tf::RandomPartitioner class

class to construct a random partitioner for scheduling parallel algorithms

Template parameters
C	closure wrapper type (default tf::DefaultClosureWrapper)

Similar to tf::DynamicPartitioner, the partitioner splits iterations into many partitions but each with a random chunk size in the range, c = [alpha * N * W, beta * N * W]. By default, alpha is 0.01 and beta is 0.5, respectively.

In addition to partition size, the application can specify a closure wrapper for a random partitioner. A closure wrapper allows the application to wrapper a partitioned task (i.e., closure) with a custom function object that performs additional tasks. For example:

std::atomic<int> count = 0;
tf::Taskflow taskflow;
taskflow.for_each_index(0, 100, 1, 
  [](){                 
    printf("%d\n", i); 
  },
  tf::RandomPartitioner(0, [](auto&& closure){
    // do something before invoking the partitioned task
    // ...
    
    // invoke the partitioned task
    closure();

    // do something else after invoking the partitioned task
    // ...
  }
);
executor.run(taskflow).wait();

Base classes

template<typename C = DefaultClosureWrapper> class PartitionerBase<DefaultClosureWrapper>: class to derive a partitioner for scheduling parallel algorithms

Public static functions

static auto type() -> PartitionerType constexpr: queries the partition type (dynamic)

Constructors, destructors, conversion operators

RandomPartitioner() defaulted: default constructor
RandomPartitioner(size_t sz) explicit: construct a dynamic partitioner with the given chunk size
RandomPartitioner(size_t sz, C&& closure) explicit: construct a random partitioner with the given chunk size and the closure
RandomPartitioner(float alpha, float beta): constructs a random partitioner with the given parameters
RandomPartitioner(float alpha, float beta, C&& closure): constructs a random partitioner with the given parameters and the closure

Public functions

auto alpha() const -> float: queries the alpha value
auto beta() const -> float: queries the beta value
auto chunk_size_range(size_t N, size_t W) const -> std::pair<size_t, size_t>: queries the range of chunk size

Function documentation

template<typename C>
std::pair<size_t, size_t> tf::RandomPartitioner<C>::chunk_size_range(size_t N, size_t W) const

queries the range of chunk size

Parameters
N	number of iterations
W	number of workers

#include <taskflow/algorithm/partitioner.hpp> template<typename C = DefaultClosureWrapper> tf::RandomPartitioner class