trying queue

vLLM Prefix caching, benchmark bug fix, test load script

lib/backend.py

@@ -5,7 +5,7 @@ import base64
 import subprocess
 import dataclasses
 import logging
-from asyncio import wait, sleep, gather, Semaphore, FIRST_COMPLETED, create_task
+from asyncio import wait, sleep, gather, Semaphore, FIRST_COMPLETED, create_task, get_running_loop
 from typing import Tuple, Awaitable, NoReturn, List, Union, Callable, Optional
 from functools import cached_property
 from distutils.util import strtobool
@@ -47,7 +47,7 @@ class Backend:
     This class is responsible for:
     1. Tailing logs and updating load time metrics
     2. Taking an EndpointHandler alongside incoming payload, preparing a json to be sent to the model, and
-    sending the request. It also updates metrics as it makes those requests.
+       sending the request. It also updates metrics as it makes those requests.
     3. Running a benchmark from an EndpointHandler
     """
 
@@ -74,6 +74,11 @@ class Backend:
         self._pubkey = self._fetch_pubkey()
         self.__start_healthcheck: bool = False
 
+        # NEW: FIFO queue + worker count
+        self.request_queue: "asyncio.Queue[tuple[EndpointHandler[ApiPayload_T], web.Request, asyncio.Future]]" = asyncio.Queue()
+        # If parallel allowed, let multiple workers drain the queue (order preserved by FIFO per worker; overall start order is FIFO).
+        self._num_workers: int = 1 if not self.allow_parallel_requests else int(os.environ.get("WORKERS", "4"))
+
     @property
     def pubkey(self) -> Optional[RSA.RsaKey]:
         if self._pubkey is None:
@@ -91,6 +96,22 @@ class Backend:
         timeout = ClientTimeout(total=None)
         return ClientSession(self.model_server_url, timeout=timeout, connector=connector)
 
+    async def _worker(self):
+        while True:
+            handler, request, fut = await self.request_queue.get()
+            try:
+                # Skip if already cancelled while waiting in the queue
+                if fut.cancelled():
+                    continue
+                res = await self.__process_enqueued_request(handler, request)
+                if not fut.cancelled():
+                    fut.set_result(res)
+            except Exception as e:
+                if not fut.cancelled():
+                    fut.set_exception(e)
+            finally:
+                self.request_queue.task_done()
+
     def create_handler(
         self,
         handler: EndpointHandler[ApiPayload_T],
@@ -127,7 +148,36 @@ class Backend:
         handler: EndpointHandler[ApiPayload_T],
         request: web.Request,
     ) -> Union[web.Response, web.StreamResponse]:
-        """use this function to forward requests to the model endpoint"""
+        """use this function to enqueue requests for FIFO processing"""
+        loop = get_running_loop()
+        fut: asyncio.Future = loop.create_future()
+
+        # If the client disconnects while waiting in the FIFO, cancel the future so the worker skips it
+        cancel_watch = create_task(request.wait_for_disconnection())
+        def _cancel_if_disconnected(_):
+            if not fut.done():
+                fut.cancel()
+        cancel_watch.add_done_callback(_cancel_if_disconnected)
+
+        try:
+            await self.request_queue.put((handler, request, fut))
+            return await fut
+        except asyncio.CancelledError:
+            # Propagate cancellation to ensure aiohttp doesn't expect a response body
+            raise
+        finally:
+            # Best-effort cleanup of the watcher
+            cancel_watch.cancel()
+
+    async def __process_enqueued_request(
+        self,
+        handler: EndpointHandler[ApiPayload_T],
+        request: web.Request,
+    ) -> Union[web.Response, web.StreamResponse]:
+        """
+        This contains the original __handle_request logic and is invoked by workers,
+        ensuring FIFO execution via asyncio.Queue.
+        """
         try:
             data = await request.json()
             auth_data, payload = handler.get_data_from_request(data)
@@ -135,8 +185,11 @@ class Backend:
             return web.json_response(data=e.message, status=422)
         except json.JSONDecodeError:
             return web.json_response(dict(error="invalid JSON"), status=422)
+
         workload = payload.count_workload()
-        request_metrics: RequestMetrics = RequestMetrics(request_idx=auth_data.request_idx, reqnum=auth_data.reqnum, workload=workload, status="Created")
+        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:
             await request.wait_for_disconnection()
@@ -177,6 +230,8 @@ class Backend:
         acquired = False
         try:
             self.metrics._request_start(request_metrics)
+
+            # Preserve existing semaphore behavior for serializing requests when requested
             if self.allow_parallel_requests is False:
                 log.debug(f"Waiting to aquire Sem for reqnum:{request_metrics.reqnum}")
                 await self.sem.acquire()
@@ -186,6 +241,7 @@ class Backend:
                 )
             else:
                 log.debug(f"Starting request for reqnum:{request_metrics.reqnum}")
+
             done, pending = await wait(
                 [
                     create_task(make_request()),
@@ -253,8 +309,14 @@ class Backend:
                 self.backend_errored(str(e))
 
