* Thread pool test program.
* Parallel sum.
* C version of http://en.cppreference.com/w/cpp/thread/async
* Written by G. Back for CS3214 Fall 2014.
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#include
#include
#include
#include
#include
#include
#include
#include
#include “threadpool.h”
#include “threadpool_lib.h”
/* Data to be passed to callable. */
struct problem_parameters {
unsigned beg, end;
#define GRANULARITY 100
static void *
parallel_sum(struct thread_pool * pool, void * _data)
struct problem_parameters * p = _data;
int i, len = p->end – p->beg;
if (len < GRANULARITY) {
uintptr_t sum = 0;
int * v = p->v;
for (i = p->beg; i < p->end; i++)
sum += v[i];
return (void *) sum;
int mid = p->beg + len / 2;
struct problem_parameters left_half = {
.beg = p->beg, .end = mid, .v = p->v
struct problem_parameters right_half = {
.beg = mid, .end = p->end, .v = p->v
struct future * f = thread_pool_submit(pool, parallel_sum, &right_half);
uintptr_t lresult = (uintptr_t) parallel_sum(pool, &left_half);
uintptr_t rresult = (uintptr_t) future_get(f);
future_free(f);
return (void *)(lresult + rresult);
static void usage(char *av0, int nthreads) {
fprintf(stderr, “Usage: %s [-n
” -n number of threads in pool, default %d\n”
, av0, nthreads);
main(int ac, char *av[])
int nthreads = 4;
while ((c = getopt(ac, av, “n:h”)) != EOF) {
switch (c) {
nthreads = atoi(optarg);
usage(av[0], nthreads);
if (optind == ac)
usage(av[0], nthreads);
int len = atoi(av[optind]);
struct thread_pool * pool = thread_pool_new(nthreads);
int * v = malloc(sizeof(int) * len);
struct problem_parameters roottask = {
.beg = 0, .end = len, .v = v,
unsigned long long realsum = 0;
for (i = 0; i < len; i++) {
v[i] = i % 3;
realsum += v[i];
printf("starting...\n");
struct benchmark_data* bdata = start_benchmark();
struct future *f = thread_pool_submit(pool, parallel_sum, &roottask);
unsigned long long sum = (unsigned long long) future_get(f);
stop_benchmark(bdata);
future_free(f);
if (sum != realsum) {
printf("result %lld should be %lld\n", sum, realsum);
printf("result ok.\n");
report_benchmark_results(bdata);
thread_pool_shutdown_and_destroy(pool);
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