fix(api): track currently active worker for each device

api/onnx_web/worker/context.py

@@ -1,4 +1,5 @@
 from logging import getLogger
+from os import getpid
 from typing import Any, Callable, Tuple
 
 from torch.multiprocessing import Queue, Value
@@ -15,6 +16,7 @@ class WorkerContext:
     cancel: "Value[bool]"
     job: str
     pending: "Queue[Tuple[str, Callable[..., None], Any, Any]]"
+    current: "Value[int]"
     progress: "Queue[Tuple[str, str, int]]"
 
     def __init__(
@@ -26,6 +28,7 @@ def __init__(
         pending: "Queue[Tuple[str, Callable[..., None], Any, Any]]",
         progress: "Queue[Tuple[str, str, int]]",
         finished: "Queue[Tuple[str, str]]",
+        current: "Value[int]",
     ):
         self.job = job
         self.device = device
@@ -34,10 +37,17 @@ def __init__(
         self.finished = finished
         self.logs = logs
         self.pending = pending
+        self.current = current
 
     def is_cancelled(self) -> bool:
         return self.cancel.value
 
+    def is_current(self) -> bool:
+        if self.current.value > 0:
+            return self.current.value == getpid()
+
+        return True
+
     def get_device(self) -> DeviceParams:
         """
         Get the device assigned to this job.

api/onnx_web/worker/pool.py

@@ -23,6 +23,7 @@ class DevicePoolExecutor:
 
     leaking: List[Tuple[str, Process]]
     context: Dict[str, WorkerContext]  # Device -> Context
+    current: Dict[str, "Value[int]"]
     pending: Dict[str, "Queue[Tuple[str, Callable[..., None], Any, Any]]"]
     threads: Dict[str, Thread]
     workers: Dict[str, Process]
@@ -52,6 +53,7 @@ def __init__(
 
         self.leaking = []
         self.context = {}
+        self.current = {}
         self.pending = {}
         self.threads = {}
         self.workers = {}
@@ -85,6 +87,14 @@ def create_device_worker(self, device: DeviceParams) -> None:
             pending = Queue(self.max_pending_per_worker)
             self.pending[name] = pending
 
+        if name in self.current:
+            logger.debug("using existing current worker value")
+            current = self.current[name]
+        else:
+            logger.debug("creating new current worker value")
+            current = Value("L", 0)
+            self.current[name] = current
+
         context = WorkerContext(
             name,
             device,
@@ -93,16 +103,19 @@ def create_device_worker(self, device: DeviceParams) -> None:
             finished=self.finished,
             logs=self.logs,
             pending=pending,
+            current=current,
         )
         self.context[name] = context
-        self.workers[name] = Process(
+        worker = Process(
             name=f"onnx-web worker: {name}",
             target=worker_main,
             args=(context, self.server),
         )
 
         logger.debug("starting worker for device %s", device)
-        self.workers[name].start()
+        worker.start()
+        self.workers[name] = worker
+        current.value = worker.pid
 
     def create_logger_worker(self) -> None:
         def logger_worker(logs: Queue):

api/onnx_web/worker/worker.py

@@ -24,6 +24,10 @@ def worker_main(context: WorkerContext, server: ServerContext):
 
     while True:
         try:
+            if not context.is_current():
+                logger.warning("worker has been replaced, exiting")
+                exit(3)
+
             name, fn, args, kwargs = context.pending.get(timeout=1.0)
             logger.info("worker for %s got job: %s", context.device.device, name)