     async def _start_tracking(self) -> None:
+        # Start the FIFO workers alongside existing loops
+        worker_tasks = tuple(self._worker() for _ in range(self._num_workers))
         await gather(
-            self.__read_logs(), self.metrics._send_metrics_loop(), self.__healthcheck(), self.metrics._send_delete_requests_loop()
+            self.__read_logs(),
+            self.metrics._send_metrics_loop(),
+            self.__healthcheck(),
+            self.metrics._send_delete_requests_loop(),
+            *worker_tasks,
         )
 
     def backend_errored(self, msg: str) -> None:
@@ -350,6 +412,9 @@ class Backend:
                 total_workload = sum(br.workload for br in benchmark_requests if br.is_successful)
                 time_elapsed = time.time() - start
                 successful_responses = sum([1 for br in benchmark_requests if br.is_successful])
+                if successful_responses == 0:
+                    self.backend_errored("No successful responses from benchmark")
+                    log.debug(f"benchmark failed: {successful_responses}/{concurrent_requests} successful responses")
 
                 throughput = total_workload / time_elapsed
                 sum_throughput += throughput

lib/data_types.py

@@ -257,7 +257,7 @@ class ModelMetrics:
     def wait_time(self) -> float:
         if (len(self.requests_working) == 0):
             return 0.0
-        return sum([request.workload for request in self.requests_working.values()]) / self.max_throughput
+        return sum([request.workload for request in self.requests_working.values()]) / max(self.max_throughput, 0.00001)
     
     @property
     def cur_load(self) -> float:

lib/metrics.py

@@ -145,14 +145,15 @@ class Metrics:
     #######################################Private#######################################
 
     async def __send_delete_requests_and_reset(self):
-
+        async def post(report_addr: str, idxs: list[int], success_flag: bool) -> bool:
-        async def send_data(report_addr: str, success: bool) -> bool:
             data = {
                 "worker_id": self.id,
-                "request_idxs": [r.request_idx for r in self.model_metrics.requests_deleting if r.success == success],
+                "request_idxs": idxs,
-                "success": success
+                "success": success_flag,
             }
-            log.debug(f"Deleting requests that {'succeeded' if success else 'failed'}: {data['request_idxs']}")
+            log.debug(
+                f"Deleting requests that {'succeeded' if success_flag else 'failed'}: {data['request_idxs']}"
+            )
             full_path = report_addr.rstrip("/") + "/delete_requests/"
             for attempt in range(1, 4):
                 try:
@@ -162,16 +163,38 @@ class Metrics:
                         res.raise_for_status()
                     return True
                 except asyncio.TimeoutError:
-                    log.debug(f"delete_requests timed out")
+                    log.debug("delete_requests timed out")
                 except (ClientResponseError, Exception) as e:
                     log.debug(f"delete_requests failed with error: {e}")
                 await asyncio.sleep(2)
                 log.debug(f"retrying delete_request, attempt: {attempt}")
+            return False
+
+        # Take a snapshot of what we plan to send this tick.
+        # New arrivals after this snapshot will remain in the queue for the next tick.
+        snapshot = list(self.model_metrics.requests_deleting)
+        success_idxs = [r.request_idx for r in snapshot if r.success is True]
+        failed_idxs  = [r.request_idx for r in snapshot if r.success is False]
+
+        if not success_idxs and not failed_idxs:
+            return  # nothing to do
 
