServerArgs:
+    log_handlers: list[Handler] | Literal["auto"] | None
+    logging_hostname: str
+    logging_port: int
+    hostnames: list[str]
+    workers_per_host: list[int]
+    log_dir: str | os.PathLike
+    log_level: int
+
+    def serialize(self) -> SerializedLoggingServerArgs:
+        return SerializedLoggingServerArgs(args=self)
+
+
+class SerializedLoggingServerArgs:
+    def __init__(self, args: LoggingServerArgs) -> None:
+        self.bytes = cloudpickle.dumps(args)
+
+    def deserialize(self) -> LoggingServerArgs:
+        return cloudpickle.loads(self.bytes)
+
+
+def start_logging_server(
+    serialized_args: SerializedLoggingServerArgs,
+    stop_event: EventClass,
+) -> None:
+    args: LoggingServerArgs = serialized_args.deserialize()
+
+    log_handlers = args.log_handlers
+    if log_handlers is None:
+        log_handlers = []
+    elif log_handlers == "auto":
+        log_handlers = default_handlers(
+            hostnames=args.hostnames,
+            workers_per_host=args.workers_per_host,
+            log_dir=args.log_dir,
+            log_level=args.log_level,
+        )
+
+    log_receiver = _LogRecordSocketReceiver(
+        host=args.logging_hostname,
+        port=args.logging_port,
+        handlers=log_handlers,
+    )
+
+    log_receiver.serve_forever()
+
+    while not stop_event.is_set():
+        pass
+
+    log_receiver.shutdown()
+    log_receiver.server_close()
+
+
 ## Agent/worker utilities