Java Springboot ThreadPoolTaskExecuter

# Error troubleshooting java thread pool

# Device

1. arm64 macOS

# Environment

• Java corretto-17
• Springboot 3.0.2

# Problem

• Problem description
  I have a problem when using Springboot ThreadPoolTaskExecutor . The code below looks like this:

// create operation

var finalGroup = group;

var path = getGroupParentPath(finalGroup.getId());

var sourcePath = finalGroup.getSourceId()+"/"+path;

var event = new ChokidarEvent().setEvent(ChangeType.addDir).setPath(

  sourcePath

);

threadPoolTaskExecutor.submit(() -> {

  sendChokidarEvent(finalGroup.getSourceId(), event);

});

• Porblem reproduce
  The sendChokidarEvent create function is blocking when the code waits for the completion of the get function on the Future . But while another delete function is running, the code is continuing to run.

threadPoolTaskExecutor.submit(new Thread(()->{

  if (subscribers.containsKey(finalGroup.getSourceId())) {

    var path = getGroupParentPath(finalGroup.getParent());

    var sourcePath = finalGroups.get(0).getSourceId() + "/" + path + "/" + id;

    if (!StringUtils.hasText(path)){

        sourcePath = finalGroups.get(0).getSourceId() + "/" + id;

    }

    sendChokidarEvent(finalGroup.getSourceId(), new ChokidarEvent().setEvent(ChangeType.unlinkDir).setPath(sourcePath));

  }

}));

• Test result
  When testing with POSTMAN, it can be observed that the unlinkDir event is being sent before the addDir event in the output of the SseEmitter.

# Knowledge

ThreadPoolTaskExecutor utilizes a blocking queue approach, and due to a certain condition, the addDir function sendChokidarEvent is continuously blocked.

# Solution

0. No similar issue has been found in the existing online resources.
1. Inspecting the source code.

After examining the source code, it becomes evident that ThreadPoolTaskExecutor is merely a wrapper around ThreadPoolExecutor . Furthermore, upon inspecting ThreadPoolExecutor , it can be observed that there is no actively blocking code within it. However, after setting another breakpoint and further analysis, it was discovered that the reason for breakpoints disappearing in subsequent code segments is due to the getGroupParentPath function.

# Solved

This issue is a basic mistake, caused by a typo in the variable within getGroupParentPath , resulting in an infinite loop and preventing the execution of subsequent code.