diff -r 000000000000 -r 6474c204b198 memory/jemalloc/src/test/thread_arena.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/memory/jemalloc/src/test/thread_arena.c	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,80 @@
+#define	JEMALLOC_MANGLE
+#include "jemalloc_test.h"
+
+#define	NTHREADS 10
+
+void *
+je_thread_start(void *arg)
+{
+	unsigned main_arena_ind = *(unsigned *)arg;
+	void *p;
+	unsigned arena_ind;
+	size_t size;
+	int err;
+
+	p = malloc(1);
+	if (p == NULL) {
+		malloc_printf("%s(): Error in malloc()\n", __func__);
+		return (void *)1;
+	}
+
+	size = sizeof(arena_ind);
+	if ((err = mallctl("thread.arena", &arena_ind, &size, &main_arena_ind,
+	    sizeof(main_arena_ind)))) {
+		malloc_printf("%s(): Error in mallctl(): %s\n", __func__,
+		    strerror(err));
+		return (void *)1;
+	}
+
+	size = sizeof(arena_ind);
+	if ((err = mallctl("thread.arena", &arena_ind, &size, NULL,
+	    0))) {
+		malloc_printf("%s(): Error in mallctl(): %s\n", __func__,
+		    strerror(err));
+		return (void *)1;
+	}
+	assert(arena_ind == main_arena_ind);
+
+	return (NULL);
+}
+
+int
+main(void)
+{
+	int ret = 0;
+	void *p;
+	unsigned arena_ind;
+	size_t size;
+	int err;
+	je_thread_t threads[NTHREADS];
+	unsigned i;
+
+	malloc_printf("Test begin\n");
+
+	p = malloc(1);
+	if (p == NULL) {
+		malloc_printf("%s(): Error in malloc()\n", __func__);
+		ret = 1;
+		goto label_return;
+	}
+
+	size = sizeof(arena_ind);
+	if ((err = mallctl("thread.arena", &arena_ind, &size, NULL, 0))) {
+		malloc_printf("%s(): Error in mallctl(): %s\n", __func__,
+		    strerror(err));
+		ret = 1;
+		goto label_return;
+	}
+
+	for (i = 0; i < NTHREADS; i++) {
+		je_thread_create(&threads[i], je_thread_start,
+		    (void *)&arena_ind);
+	}
+
+	for (i = 0; i < NTHREADS; i++)
+		je_thread_join(threads[i], (void *)&ret);
+
+label_return:
+	malloc_printf("Test end\n");
+	return (ret);
+}