Presto Native - Prestissimo#

Prestissimo is a C++ drop-in replacement for Presto workers based on the Velox library. It implements the same RESTful endpoints as Java workers using the Proxygen C++ HTTP framework. Since communication with the Java coordinator and across workers is only done using the REST endpoints, Prestissimo does not use JNI and it is commonly deployed in such a way as to avoid having a JVM process on worker nodes.

Prestissimo’s codebase is located at presto-native-execution.

Endpoints#

HTTP endpoints related to tasks are registered to Proxygen in TaskResource.cpp. Important endpoints implemented include:

  • POST: v1/task: This processes a TaskUpdateRequest

  • GET: v1/task: This returns a serialized TaskInfo (used for comprehensive metrics, may be reported less frequently)

  • GET: v1/task/status: This returns a serialized TaskStatus (used for query progress tracking, must be reported frequently)

Other HTTP endpoints include:

  • POST: v1/memory * Reports memory, but no assignments are adjusted unlike in Java workers.

  • GET: v1/info

  • GET: v1/status

The request/response flow of Prestissimo is identical to Java workers. The tasks or new splits are registered via TaskUpdateRequest. Resource utilization and query progress are sent to the coordinator via task endpoints.

Remote Function Execution#

Prestissimo supports remote execution of scalar functions. This feature is useful for cases when the function code is not written in C++, or if for security or flexibility reasons the function code cannot be linked to the same executable as the main engine.

Remote function signatures need to be provided using a JSON file, following the format implemented by JsonFileBasedFunctionNamespaceManager. The following properties allow the configuration of remote function execution:

remote-function-server.signature.files.directory.path#

  • Type: string

  • Default value: ""

The local filesystem path where JSON files containing remote function signatures are located. If not empty, the Presto native worker will recursively search, open, parse, and register function definitions from these JSON files.

remote-function-server.catalog-name#

  • Type: string

  • Default value: ""

The catalog name to be added as a prefix to the function names registered in Velox. The function name pattern registered is catalog.schema.function_name, where catalog is defined by this parameter, and schema and function_name are read from the input JSON file.

If empty, the function is registered as schema.function_name.

remote-function-server.serde#

  • Type: string

  • Default value: "presto_page"

The serialization/deserialization method to use when communicating with the remote function server. Supported values are presto_page or spark_unsafe_row.

remote-function-server.thrift.address#

  • Type: string

  • Default value: ""

The location (ip address or hostname) that hosts the remote function server, if any remote functions were registered using remote-function-server.signature.files.directory.path. If not specified, falls back to the loopback interface (::1)

remote-function-server.thrift.port#

  • Type: integer

  • Default value: 0

The port that hosts the remote function server. If not specified and remote functions are trying to be registered, an exception is thrown.

remote-function-server.thrift.uds-path#

  • Type: string

  • Default value: ""

The UDS (unix domain socket) path to communicate with a local remote function server. If specified, takes precedence over remote-function-server.thrift.address and remote-function-server.thrift.port.

JWT authentication support#

Prestissimo supports JWT authentication for internal communication. For details on the generally supported parameters visit JWT.

There is also an additional parameter:

internal-communication.jwt.expiration-seconds#

  • Type integer

  • Default value: 300

There is a time period between creating the JWT on the client and verification by the server. If the time period is less than or equal to the parameter value, the request is valid. If the time period exceeds the parameter value, the request is rejected as authentication failure (HTTP 401).

Async Data Cache and Prefetching#

num-connector-io-threads#

  • Type integer

  • Default value: 30

  • Presto on Spark default value: 0

Size of IO executor for connectors to do preload/prefetch. Prefetch is disabled if num-connector-io-threads is set to zero.

async-data-cache-enabled#

  • Type bool

  • Default value: true

  • Presto on Spark default value: false

Whether async data cache is enabled. Setting async-data-cache-enabled to false disables split prefetching in table scan.

async-cache-ssd-gb#

  • Type integer

  • Default value: 0

Size of the SSD cache when async data cache is enabled. Must be zero if async-data-cache-enabled is false.

enable-old-task-cleanup#

  • Type bool

  • Default value: true

  • Presto on Spark default value: false

Enable periodic clean up of old tasks. This is true for Prestissimo, however for Presto on Spark this defaults to false as zombie/stuck tasks are handled by spark via speculative execution.

old-task-cleanup-ms#

  • Type integer

  • Default value: 60000

Duration after which a task should be considered as old and will be eligible for cleanup. Only applicable when enable-old-task-cleanup is true. Old task is defined as a PrestoTask which has not received heartbeat for at least old-task-cleanup-ms, or is not running and has an end time more than old-task-cleanup-ms ago.