Package org.apache.storm.policy

Class WaitStrategyProgressive

java.lang.Object
org.apache.storm.policy.WaitStrategyProgressive
All Implemented Interfaces:
IWaitStrategy
public class WaitStrategyProgressive extends Object implements IWaitStrategy
A Progressive Wait Strategy.

Has three levels of idling. Stays in each level for a configured number of iterations before entering the next level. Level 1 - No idling. Returns immediately. Stays in this level for `level1Count` iterations. Level 2 - Calls LockSupport.parkNanos(1). Stays in this level for `level2Count` iterations Level 3 - Calls Thread.sleep(). Stays in this level until wait situation changes.

The initial spin can be useful to prevent downstream bolt from repeatedly sleeping/parking when the upstream component is a bit relatively slower. Allows downstream bolt can enter deeper wait states only if the traffic to it appears to have reduced.

  • Constructor Details

    • WaitStrategyProgressive

      public WaitStrategyProgressive()

  • Method Details

    • prepare

      public void prepare(Map<String,Object> conf, IWaitStrategy.WaitSituation waitSituation)
      Specified by:
      prepare in interface IWaitStrategy

    • idle

      public int idle(int idleCounter) throws InterruptedException
      Description copied from interface: IWaitStrategy
      Implementations of this method should be thread-safe (preferably no side-effects and lock-free).

      Supports static or dynamic backoff. Dynamic backoff relies on idleCounter to estimate how long caller has been idling. 

       
  int idleCounter = 0;
  int consumeCount = consumeFromQ();
  while (consumeCount==0) {
     idleCounter = strategy.idle(idleCounter);
     consumeCount = consumeFromQ();
  }
      Specified by:
      idle in interface IWaitStrategy
      Parameters:
      idleCounter - managed by the idle method until reset
      Returns:
      new counter value to be used on subsequent idle cycle
      Throws:
      InterruptedException