maspack.concurrency

Class ParallelLoop

java.lang.Object

maspack.concurrency.ParallelLoop

public class ParallelLoop
extends java.lang.Object

Simple utility for executing index-range loops in parallel, using a shared ForkJoinPool. The range [0, n) is divided into contiguous chunks, each of which is passed to a ParallelLoop.RangeBody. Since each chunk is executed by a single thread, bodies can allocate per-chunk scratch storage without needing thread-local variables.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	ParallelLoop.RangeBody Body of a parallel loop, called for the index sub-range [lo, hi).

Constructor Summary

Constructors

Constructor and Description
ParallelLoop()

Method Summary

Modifier and Type	Method and Description
static void	forRange(int n, int minChunk, ParallelLoop.RangeBody body) Executes body over the range [0, n), dividing the range into contiguous chunks that are processed in parallel.
static int	getNumThreads() Queries the number of threads used for parallel loops.
static int	numChunks(int n, int minChunk) Returns the number of chunks that forRange(int, int, maspack.concurrency.ParallelLoop.RangeBody) will use for a given range size and minimum chunk size.
static void	setNumThreads(int num) Sets the number of threads used for parallel loops.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ParallelLoop

public ParallelLoop()

Method Detail

setNumThreads

public static void setNumThreads(int num)

Sets the number of threads used for parallel loops. A value <= 1 causes loops to be executed serially in the calling thread.

Parameters:

num - number of threads

getNumThreads

public static int getNumThreads()

Queries the number of threads used for parallel loops.

Returns:

number of threads

numChunks

public static int numChunks(int n,
                            int minChunk)

Returns the number of chunks that forRange(int, int, maspack.concurrency.ParallelLoop.RangeBody) will use for a given range size and minimum chunk size.

Parameters:

n - range size

minChunk - minimum chunk size

Returns:

number of chunks

forRange

public static void forRange(int n,
                            int minChunk,
                            ParallelLoop.RangeBody body)

Executes body over the range [0, n), dividing the range into contiguous chunks that are processed in parallel. If only one chunk is needed, body is called directly in the calling thread. The method returns after all chunks have completed. Any exception thrown by a chunk is rethrown in the calling thread.

Parameters:

n - range size

minChunk - minimum size of each chunk

body - loop body