[GitHub] [rocketmq] yihleego opened a new issue, #4654: [OPTIMIZATION] Reduce unnecessary DeliverDelayedMessageTimerTask and HandlePutResultTask object creation

[GitBox <gi...@apache.org>]

yihleego opened a new issue, #4654:
URL: https://github.com/apache/rocketmq/issues/4654

   When starting a broker instance with the default configuration, the `ScheduleMessageService` will create 180 `DeliverDelayedMessageTimerTask` objects per second, and 1800 `HandlePutResultTask` objects per second if `enableAsyncDeliver` is `true`, which is **NOT** good for GC.
   
   Let's see some code:
   
   ```java
   public class MessageStoreConfig {
       // By default, there are 18 levels.
       private String messageDelayLevel = "1s 5s 10s 30s 1m 2m 3m 4m 5m 6m 7m 8m 9m 10m 20m 30m 1h 2h";
   }
   ```
   
   [ScheduleMessageService#start](https://github.com/apache/rocketmq/blob/00da3e7249d2339717d96f7ea2ab8e4a2fd4242c/broker/src/main/java/org/apache/rocketmq/broker/schedule/ScheduleMessageService.java#L141)
   
   
   ```java
   private static final long FIRST_DELAY_TIME = 1000L;
   private static final long DELAY_FOR_A_WHILE = 100L;
   private static final long DELAY_FOR_A_PERIOD = 10000L;
   private static final long WAIT_FOR_SHUTDOWN = 5000L;
   private static final long DELAY_FOR_A_SLEEP = 10L;
   
   public void start() {
       if (started.compareAndSet(false, true)) {
           // ignore
   
           for (Map.Entry<Integer, Long> entry : this.delayLevelTable.entrySet()) {
               Integer level = entry.getKey();
               Long timeDelay = entry.getValue();
               Long offset = this.offsetTable.get(level);
               if (null == offset) {
                   offset = 0L;
               }
               if (timeDelay != null) {
                   if (this.enableAsyncDeliver) {
                   	// Create a HandlePutResultTask object for each level if enableAsyncDeliver is true.
                       this.handleExecutorService.schedule(new HandlePutResultTask(level), FIRST_DELAY_TIME, TimeUnit.MILLISECONDS);
                   }
                   // Create a DeliverDelayedMessageTimerTask object for each level.
                   this.deliverExecutorService.schedule(new DeliverDelayedMessageTimerTask(level, offset), FIRST_DELAY_TIME, TimeUnit.MILLISECONDS);
               }
           }
   
           // ignore
       }
   }
   ```
   
   [ScheduleMessageService#DeliverDelayedMessageTimerTask](https://github.com/apache/rocketmq/blob/00da3e7249d2339717d96f7ea2ab8e4a2fd4242c/broker/src/main/java/org/apache/rocketmq/broker/schedule/ScheduleMessageService.java#L383)
   
   ```java
   class DeliverDelayedMessageTimerTask implements Runnable {
       @Override
       public void run() {
           try {
               if (isStarted()) {
                   this.executeOnTimeup();
               }
           } catch (Exception e) {
               // XXX: warn and notify me
               log.error("ScheduleMessageService, executeOnTimeup exception", e);
               this.scheduleNextTimerTask(this.offset, DELAY_FOR_A_PERIOD);
           }
       }
   
       public void executeOnTimeup() {
           // ignore
   
           // At the end of execution, a new DeliverDelayedMessageTimerTask object will be created, and it will run after 100ms.
           this.scheduleNextTimerTask(nextOffset, DELAY_FOR_A_WHILE);
       }
   
       public void scheduleNextTimerTask(long offset, long delay) {
           ScheduleMessageService.this.deliverExecutorService.schedule(new DeliverDelayedMessageTimerTask(
               this.delayLevel, offset), delay, TimeUnit.MILLISECONDS);
       }
   }
   ```
   
   [ScheduleMessageService#HandlePutResultTask](https://github.com/apache/rocketmq/blob/00da3e7249d2339717d96f7ea2ab8e4a2fd4242c/broker/src/main/java/org/apache/rocketmq/broker/schedule/ScheduleMessageService.java#L569)
   
   ```java
   public class HandlePutResultTask implements Runnable {
       @Override
       public void run() {
           // ignore
   
           // At the end of execution, a new HandlePutResultTask object will be created, and it will run after 10ms.
           if (isStarted()) {
               ScheduleMessageService.this.handleExecutorService
                   .schedule(new HandlePutResultTask(this.delayLevel), DELAY_FOR_A_SLEEP, TimeUnit.MILLISECONDS);
           }
       }
   }
   ```
   
   ---
   
   So, it's better to use `ScheduledExecutorService#scheduleWithFixedDelay` instead of creating unnecessary objects.
   


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[GitHub] [rocketmq] yihleego closed issue #4654: [OPTIMIZATION] Reduce unnecessary DeliverDelayedMessageTimerTask and HandlePutResultTask object creation

["yihleego (via GitHub)" <gi...@apache.org>]

yihleego closed issue #4654: [OPTIMIZATION] Reduce unnecessary DeliverDelayedMessageTimerTask and HandlePutResultTask object creation
URL: https://github.com/apache/rocketmq/issues/4654


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