I believe the issue is between the profiler thread and the shutdown hook thread. Both will run concurrently because the profiler thread is marked deamon. So the shutdown hook thread can see the Profiler fields not fully initialized. The call to addShutdownHook() should be done outside of the Profiler constructor.
public static Profiler newInstance(Options options) {
Profiler profiler = new Profiler(options);
Runtime.getRuntime().addShutdownHook(new Thread(profiler::onEnd));
return profiler;
}
private Profiler(Options options) {
this.options = options;
this.store = new Store(options.getFlamePath());
}
public Profiler(Options options) {
this(options, null);
Runtime.getRuntime().addShutdownHook(new Thread(this::onEnd)); // okay to leak this here
}
private Profiler(Options options, Void dummy) {
this.options = options;
this.store = new Store(options.getFlamePath());
}