subprojects/parseq/src/main/java/com/linkedin/parseq/Engine.java
private boolean tryAcquirePermit(String planClass) {
    return _concurrentPlans.tryAcquire() &&
        (_planBasedRateLimiter == null || _planBasedRateLimiter.tryAcquire(planClass));
  }
private boolean tryAcquirePermit(String planClass) {
    return _concurrentPlans.tryAcquire() &&
        (_planBasedRateLimiter == null || _planBasedRateLimiter.tryAcquire(planClass));
  }
rate limiter and then from plan class level rate limit if specified.