         for report_addr in self.report_addr:
-            success = await send_data(report_addr, success=True) and await send_data(report_addr, success=False)
+            sent_success = True
-            if success is True:
+            sent_failed  = True
-                self.model_metrics.requests_deleting.clear()
+
+            if success_idxs:
+                sent_success = await post(report_addr, success_idxs, True)
+            if failed_idxs:
+                sent_failed = await post(report_addr, failed_idxs, False)
+
+            if sent_success and sent_failed:
+                # Remove only the items we actually sent from the live queue.
+                sent_set = set(success_idxs) | set(failed_idxs)
+                self.model_metrics.requests_deleting[:] = [
+                    r for r in self.model_metrics.requests_deleting
+                    if r.request_idx not in sent_set
+                ]
                 break
 
 

workers/comfyui-json/README.md

@@ -12,9 +12,21 @@ A docker image is provided but you may use any if the above requirements are met
 
 ## Benchmarking
 
-A simple image generation benchmark runs when each worker initializes to validate GPU performance and identify underperforming machines.
+### Custom Benchmark Workflows
 
-The benchmark uses Stable Diffusion v1.5 with ComfyUI's default text-to-image workflow. Configure the benchmark complexity and duration using these variables:
+You can provide a custom ComfyUI workflow for benchmarking by creating `workers/comfyui-json/misc/benchmark.json`. This allows you to test performance using your preferred models and workflow complexity.
+
+**Ways to provide the benchmark file:**
+- Fork this repository and add your `benchmark.json` file
+- Write the file during worker provisioning (onstart script or setup phase)
+
+An example file is provided in the repository. To ensure varied generations, use the placeholder `__RANDOM_INT__` in place of static seed values - it will be replaced with a random integer for each benchmark run.
+
+### Default Benchmark (Fallback)
+
+If `benchmark.json` is not available, a simple image generation benchmark runs when each worker initializes. This validates GPU performance and helps identify underperforming machines.
+
+The default benchmark uses Stable Diffusion v1.5 with ComfyUI's standard text-to-image workflow. Configure it using these environment variables:
 
 | Environment Variable | Default Value | Description |
 | -------------------- | ------------- | ----------- |
@@ -24,7 +36,7 @@ The benchmark uses Stable Diffusion v1.5 with ComfyUI's default text-to-image wo
 
 Each benchmark run uses a random prompt from `misc/test_prompts.txt` and a random seed to ensure consistent GPU load patterns.
 
-### Calibrating Benchmark Duration
+#### Calibrating Fallback Benchmark Duration
 
 To screen for underperforming hardware, set `BENCHMARK_TEST_STEPS` to match your expected production workflow duration. This allows you to identify machines that won't meet performance requirements.
 

workers/comfyui-json/data_types.py

@@ -5,12 +5,13 @@ import dataclasses
 from typing import Dict, Any
 from functools import cache
 from math import ceil
+from pathlib import Path
+import json
+import logging
 
 from lib.data_types import ApiPayload, JsonDataException
 
-
+log = logging.getLogger(__file__)
-with open("workers/comfyui/misc/test_prompts.txt", "r") as f:
-    test_prompts = f.readlines()
 
