Boost condition variables

[helios]

template <typename T>
class Event{
	bool ready;
	T var;
	boost::condition_variable cv;
	boost::mutex mutex;
public:
	Event():ready(0){}
	void set(const T &var){
		boost::unique_lock<boost::mutex> lock(this->mutex);
		this->var=var;
		this->ready=1;
#if NOTIFY_ONE
		this->cv.notify_one();
#else
		this->cv.notify_all();
#endif
	}
	const T &wait(){
		boost::unique_lock<boost::mutex> lock(this->mutex);
		while (!this->ready)
			this->cv.wait(lock);
		this->ready=0;
		return this->var;
	}
};

void PooledThread::running_thread(void *p){
	PooledThread *_this=(PooledThread *)p;
	while (_this->start_call_event.wait()){
		_this->function(_this->parameter);
		_this->parameter=0;
		_this->function=0;
		_this->call_ended_event.set(1);
	}
}

void PooledThread::operator()(threaded_function_t f,void *p){
	this->function=f;
	this->parameter=p;
	this->start_call_event.set(1);
}

void PooledThread::join(){
	this->call_ended_event.wait();
}

If !NOTIFY_ONE, the program behaves nicely. Otherwise, I see the CPU usage increase linearly over time (running_thread gets a new job at frequent regular intervals).
Why could this be?