Proposing GPU booking constraints: Rolling window and advance booking limits

[chriskuipers]

Motivation

To ensure fair access to GPU resources and maximize their utilization, I'm proposing booking constraints that help distribute GPU availability across all users. These changes aim to:

• Promote fairness: Ensure all users have the opportunity to access GPU resources by preventing early and repeated bookings
• Encourage efficient utilization: Promote more intentionally booking GPUs, reducing idle time and wasted resources
• Improve availability: Distribute bookings more evenly so GPUs don't sit idle while others wait

Changes added

• Rolling window limit: Users can book a maximum of 7 days within any 4-week rolling period. This ensures you can still use GPUs regularly, but not continuously block them for weeks on end.
• Advance booking limit: Bookings can only be made up to 5 weeks in advance. This prevents people from locking up GPUs months ahead when they're not sure they'll actually need them.
• Both constraints include clear error messages that explain why a booking was rejected and how many days are still available.

[lwinckers]

Got the following error when deployed on test and trying to book a GPU.

INFO:     172.19.0.4:58062 - "OPTIONS /gpu/request HTTP/1.1" 200 OK
INFO:     172.19.0.4:58062 - "POST /gpu/request HTTP/1.1" 500 Internal Server Error
2025-10-15 14:22:31,030 ERROR: [httptools_impl:run_asgi] Exception in ASGI application
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/uvicorn/protocols/http/httptools_impl.py", line 375, in run_asgi
    result = await app(self.scope, self.receive, self.send)
  File "/usr/local/lib/python3.9/site-packages/uvicorn/middleware/proxy_headers.py", line 75, in __call__
    return await self.app(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/fastapi/applications.py", line 1054, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/applications.py", line 123, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/errors.py", line 186, in __call__
    raise exc
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/cors.py", line 93, in __call__
    await self.simple_response(scope, receive, send, request_headers=headers)
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/cors.py", line 148, in simple_response
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/exceptions.py", line 65, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.9/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.9/site-packages/starlette/routing.py", line 756, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/routing.py", line 776, in app
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/routing.py", line 297, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/routing.py", line 77, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.9/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.9/site-packages/starlette/routing.py", line 72, in app
    response = await func(request)
  File "/usr/local/lib/python3.9/site-packages/fastapi/routing.py", line 278, in app
    raw_response = await run_endpoint_function(
  File "/usr/local/lib/python3.9/site-packages/fastapi/routing.py", line 193, in run_endpoint_function
    return await run_in_threadpool(dependant.call, **values)
  File "/usr/local/lib/python3.9/site-packages/starlette/concurrency.py", line 42, in run_in_threadpool
    return await anyio.to_thread.run_sync(func, *args)
  File "/usr/local/lib/python3.9/site-packages/anyio/to_thread.py", line 33, in run_sync
    return await get_asynclib().run_sync_in_worker_thread(
  File "/usr/local/lib/python3.9/site-packages/anyio/_backends/_asyncio.py", line 877, in run_sync_in_worker_thread
    return await future
  File "/usr/local/lib/python3.9/site-packages/anyio/_backends/_asyncio.py", line 807, in run
    result = context.run(func, *args)
  File "/app/./api/gpus.py", line 141, in create_gpu_schedule
    if schedule.starting_date > max_advance_date:
TypeError: can't compare offset-naive and offset-aware datetimes