Avoiding cache stampede at DoorDash

 

https://medium.com/@DoorDash/avoiding-cache-stampede-at-doordash-55bbf596d94b

Avoiding cache stampede at DoorDash

 

DoorDash Cache 전략.

 

A typical caching setup

The debouncer approach

To solve the problem, we took inspiration from something front-end engineers use frequently. Debouncing is a common practice in the JS world to prevent duplicate events from firing and causing noise in the system. A well-known way to create a debouncing function looks something like this (using lodash or underscore.js):

 

https://github.com/syesildag/debounce/blob/master/src/main/java/debounce/DebounceExecutor.java

GitHub - syesildag/debounce

 

import java.util.concurrent.Callable;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;

import java.lang.Thread;

public class DebounceExecutor
{
   private ScheduledExecutorService executor;
   private ScheduledFuture<Object> future;
   
   public DebounceExecutor()
   {
      this.executor = Executors.newSingleThreadScheduledExecutor(new ThreadFactory()
      {
         @Override
         public Thread newThread(Runnable r)
         {
            Thread t = new Thread(r, "Debouncer");
            t.setDaemon(true);
            return t;
         }
      });
   }
   
   public ScheduledFuture<Object> debounce(long delay, Callable<Object> task)
   {
      if (this.future != null && !this.future.isDone())
         this.future.cancel(false);
      
      return this.future = this.executor.schedule(task, delay, TimeUnit.MILLISECONDS);
   }
}