jemalloc-percpu-arena-test.c

/**
 * Reproducer for percpu_arena jemalloc issue [1].
 * Requires debug jemalloc (w/o NDEBUG to include assert()s)
 *
 *   [1]: https://github.com/jemalloc/jemalloc/pull/1676
 *
 * $ gcc -g3 -o /tmp/sched /tmp/sched.c
 * $ MALLOC_CONF=percpu_arena:percpu LD_PRELOAD=jemalloc/build/lib/libjemalloc.so taskset --cpu-list 3 /tmp/sched
 * <jemalloc>: ../src/jemalloc.c:321: Failed assertion: "ind <= narenas_total_get()"
 * Aborted (core dumped)
 */

#define _GNU_SOURCE
#include <sched.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int main()
{
    cpu_set_t set;
    int err;

    err = sched_getaffinity(0, sizeof(set), &set);
    assert(!err);

    printf("sched_getcpu() = %i\n", sched_getcpu());
    printf("sched_getaffinity() = %i\n", CPU_COUNT(&set));
    printf("_SC_NPROCESSORS_ONLN = %i\n", sysconf(_SC_NPROCESSORS_ONLN));

    return EXIT_SUCCESS;
}

No sched_setaffinity(), since you can have different number of CPUs, if it will not hit the assert() then change the cpu in taskset (or you have non-debug jemalloc, i.e. w/ NDEBUG)