 def count_workload() -> float:
     # Always 100.0 where there is a single instance of ComfyUI handling requests
@@ -24,9 +25,32 @@ class ComfyWorkflowData(ApiPayload):
     @classmethod
     def for_test(cls):
         """
-        Use the variables available to simulate workflows of the required running time
+        If the user has provided a benchmark workflow we can use it here to properly gauge performance.
+        Otherwise, use the variables available to simulate workflows of the required running time
         Example: SD1.5, simple image gen 10000 steps, 512px x 512px will run for approximately 9 minutes @ ~18 it/s (RTX 4090)
         """
+        # Try to load benchmark.json
+        benchmark_file = Path("workers/comfyui-json/misc/benchmark.json")
+        
+        if benchmark_file.exists():
+            try:
+                with open(benchmark_file, "r") as f:
+                    benchmark_workflow = json.load(f)
+                return cls(
+                    input={
+                        "request_id": f"test-{random.randint(1000, 99999)}",
+                        "workflow_json": benchmark_workflow
+                    }
+                )
+            except (json.JSONDecodeError, IOError):
+                # JSON is malformed or file can't be read, fall through to default
+                log.error(f"Failed to benchmark using {benchmark_file}")
+        
+        # Fallback: read prompts and construct payload
+        log.info("Using fallback method for benchmarking")
+        with open("workers/comfyui-json/misc/test_prompts.txt", "r") as f:
+            test_prompts = f.readlines()
+        
         test_prompt = random.choice(test_prompts).rstrip()
         return cls(
             input={

workers/comfyui-json/misc/benchmark.json.example

@@ -0,0 +1,107 @@
+{
+    "3": {
+        "inputs": {
+            "seed": "__RANDOM_INT__",
+            "steps": 20,
+            "cfg": 8,
+            "sampler_name": "euler",
+            "scheduler": "normal",
+            "denoise": 1,
+            "model": [
+            "4",
+            0
+            ],
+            "positive": [
+            "6",
+            0
+            ],
+            "negative": [
+            "7",
+            0
+            ],
+            "latent_image": [
+            "5",
+            0
+            ]
+        },
+        "class_type": "KSampler",
+        "_meta": {
+            "title": "KSampler"
+        }
+    },
+    "4": {
+        "inputs": {
+            "ckpt_name": "v1-5-pruned-emaonly-fp16.safetensors"
+        },
+        "class_type": "CheckpointLoaderSimple",
+        "_meta": {
+            "title": "Load Checkpoint"
+        }
+    },
+    "5": {
+        "inputs": {
+            "width": 512,
+            "height": 512,
+            "batch_size": 1
+        },
+        "class_type": "EmptyLatentImage",
+        "_meta": {
+            "title": "Empty Latent Image"
+        }
+    },
+    "6": {
+        "inputs": {
+            "text": "beautiful scenery nature glass bottle landscape, , purple galaxy bottle,",
+            "clip": [
+            "4",
+            1
+            ]
+        },
+        "class_type": "CLIPTextEncode",
+        "_meta": {
+            "title": "CLIP Text Encode (Prompt)"
+        }
+    },
+    "7": {
+        "inputs": {
+            "text": "text, watermark",
+            "clip": [
+            "4",
+            1
+            ]
+        },
+        "class_type": "CLIPTextEncode",
+        "_meta": {
+            "title": "CLIP Text Encode (Prompt)"
+        }
+    },
+    "8": {
+        "inputs": {
+            "samples": [
+            "3",
+            0
+            ],
+            "vae": [
+            "4",
+            2
+            ]
+        },
+        "class_type": "VAEDecode",
+        "_meta": {
+            "title": "VAE Decode"
+        }
+    },
+    "9": {
+        "inputs": {
+            "filename_prefix": "ComfyUI",
+            "images": [
+            "8",
+            0
+            ]
+        },
+        "class_type": "SaveImage",
+        "_meta": {
+            "title": "Save Image"
+        }
+    }
+}

workers/comfyui-json/server.py

@@ -19,6 +19,7 @@ MODEL_SERVER_START_LOG_MSG = "To see the GUI go to: "
 MODEL_SERVER_ERROR_LOG_MSGS = [
     "MetadataIncompleteBuffer",  # This error is emitted when the downloaded model is corrupted
     "Value not in list: ",  # This error is emitted when the model file is not there at all
+    "[ERROR] Provisioning Script failed", # Error inserted by provisioning script if models/nodes fail to download
 ]