litellm/docs/my-website/docs/proxy/db_deadlocks.md

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High Availability Setup (Resolve DB Deadlocks)

Resolve any Database Deadlocks you see in high traffic by using this setup

What causes the problem?

LiteLLM writes UPDATE and UPSERT queries to the DB. When using 10+ instances of LiteLLM, these queries can cause deadlocks since each instance could simultaneously attempt to update the same user_id, team_id, key etc.

How the high availability setup fixes the problem

• All instances will write to a Redis queue instead of the DB.
• A single instance will acquire a lock on the DB and flush the redis queue to the DB.

How it works

Stage 1. Each instance writes updates to redis

Each instance will accumulate the spend updates for a key, user, team, etc and write the updates to a redis queue.

<Image img={require('../../img/deadlock_fix_1.png')} style={{ width: '900px', height: 'auto' }} />

Each instance writes updates to redis

Stage 2. A single instance flushes the redis queue to the DB

A single instance will acquire a lock on the DB and flush all elements in the redis queue to the DB.

• 1 instance will attempt to acquire the lock for the DB update job
• The status of the lock is stored in redis
• If the instance acquires the lock to write to DB
  • It will read all updates from redis
  • Aggregate all updates into 1 transaction
  • Write updates to DB
  • Release the lock
• Note: Only 1 instance can acquire the lock at a time, this limits the number of instances that can write to the DB at once

<Image img={require('../../img/deadlock_fix_2.png')} style={{ width: '900px', height: 'auto' }} />

A single instance flushes the redis queue to the DB

Usage

Required components

• Redis
• Postgres

Setup on LiteLLM config

You can enable using the redis buffer by setting use_redis_transaction_buffer: true in the general_settings section of your proxy_config.yaml file.

Note: This setup requires litellm to be connected to a redis instance.

general_settings:
  use_redis_transaction_buffer: true

litellm_settings:
  cache: True
  cache_params:
    type: redis
    supported_call_types: [] # Optional: Set cache for proxy, but not on the actual llm api call

Monitoring

LiteLLM emits the following prometheus metrics to monitor the health/status of the in memory buffer and redis buffer.

Metric Name	Description	Storage Type
litellm_pod_lock_manager_size	Indicates which pod has the lock to write updates to the database.	Redis
litellm_in_memory_daily_spend_update_queue_size	Number of items in the in-memory daily spend update queue. These are the aggregate spend logs for each user.	In-Memory
litellm_redis_daily_spend_update_queue_size	Number of items in the Redis daily spend update queue. These are the aggregate spend logs for each user.	Redis
litellm_in_memory_spend_update_queue_size	In-memory aggregate spend values for keys, users, teams, team members, etc.	In-Memory
litellm_redis_spend_update_queue_size	Redis aggregate spend values for keys, users, teams, etc.	Redis

Troubleshooting: Redis Connection Errors

You may see errors like:

LiteLLM Redis Caching: async async_increment() - Got exception from REDIS No connection available., Writing value=21
LiteLLM Redis Caching: async set_cache_pipeline() - Got exception from REDIS No connection available., Writing value=None

This means all available Redis connections are in use, and LiteLLM cannot obtain a new connection from the pool. This can happen under high load or with many concurrent proxy requests.

Solution:

• Increase the max_connections parameter in your Redis config section in proxy_config.yaml to allow more simultaneous connections. For example:

litellm_settings:
  cache: True
  cache_params:
    type: redis
    max_connections: 100  # Increase as needed for your traffic

Adjust this value based on your expected concurrency and Redis server capacity.