try allow parallel requests

lib/backend.py

@@ -9,7 +9,6 @@ from asyncio import wait, sleep, gather, Semaphore, FIRST_COMPLETED, create_task
 from typing import Tuple, Awaitable, NoReturn, List, Union, Callable, Optional
 from functools import cached_property
 from distutils.util import strtobool
-from collections import deque
 
 from anyio import open_file
 from aiohttp import web, ClientResponse, ClientSession, ClientConnectorError, ClientTimeout, TCPConnector
@@ -31,7 +30,7 @@ from lib.data_types import (
     BenchmarkResult
 )
 
-VERSION = "0.2.1"
+VERSION = "0.2.0"
 
 MSG_HISTORY_LEN = 100
 log = logging.getLogger(__file__)
@@ -64,7 +63,6 @@ class Backend:
     version = VERSION
     msg_history = []
     sem: Semaphore = dataclasses.field(default_factory=Semaphore)
-    queue: deque = dataclasses.field(default_factory=deque, repr=False)
     unsecured: bool = dataclasses.field(
         default_factory=lambda: bool(strtobool(os.environ.get("UNSECURED", "false"))),
     )
@@ -143,26 +141,11 @@ class Backend:
         workload = payload.count_workload()
         request_metrics: RequestMetrics = RequestMetrics(request_idx=auth_data.request_idx, reqnum=auth_data.reqnum, workload=workload, status="Created")
 
-
+        async def cancel_api_call_if_disconnected() -> web.Response:
-        def advance_queue_after_completion(event: asyncio.Event):
-            """Pop current head and wake next waiter, if any."""
-            # If this event is current head, wake next waiter
-            if self.queue and self.queue[0] is event:
-                self.queue.popleft()
-                if self.queue:
-                    self.queue[0].set()
-            else:
-                # Else, remove it from the queue
-                try:
-                    self.queue.remove(event)
-                except ValueError:
-                    pass
-
-        async def cancel_api_call_if_disconnected() -> None:
             await request.wait_for_disconnection()
-            log.debug(f"Request with reqnum: {request_metrics.reqnum} was canceled")
+            log.debug(f"request with reqnum: {request_metrics.reqnum} was canceled")
             self.metrics._request_canceled(request_metrics)
-            return
+            raise asyncio.CancelledError
 
         async def make_request() -> Union[web.Response, web.StreamResponse]:
             try:
@@ -179,9 +162,7 @@ class Backend:
                 res = await handler.generate_client_response(request, response)
                 self.metrics._request_success(request_metrics)
                 return res
-            except asyncio.CancelledError:
+            except requests.exceptions.RequestException as e:
-                raise
-            except Exception as e:
                 log.debug(f"[backend] Request error: {e}")
                 self.metrics._request_errored(request_metrics)
                 return web.Response(status=500)
@@ -196,87 +177,46 @@ class Backend:
             self.metrics._request_reject(request_metrics)
             return web.Response(status=429)
 
-        disconnect_task = create_task(cancel_api_call_if_disconnected())
+        acquired = False
-        next_request_task = None
-        work_task = None
-        event = asyncio.Event() # Used in finally block, so initialize here
-
-        self.metrics._request_start(request_metrics)
-
         try:
-            if self.allow_parallel_requests:
+            self.metrics._request_start(request_metrics)
-                log.debug(f"Starting request for reqnum:{request_metrics.reqnum}")
+            if self.allow_parallel_requests is False:
-                work_task = create_task(make_request())
+                log.debug(f"Waiting to aquire Sem for reqnum:{request_metrics.reqnum}")
-                done, pending = await wait([work_task, disconnect_task], return_when=FIRST_COMPLETED)
+                await self.sem.acquire()
-
+                acquired = True
-                for t in pending:
+                log.debug(
-                    t.cancel()
+                    f"Sem acquired for reqnum:{request_metrics.reqnum}, starting request..."
-                await asyncio.gather(*pending, return_exceptions=True)
-
-                if disconnect_task in done:
-                    return web.Response(status=499)
-
-                # otherwise work_task completed
-                return await work_task
-            
-            # FIFO-queue branch
-            else:
-                # Insert a Event into the queue for this request
-                # Event.set() == our request is up next
-                self.queue.append(event)
-                if self.queue and self.queue[0] is event:
-                    event.set()
-
-                # Race between our request being next and request being cancelled
-                next_request_task = create_task(event.wait())
-                first_done, first_pending = await wait(
-                    [next_request_task, disconnect_task], return_when=FIRST_COMPLETED
                 )
+            else:
+                log.debug(f"Starting request for reqnum:{request_metrics.reqnum}")
+            done, pending = await wait(
+                [
+                    create_task(make_request()),
+                    create_task(cancel_api_call_if_disconnected()),
+                ],
+                return_when=FIRST_COMPLETED,
+            )
+            for t in pending:
+                t.cancel()
+            await asyncio.gather(*pending, return_exceptions=True)
 
-                # If the disconnect task wins the race
+            done_task = done.pop()
-                if disconnect_task in first_done:
+            try:
-                    # Clean up the next_request_task, then exit
+                return done_task.result()
-                    for t in first_pending:
+            except Exception as e:
-                        t.cancel()
+                log.debug(f"Request task raised exception: {e}")
-                    await asyncio.gather(*first_pending, return_exceptions=True)
+                return web.Response(status=500)
-                    return web.Response(status=499)
-
-                # We are the next-up request in the queue
-                log.debug(f"Starting work on request {request_metrics.reqnum}...")
-
-                # Race the backend API call with the disconnect task
-                work_task = create_task(make_request())
-
-                done, pending = await wait([work_task, disconnect_task], return_when=FIRST_COMPLETED)
-                for t in pending:
-                    t.cancel()
-                await asyncio.gather(*pending, return_exceptions=True)
-
-                if disconnect_task in done:
-                    return web.Response(status=499)
-
-                # otherwise work_task completed
-                return await work_task
-            
         except asyncio.CancelledError:
-            return web.Response(status=499)
+            # Client is gone. Do not write a response; just unwind.
-        
+            return web.Response(status=499) 
         except Exception as e:
             log.debug(f"Exception in main handler loop {e}")
             return web.Response(status=500)
-        
         finally:
-            if not self.allow_parallel_requests:
+            # Always release the semaphore if it was acquired
-                advance_queue_after_completion(event)
+            if acquired:
-
+                self.sem.release()
             self.metrics._request_end(request_metrics)
-            cleanup_tasks = [t for t in (next_request_task, work_task, disconnect_task) if t]
-            for t in cleanup_tasks:
-                if not t.done():
-                    t.cancel()
-            if cleanup_tasks:
-                await asyncio.gather(*cleanup_tasks, return_exceptions=True)
-
 
     @cached_property  
     def healthcheck_session(self):

workers/comfyui-json/server.py

@@ -89,7 +89,7 @@ class ComfyWorkflowHandler(EndpointHandler[ComfyWorkflowData]):
 backend = Backend(
     model_server_url=MODEL_SERVER_URL,
     model_log_file=os.environ["MODEL_LOG"],
-    allow_parallel_requests=False,
+    allow_parallel_requests=True,
     benchmark_handler=ComfyWorkflowHandler(
         benchmark_runs=3, benchmark_words=100
     ),