An in memory rate limiter based on a token bucket algorithm.
This is an in memory rate limiter, so it cannot rate limit across different processes.
The rate limiter only allows time-based rate limiting and does not take into account any information about the input or the output, so it cannot be used to rate limit based on the size of the request.
It is thread safe and can be used in either a sync or async context.
The in memory rate limiter is based on a token bucket. The bucket is filled with tokens at a given rate. Each request consumes a token. If there are not enough tokens in the bucket, the request is blocked until there are enough tokens.
These tokens have nothing to do with LLM tokens. They are just a way to keep track of how many requests can be made at a given time.
Current limitations:
InMemoryRateLimiter(
self,
*,
requests_per_second: float = 1,
check_every_n_seconds: float = 0.1,
max_bucket_size: float = 1
)Example:
import time
from langchain_core.rate_limiters import InMemoryRateLimiter
rate_limiter = InMemoryRateLimiter(
requests_per_second=0.1, # <-- Can only make a request once every 10 seconds!!
check_every_n_seconds=0.1, # Wake up every 100 ms to check whether allowed to make a request,
max_bucket_size=10, # Controls the maximum burst size.
)
from langchain_anthropic import ChatAnthropic
model = ChatAnthropic(
model_name="claude-sonnet-4-5-20250929", rate_limiter=rate_limiter
)
for _ in range(5):
tic = time.time()
model.invoke("hello")
toc = time.time()
print(toc - tic)| Name | Type | Description |
|---|---|---|
requests_per_second | float | Default: 1The number of tokens to add per second to the bucket. The tokens represent "credit" that can be used to make requests. |
check_every_n_seconds | float | Default: 0.1Check whether the tokens are available every this many seconds. Can be a float to represent fractions of a second. |
max_bucket_size | float | Default: 1The maximum number of tokens that can be in the bucket.
Must be at least |
Attempt to acquire a token from the rate limiter.
This method blocks until the required tokens are available if blocking
is set to True.
If blocking is set to False, the method will immediately return the result
of the attempt to acquire the tokens.
Attempt to acquire a token from the rate limiter. Async version.
This method blocks until the required tokens are available if blocking
is set to True.
If blocking is set to False, the method will immediately return the result
of the attempt to acquire the tokens.