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fix: Add connection pre-warming for DynamoDB async client
Add warmup_connections parameter to DynamoDBOnlineStoreConfig and warm up connections via describe_limits inside initialize() method to solve cold-start latency. Also document warmup_connections in the performance tuning guide and reference docs. Fixes feast-dev#6060 Signed-off-by: Nithin <kumbam.nithingoud@gmail.com>
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‎docs/how-to-guides/online-server-performance-tuning.md‎

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@@ -324,6 +324,7 @@ online_store:
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batch_size: 100
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max_read_workers: 10
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consistent_reads: false
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warmup_connections: true
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max_pool_connections: 100
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keepalive_timeout: 30.0
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connect_timeout: 3
@@ -337,6 +338,7 @@ Key knobs:
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- **`batch_size`**: DynamoDB's `BatchGetItem` accepts up to 100 items per request. For 500 entities, this means 5 batches. Keep at 100 unless hitting the 16 MB response limit.
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- **`max_read_workers`**: Controls parallelism for batch reads. With 10 workers, those 5 batches run concurrently (~10 ms) instead of sequentially (~50 ms).
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- **`consistent_reads: false`**: Eventually consistent reads are faster and cheaper. Use `true` only if you need read-after-write consistency.
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- **`warmup_connections: true`**: Pre-warms the DynamoDB connection pool on server startup by making a lightweight call (`describe_limits`). This avoids a cold-start latency penalty (~20ms) on the very first feature request.
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- **`max_pool_connections`**: Increase for high-throughput deployments to improve HTTP connection reuse to the DynamoDB endpoint.
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- **`keepalive_timeout`**: Longer keep-alive reduces TLS handshake overhead on reused connections.
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- **`connect_timeout` / `read_timeout`**: Lower values fail fast, improving p99. Set aggressively if your retry strategy covers transient failures.

‎docs/reference/online-stores/dynamodb.md‎

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@@ -37,6 +37,7 @@ online_store:
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batch_size: 100
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max_read_workers: 10
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consistent_reads: false
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warmup_connections: true
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```
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{% endcode %}
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@@ -49,6 +50,7 @@ online_store:
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| `batch_size` | int | `100` | Number of items per BatchGetItem/BatchWriteItem request (max 100) |
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| `max_read_workers` | int | `10` | Maximum parallel threads for batch read operations. Higher values improve throughput for large batch reads but increase resource usage |
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| `consistent_reads` | bool | `false` | Whether to use strongly consistent reads (higher latency, guaranteed latest data) |
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| `warmup_connections` | bool | `false` | Whether to pre-warm the async connection pool on startup with a lightweight call (`describe_limits`) |
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| `tags` | dict | `null` | AWS resource tags added to each table |
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| `session_based_auth` | bool | `false` | Use AWS session-based client authentication |
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@@ -63,6 +65,8 @@ For high-throughput workloads with large entity counts, increase `max_read_worke
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**Batch Size**: Increase `batch_size` up to 100 to reduce the number of API calls. However, larger batches may hit DynamoDB's 16MB response limit for tables with large feature values.
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**Connection Warmup**: The DynamoDB async client does not establish actual TCP/TLS connections to the AWS endpoint on initialization. The very first feature retrieval request is penalized with a cold-start overhead (~20ms). Setting `warmup_connections: true` establishes the TCP connection pool during server startup.
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## Permissions
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Feast requires the following permissions in order to execute commands for DynamoDB online store:

‎sdk/python/feast/infra/online_stores/dynamodb.py‎

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@@ -76,6 +76,9 @@ class DynamoDBOnlineStoreConfig(FeastConfigBaseModel):
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consistent_reads: StrictBool = False
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"""Whether to read from Dynamodb by forcing consistent reads"""
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warmup_connections: StrictBool = False
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"""Whether to warm up the connection pool with a lightweight call on initialization"""
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tags: Union[Dict[str, str], None] = None
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"""AWS resource tags added to each table"""
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@@ -146,7 +149,7 @@ def __init__(self):
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async def initialize(self, config: RepoConfig):
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online_config = config.online_store
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await self._get_aiodynamodb_client(
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client = await self._get_aiodynamodb_client(
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online_config.region,
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online_config.max_pool_connections,
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online_config.keepalive_timeout,
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online_config.endpoint_url,
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)
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if online_config.warmup_connections:
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try:
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await client.describe_limits()
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except Exception:
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logger.warning(
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"Failed to warmup DynamoDB connection pool", exc_info=True
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)
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async def close(self):
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await self._aiodynamodb_close()
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‎sdk/python/tests/unit/infra/online_store/test_dynamodb_online_store.py‎

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@@ -75,6 +75,7 @@ def test_dynamodb_online_store_config_default():
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assert dynamodb_store_config.read_timeout == 10
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assert dynamodb_store_config.total_max_retry_attempts == 3
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assert dynamodb_store_config.retry_mode == "adaptive"
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assert dynamodb_store_config.warmup_connections is False
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def test_dynamodb_online_store_config_custom_params():
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batch_size=batch_size,
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endpoint_url=endpoint_url,
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table_name_template=table_name_template,
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warmup_connections=True,
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)
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assert dynamodb_store_config.type == "dynamodb"
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assert dynamodb_store_config.batch_size == batch_size
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assert dynamodb_store_config.endpoint_url == endpoint_url
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assert dynamodb_store_config.region == aws_region
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assert dynamodb_store_config.table_name_template == table_name_template
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assert dynamodb_store_config.warmup_connections is True
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@pytest.mark.asyncio
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async def test_dynamodb_online_store_warmup_connections():
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"""Test DynamoDBOnlineStore warmup connections in initialize method."""
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from unittest.mock import AsyncMock
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online_store = DynamoDBOnlineStore()
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# Mock _get_aiodynamodb_client to return a mock client
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mock_client = AsyncMock()
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mock_client.describe_limits = AsyncMock()
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online_store._get_aiodynamodb_client = AsyncMock(return_value=mock_client)
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# Test case 1: warmup_connections=True
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config_warmup = RepoConfig(
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registry=REGISTRY,
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project=PROJECT,
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provider=PROVIDER,
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online_store=DynamoDBOnlineStoreConfig(region=REGION, warmup_connections=True),
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offline_store=DaskOfflineStoreConfig(),
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entity_key_serialization_version=3,
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)
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await online_store.initialize(config_warmup)
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mock_client.describe_limits.assert_called_once()
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# Test case 2: warmup_connections=False
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mock_client.describe_limits.reset_mock()
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config_no_warmup = RepoConfig(
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registry=REGISTRY,
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project=PROJECT,
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provider=PROVIDER,
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online_store=DynamoDBOnlineStoreConfig(region=REGION, warmup_connections=False),
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offline_store=DaskOfflineStoreConfig(),
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entity_key_serialization_version=3,
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)
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await online_store.initialize(config_no_warmup)
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mock_client.describe_limits.assert_not_called()
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# Test case 3: warmup_connections=True and describe_limits raises an exception (should catch and log warning)
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mock_client.describe_limits.reset_mock()
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mock_client.describe_limits.side_effect = Exception("Connection failed")
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await online_store.initialize(config_warmup)
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mock_client.describe_limits.assert_called_once()
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def test_dynamodb_online_store_config_dynamodb_client(dynamodb_online_store):

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