fftw_concurrency_test.c

// gcc -o fftw_concurrency_test fftw_concurrency_test.c -Wall -pthread `pkg-config --cflags --libs fftw3f` -lfftw3f_threads

/* 2 is sufficient to produce crashes, 8 makes it more likely */
#define MAXTHREAD 8

/* there is no c-header for this, yet */
extern void fftwf_make_planner_thread_safe ();

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <fftw3.h>

struct FFTAnalysis {
	float *fft_in;
	float *fft_out;
	fftwf_plan fftplan;
};

static void test_fftw(int window_size) {
	struct FFTAnalysis *ft = calloc (1, sizeof(struct FFTAnalysis));
	ft->fft_in  = (float *) fftwf_malloc(sizeof(float) * window_size);
	ft->fft_out = (float *) fftwf_malloc(sizeof(float) * window_size);
	ft->fftplan = fftwf_plan_r2r_1d(window_size, ft->fft_in, ft->fft_out, FFTW_R2HC, FFTW_MEASURE);
	fftwf_destroy_plan(ft->fftplan);
	fftwf_free(ft->fft_in);
	fftwf_free(ft->fft_out);
	free(ft);
}

static void * main_thread (void *arg) {
	int v = *((int*)arg);
	printf("window size: %d\n", v);
	usleep(1000);
	test_fftw (v);
	pthread_exit (0);
	return 0;
}

int main (int argc, char **argv) {
	int i;
	int bs[MAXTHREAD];
	pthread_t thread[MAXTHREAD];

	fftwf_make_planner_thread_safe ();

	for (i = 0; i < MAXTHREAD; ++i) {
		bs[i] = 1 << (6 + (i % 5));
		pthread_create (&thread[i], NULL, &main_thread, &bs[i]);
	}
	for (i = 0; i < MAXTHREAD; ++i) {
		pthread_join (thread[i], NULL);
	}
	return 0;
}