Collective

Experimental support for exposing internal communicator in XGBoost. More...

Functions
int	XGCommunicatorInit (char const *config)
	Initialize the collective communicator. More...
int	XGCommunicatorFinalize (void)
	Finalize the collective communicator. More...
int	XGCommunicatorGetRank (void)
	Get rank of current process. More...
int	XGCommunicatorGetWorldSize (void)
	Get total number of processes. More...
int	XGCommunicatorIsDistributed (void)
	Get if the communicator is distributed. More...
int	XGCommunicatorPrint (char const *message)
	Print the message to the communicator. More...
int	XGCommunicatorGetProcessorName (const char **name_str)
	Get the name of the processor. More...
int	XGCommunicatorBroadcast (void *send_receive_buffer, size_t size, int root)
	Broadcast a memory region to all others from root. This function is NOT thread-safe. More...
int	XGCommunicatorAllreduce (void *send_receive_buffer, size_t count, int data_type, int op)
	Perform in-place allreduce. This function is NOT thread-safe. More...

Detailed Description

Experimental support for exposing internal communicator in XGBoost.

Function Documentation

XGCommunicatorAllreduce()

int XGCommunicatorAllreduce	(	void *	send_receive_buffer,
		size_t	count,
		int	data_type,
		int	op
	)

Perform in-place allreduce. This function is NOT thread-safe.

Example Usage: the following code gives sum of the result

vector<int> data(10);
...
Allreduce(&data[0], data.size(), DataType:kInt32, Op::kSum);
...

Parameters

send_receive_buffer	Buffer for both sending and receiving data.
count	Number of elements to be reduced.
data_type	Enumeration of data type, see xgboost::collective::DataType in communicator.h.
op	Enumeration of operation type, see xgboost::collective::Operation in communicator.h.

Returns

0 for success, -1 for failure.

XGCommunicatorBroadcast()

int XGCommunicatorBroadcast	(	void *	send_receive_buffer,
		size_t	size,
		int	root
	)

Broadcast a memory region to all others from root. This function is NOT thread-safe.

Example:

int a = 1;
Broadcast(&a, sizeof(a), root);

Parameters

send_receive_buffer	Pointer to the send or receive buffer.
size	Size of the data.
root	The process rank to broadcast from.

Returns

0 for success, -1 for failure.

XGCommunicatorFinalize()

int XGCommunicatorFinalize

(

void

)

Finalize the collective communicator.

Call this function after you finished all jobs.

Returns

0 for success, -1 for failure.

XGCommunicatorGetProcessorName()

int XGCommunicatorGetProcessorName

(

const char **

name_str

)

Get the name of the processor.

Parameters

name_str

Pointer to received returned processor name.

Returns

0 for success, -1 for failure.

XGCommunicatorGetRank()

int XGCommunicatorGetRank

(

void

)

Get rank of current process.

Returns

Rank of the worker.

XGCommunicatorGetWorldSize()

int XGCommunicatorGetWorldSize

(

void

)

Get total number of processes.

Returns

Total world size.

XGCommunicatorInit()

int XGCommunicatorInit

(

char const *

config

)

Initialize the collective communicator.

Currently the communicator API is experimental, function signatures may change in the future without notice.

Call this once before using anything.

The additional configuration is not required. Usually the communicator will detect settings from environment variables.

Parameters

config

JSON encoded configuration. Accepted JSON keys are: xgboost_communicator: The type of the communicator. Can be set as an environment variable. rabit: Use Rabit. This is the default if the type is unspecified. mpi: Use MPI. federated: Use the gRPC interface for Federated Learning. Only applicable to the Rabit communicator (these are case-sensitive): rabit_tracker_uri: Hostname of the tracker. rabit_tracker_port: Port number of the tracker. rabit_task_id: ID of the current task, can be used to obtain deterministic rank assignment. rabit_world_size: Total number of workers. rabit_hadoop_mode: Enable Hadoop support. rabit_tree_reduce_minsize: Minimal size for tree reduce. rabit_reduce_ring_mincount: Minimal count to perform ring reduce. rabit_reduce_buffer: Size of the reduce buffer. rabit_bootstrap_cache: Size of the bootstrap cache. rabit_debug: Enable debugging. rabit_timeout: Enable timeout. rabit_timeout_sec: Timeout in seconds. rabit_enable_tcp_no_delay: Enable TCP no delay on Unix platforms. Only applicable to the Rabit communicator (these are case-sensitive, and can be set as environment variables): DMLC_TRACKER_URI: Hostname of the tracker. DMLC_TRACKER_PORT: Port number of the tracker. DMLC_TASK_ID: ID of the current task, can be used to obtain deterministic rank assignment. DMLC_ROLE: Role of the current task, "worker" or "server". DMLC_NUM_ATTEMPT: Number of attempts after task failure. DMLC_WORKER_CONNECT_RETRY: Number of retries to connect to the tracker. Only applicable to the Federated communicator (use upper case for environment variables, use lower case for runtime configuration): federated_server_address: Address of the federated server. federated_world_size: Number of federated workers. federated_rank: Rank of the current worker. federated_server_cert: Server certificate file path. Only needed for the SSL mode. federated_client_key: Client key file path. Only needed for the SSL mode. federated_client_cert: Client certificate file path. Only needed for the SSL mode.

Returns

0 for success, -1 for failure.

XGCommunicatorIsDistributed()

int XGCommunicatorIsDistributed

(

void

)

Get if the communicator is distributed.

Returns

True if the communicator is distributed.

XGCommunicatorPrint()

int XGCommunicatorPrint

(

char const *

message

)

Print the message to the communicator.

This function can be used to communicate the information of the progress to the user who monitors the communicator.

Parameters

message

The message to be printed.

Returns

0 for success, -1 for failure.