#### What this does ####
# identifies least busy deployment
# How is this achieved?
# - Before each call, have the router print the state of requests {"deployment": "requests_in_flight"}
# - use litellm.input_callbacks to log when a request is just about to be made to a model - {"deployment-id": traffic}
# - use litellm.success + failure callbacks to log when a request completed
# - in get_available_deployment, for a given model group name -> pick based on traffic
import random
from typing import Optional
from litellm.caching.caching import DualCache
from litellm.integrations.custom_logger import CustomLogger
class LeastBusyLoggingHandler(CustomLogger):
test_flag: bool = False
logged_success: int = 0
logged_failure: int = 0
def __init__(self, router_cache: DualCache, model_list: list):
self.router_cache = router_cache
self.mapping_deployment_to_id: dict = {}
self.model_list = model_list
def log_pre_api_call(self, model, messages, kwargs):
"""
Log when a model is being used.
Caching based on model group.
"""
try:
if kwargs["litellm_params"].get("metadata") is None:
pass
else:
model_group = kwargs["litellm_params"]["metadata"].get(
"model_group", None
)
id = kwargs["litellm_params"].get("model_info", {}).get("id", None)
if model_group is None or id is None:
return
elif isinstance(id, int):
id = str(id)
request_count_api_key = f"{model_group}_request_count"
# update cache
request_count_dict = (
self.router_cache.get_cache(key=request_count_api_key) or {}
)
request_count_dict[id] = request_count_dict.get(id, 0) + 1
self.router_cache.set_cache(
key=request_count_api_key, value=request_count_dict
)
except Exception:
pass
def log_success_event(self, kwargs, response_obj, start_time, end_time):
try:
if kwargs["litellm_params"].get("metadata") is None:
pass
else:
model_group = kwargs["litellm_params"]["metadata"].get(
"model_group", None
)
id = kwargs["litellm_params"].get("model_info", {}).get("id", None)
if model_group is None or id is None:
return
elif isinstance(id, int):
id = str(id)
request_count_api_key = f"{model_group}_request_count"
# decrement count in cache
request_count_dict = (
self.router_cache.get_cache(key=request_count_api_key) or {}
)
request_count_value: Optional[int] = request_count_dict.get(id, 0)
if request_count_value is None:
return
request_count_dict[id] = request_count_value - 1
self.router_cache.set_cache(
key=request_count_api_key, value=request_count_dict
)
### TESTING ###
if self.test_flag:
self.logged_success += 1
except Exception:
pass
def log_failure_event(self, kwargs, response_obj, start_time, end_time):
try:
if kwargs["litellm_params"].get("metadata") is None:
pass
else:
model_group = kwargs["litellm_params"]["metadata"].get(
"model_group", None
)
id = kwargs["litellm_params"].get("model_info", {}).get("id", None)
if model_group is None or id is None:
return
elif isinstance(id, int):
id = str(id)
request_count_api_key = f"{model_group}_request_count"
# decrement count in cache
request_count_dict = (
self.router_cache.get_cache(key=request_count_api_key) or {}
)
request_count_value: Optional[int] = request_count_dict.get(id, 0)
if request_count_value is None:
return
request_count_dict[id] = request_count_value - 1
self.router_cache.set_cache(
key=request_count_api_key, value=request_count_dict
)
### TESTING ###
if self.test_flag:
self.logged_failure += 1
except Exception:
pass
async def async_log_success_event(self, kwargs, response_obj, start_time, end_time):
try:
if kwargs["litellm_params"].get("metadata") is None:
pass
else:
model_group = kwargs["litellm_params"]["metadata"].get(
"model_group", None
)
id = kwargs["litellm_params"].get("model_info", {}).get("id", None)
if model_group is None or id is None:
return
elif isinstance(id, int):
id = str(id)
request_count_api_key = f"{model_group}_request_count"
# decrement count in cache
request_count_dict = (
await self.router_cache.async_get_cache(key=request_count_api_key)
or {}
)
request_count_value: Optional[int] = request_count_dict.get(id, 0)
if request_count_value is None:
return
request_count_dict[id] = request_count_value - 1
await self.router_cache.async_set_cache(
key=request_count_api_key, value=request_count_dict
)
### TESTING ###
if self.test_flag:
self.logged_success += 1
except Exception:
pass
async def async_log_failure_event(self, kwargs, response_obj, start_time, end_time):
try:
if kwargs["litellm_params"].get("metadata") is None:
pass
else:
model_group = kwargs["litellm_params"]["metadata"].get(
"model_group", None
)
id = kwargs["litellm_params"].get("model_info", {}).get("id", None)
if model_group is None or id is None:
return
elif isinstance(id, int):
id = str(id)
request_count_api_key = f"{model_group}_request_count"
# decrement count in cache
request_count_dict = (
await self.router_cache.async_get_cache(key=request_count_api_key)
or {}
)
request_count_value: Optional[int] = request_count_dict.get(id, 0)
if request_count_value is None:
return
request_count_dict[id] = request_count_value - 1
await self.router_cache.async_set_cache(
key=request_count_api_key, value=request_count_dict
)
### TESTING ###
if self.test_flag:
self.logged_failure += 1
except Exception:
pass
def _get_available_deployments(
self,
healthy_deployments: list,
all_deployments: dict,
):
"""
Helper to get deployments using least busy strategy
"""
for d in healthy_deployments:
## if healthy deployment not yet used
if d["model_info"]["id"] not in all_deployments:
all_deployments[d["model_info"]["id"]] = 0
# map deployment to id
# pick least busy deployment
min_traffic = float("inf")
min_deployment = None
for k, v in all_deployments.items():
if v < min_traffic:
min_traffic = v
min_deployment = k
if min_deployment is not None:
## check if min deployment is a string, if so, cast it to int
for m in healthy_deployments:
if m["model_info"]["id"] == min_deployment:
return m
min_deployment = random.choice(healthy_deployments)
else:
min_deployment = random.choice(healthy_deployments)
return min_deployment
def get_available_deployments(
self,
model_group: str,
healthy_deployments: list,
):
"""
Sync helper to get deployments using least busy strategy
"""
request_count_api_key = f"{model_group}_request_count"
all_deployments = self.router_cache.get_cache(key=request_count_api_key) or {}
return self._get_available_deployments(
healthy_deployments=healthy_deployments,
all_deployments=all_deployments,
)
async def async_get_available_deployments(
self, model_group: str, healthy_deployments: list
):
"""
Async helper to get deployments using least busy strategy
"""
request_count_api_key = f"{model_group}_request_count"
all_deployments = (
await self.router_cache.async_get_cache(key=request_count_api_key) or {}
)
return self._get_available_deployments(
healthy_deployments=healthy_deployments,
all_deployments=all_deployments,
)
