The thread pool

The thread pool — The thread pool

Functions

void * (*TPGetTaskFunc) ()
void (*TPWorkFunc) ()
void (*TPFinalFunc) ()
int run_threads ()
signed int get_status_label ()

Types and Values

extern pthread_mutex_t stderr_lock

Includes

#include "thread-pool.h"

Description

The thread pool helps when running many tasks in parallel. It takes care of starting and stopping threads, and presents a relatively simple interface to the individual programs.

Functions

TPGetTaskFunc ()

void *
(*TPGetTaskFunc) (void *qargs);

Parameters

qargs

The queue_args pointer which was given to run_threads().

 

Returns

A pointer which will be passed to the worker function.

This function is called, non-reentrantly, to get a new work item to give to your work function. The stuff you need to generate the new work item should have been stored in qargs which was passed to run_threads().


TPWorkFunc ()

void
(*TPWorkFunc) (void *work,
               int cookie);

This function is called, reentrantly, for each work item.

Parameters

work

The queue_args pointer which was given to run_threads().

 

cookie

A small integral number which is guaranteed to be unique among all currently running threads.

 

TPFinalFunc ()

void
(*TPFinalFunc) (void *qargs,
                void *work);

This function is called, non-reentrantly, after each work item has been completed. A typical use might be to update some counters inside qargs according to fields withing work which were filled by your 'work' function.

Parameters

qargs

The queue_args pointer which was given to run_threads().

 

work

The pointer which was returned by your get_task function.

 

run_threads ()

int
run_threads (int n_threads,
             TPWorkFunc work,
             TPGetTaskFunc get_task,
             TPFinalFunc final,
             void *queue_args,
             int max,
             int cpu_num,
             int cpu_groupsize,
             int cpu_offset);

'get_task' will be called every time a worker is idle. It returns either NULL, indicating that no further work is available, or a pointer which will be passed to 'work'.

'final' will be called once per image, and will be given both queue_args and the last task pointer.

'get_task' and 'final' will be called only under lock, and so do NOT need to be re-entrant or otherwise thread safe. 'work', of course, needs to be thread safe.

Work will stop after 'max' tasks have been processed whether get_task returned NULL or not. If "max" is zero, all tasks will be processed.

Parameters

n_threads

The number of threads to run in parallel

 

work

The function to be called to do the work

 

get_task

The function which will determine the next unassigned task

 

final

The function which will be called to clean up after a task

 

queue_args

A pointer to any data required to determine the next task

 

max

Stop calling get_task after starting this number of jobs

 

cpu_num

The number of CPUs in the system

 

cpu_groupsize

The group size into which the CPUs are grouped

 

cpu_offset

The CPU group number at which to start pinning threads

 

Returns

The number of tasks completed.


get_status_label ()

signed int
get_status_label (void);

Types and Values

stderr_lock

extern pthread_mutex_t stderr_lock;