segfault in spinOnce, what is wrong?

edit

I have nodes crashing short after launch, the console output is for example:

[JoggingNode-21] process has died [pid 29521, exit code -11

The problem only appears when I start the full system with 30+ nodes, not if I launch the single node.

The problem appears for different nodes for each launch.

The problem seems to be highly timing dependent and disappears if I launch the node with gdb or relaunch the crashed node while leaving the other nodes running.

I can printf debug the problem down to calling spinOnce.

Questions:

1. What is exit code -11 ?
2. Any way I can see in a log which callbacks ROS has been calling
3. Is combining spin and spinOnce a problem? I use it through out several nodes like shown below:

ROS node pseudo code:

void someCallback() {
    while (!ready) {
        spin_once();
    }
    ...
}
void someCallback2() {
     ready = true;
}

int main() {
    ...
    setupCallbacks();
    spin();
}

[EDIT]

Edited title. Also managed to get a core dump, here is the stack trace:

(gdb) bt
#0  0x00007fd568a88fac in std::deque<ros::CallbackQueue::CallbackInfo, std::allocator<ros::CallbackQueue::CallbackInfo> >::_M_erase(std::_Deque_iterator<ros::CallbackQueue::CallbackInfo, ros::CallbackQueue::CallbackInfo&, ros::CallbackQueue::CallbackInfo*>) () from /opt/ros/kinetic/lib/libroscpp.so
#1  0x00007fd568a85cc1 in ros::CallbackQueue::callOneCB(ros::CallbackQueue::TLS*) ()
   from /opt/ros/kinetic/lib/libroscpp.so
#2  0x00007fd568a870f3 in ros::CallbackQueue::callAvailable(ros::WallDuration) ()
   from /opt/ros/kinetic/lib/libroscpp.so
#3  0x00007fd568ac4795 in ros::spinOnce() () from /opt/ros/kinetic/lib/libroscpp.so