How to use threads with libev - c

Question

I'm making a webcrawler and want to spawn a number of threads each with its own event loop to monitor network activity. Here is my code so far:
static void my_cb(EV_P_ struct ev_io *w, int revents)
{
GlobalInfo *g = (GlobalInfo *)w->data;
i = 0;
if (g->concurrent_connections < MAX_CONNECTIONS)
{
while (i < MAX_LOAD && i < MAX_CONNECTIONS - g->concurrent_connections)
{
add_url(g);
}
}
}
static int init(GlobalInfo *g)
{
int fd;
fd = open("myfile", O_RDWR | O_NONBLOCK, 0);
if(fd == -1) {
perror("open");
exit(1);
}
g->input = fdopen(fd, "r");
ev_io_init(&g->fifo_event, my_cb, fd, EV_READ);
ev_io_start(g->loop, &g->fifo_event);
}
void *crawler(void *threadid)
{
GlobalInfo g;
long tid;
tid = (long)threadid;
printf("Initalised thread #%ld!\n", tid);
memset(&g, 0, sizeof(GlobalInfo));
g.loop = ev_loop_new(EVFLAG_AUTO);
g.done = 0;
g.downloaded = 0;
g.head = 0;
g.added = 0;
g.concurrent_connections = 0;
init(&g);
g.multi = curl_multi_init();
ev_timer_init(&g.timer_event, timer_cb, 0., 0.);
g.timer_event.data = &g;
g.fifo_event.data = &g;
curl_multi_setopt(g.multi, CURLMOPT_SOCKETFUNCTION, sock_cb);
curl_multi_setopt(g.multi, CURLMOPT_SOCKETDATA, &g);
curl_multi_setopt(g.multi, CURLMOPT_TIMERFUNCTION, multi_timer_cb);
curl_multi_setopt(g.multi, CURLMOPT_TIMERDATA, &g);
/* we don't call any curl_multi_socket*() function yet as we have no handles
added! */
ev_loop(g.loop, 0);
curl_multi_cleanup(g.multi);
pthread_exit(NULL);
}
int main(int argc, char **argv)
{
(void)argc;
(void)argv;
mysql_start();
pthread_t threads[NUM_THREADS];
int rc;
long t;
for(t=0; t<NUM_THREADS; t++){
rc = pthread_create(&threads[t], NULL, crawler, (void *)t);
if (rc){
printf("ERROR; return code from pthread_create() is %d\n", rc);
exit(-1);
}
}
pthread_exit(NULL);
mysql_stop();
mysql_library_end();
return 0;
}
As you can see I attempt to make a new event loop in each thread with ev_loop_new. However, the program aborts with the following backtrace:
#0 __GI_raise (sig=sig#entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#1 0x00007ffff75bb859 in __GI_abort () at abort.c:79
#2 0x00007ffff76263ee in __libc_message (action=action#entry=do_abort, fmt=fmt#entry=0x7ffff7750285 "%s\n") at ../sysdeps/posix/libc_fatal.c:155
#3 0x00007ffff762e47c in malloc_printerr (str=str#entry=0x7ffff7752690 "double free or corruption (!prev)") at malloc.c:5347
#4 0x00007ffff763012c in _int_free (av=0x7ffff7781b80 <main_arena>, p=0x5555569ff1e0, have_lock=<optimized out>) at malloc.c:4317
#5 0x00007ffff79518c4 in ?? () from /lib/x86_64-linux-gnu/libmysqlclient.so.21
#6 0x00007ffff795215a in ?? () from /lib/x86_64-linux-gnu/libmysqlclient.so.21
#7 0x00007ffff78ffd0e in ?? () from /lib/x86_64-linux-gnu/libmysqlclient.so.21
#8 0x00007ffff78fffa5 in ?? () from /lib/x86_64-linux-gnu/libmysqlclient.so.21
#9 0x00007ffff7900155 in ?? () from /lib/x86_64-linux-gnu/libmysqlclient.so.21
#10 0x00007ffff7903795 in ?? () from /lib/x86_64-linux-gnu/libmysqlclient.so.21
#11 0x00007ffff7905804 in mysql_real_query_nonblocking () from /lib/x86_64-linux-gnu/libmysqlclient.so.21
#12 0x0000555555559a4e in add_url (g=0x7ffff6e71e50) at threads.c:1202
#13 0x000055555555a69b in my_cb (loop=0x7ffff0000f70, w=0x7ffff6e71e58, revents=1) at threads.c:1457
#14 0x00007ffff7810bc3 in ev_invoke_pending () from /lib/x86_64-linux-gnu/libev.so.4
#15 0x00007ffff7814b93 in ev_run () from /lib/x86_64-linux-gnu/libev.so.4
#16 0x0000555555556a73 in ev_loop (loop=0x7ffff0000f70, flags=0) at /usr/include/ev.h:842
#17 0x000055555555a990 in crawler (threadid=0x0) at threads.c:1517
#18 0x00007ffff78b1609 in start_thread (arg=<optimized out>) at pthread_create.c:477
#19 0x00007ffff76b8293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
(gdb) q
As you can see the offending line is ev_loop(g.loop, 0); which causes the abort. I thought I was doing the right thing with making a new event loop in each thread with ev_loop_new.
What am I doing wrong?