## Java 代码：
package com.zhuanzhuan.finance_mall.utils.parallel;

import com.zhuanzhuan.finance_mall.utils.parallel.dto.TaskGraph;
import com.zhuanzhuan.finance_mall.utils.parallel.dto.TaskNode;
import lombok.extern.slf4j.Slf4j;

import java.util.Collections;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 * 通用任务执行入口
 *
 * @Author youzhiqiang
 * @Date 2025-05-29 10:26
 */
@Slf4j
public class ParallelTaskEngine<T> {

    private final ExecutorService executor;
    private final TaskGraph<T> taskGraph;

    public ParallelTaskEngine(ExecutorService executor, TaskGraph<T> taskGraph) {
        this.executor = executor;
        this.taskGraph = taskGraph;
    }

    public void execute(T context, long timeoutMillis) throws Exception {
        // 存储所有任务的执行Future，用于后续等待任务完成
        Map<String, Future<Void>> futures = new ConcurrentHashMap<>();
        // 存储每个任务的计数器，用于同步任务的依赖完成情况
        Map<String, CountDownLatch> latchMap = new ConcurrentHashMap<>();
        // 存储任务开始时间
        Map<String, Long> taskStartTimes = new ConcurrentHashMap<>();

        // 初始化每个任务的计数器
        taskGraph.getDependencyCounts().forEach((name, count) ->
                latchMap.put(name, new CountDownLatch(count)));

        // 遍历所有任务，提交任务到线程池执行
        for (String taskName : taskGraph.getTaskMap().keySet()) {
            futures.put(taskName, executor.submit(() -> {
                TaskNode<T> node = taskGraph.getTaskMap().get(taskName);
                CountDownLatch latch = latchMap.get(taskName);

                try {
                    doRunTaskLogics(context, taskName, latch, node, taskStartTimes);
                } finally {
                    // 通知依赖此任务的其他任务
                    taskGraph.getReverseDeps().getOrDefault(taskName, Collections.emptyList())
                            .forEach(dep -> latchMap.get(dep).countDown());
                }
                return null;
            }));
        }

        // 等待所有任务完成或超时
        try {
            for (Future<Void> future : futures.values()) {
                future.get(timeoutMillis, TimeUnit.MILLISECONDS);
            }
        } catch (TimeoutException e) {
            // 取消所有未完成的任务
            futures.values().forEach(future -> future.cancel(true));
            throw e;
        }
    }

    private static <T> void doRunTaskLogics(T context, String taskName, CountDownLatch latch, TaskNode<T> node, Map<String, Long> taskStartTimes) throws TimeoutException, InterruptedException {
        // 记录等待依赖任务的时间
        long waitStartTime = System.currentTimeMillis();
        try {
            boolean awaitResult = latch.await(node.waitTimeoutMillis, TimeUnit.MILLISECONDS);
            if (!awaitResult) {
                throw new TimeoutException("Task " + taskName + " timed out waiting for dependencies");
            }
        } catch (InterruptedException e) {
            log.error("ParallelTaskEngine taskName={} interrupted while waiting for dependencies", taskName, e);
            Thread.currentThread().interrupt();
            throw e;
        }
        long waitTime = System.currentTimeMillis() - waitStartTime;

        // 记录任务开始时间
        taskStartTimes.put(taskName, System.currentTimeMillis());

        // 先执行主任务逻辑
        try {
            log.info("ParallelTaskEngine taskName={} begin.", taskName);
            node.logic.run(context);
        } catch (Exception e) {
            log.error("ParallelTaskEngine taskName={} error. {}", taskName, node.fallback != null ? "has fallback" : "", e);
            // 如果存在降级方法，尝试执行降级逻辑
            if (node.fallback != null) {
                try {
                    node.fallback.accept(context);
                } catch (Exception fallbackError) {
                    log.error("ParallelTaskEngine taskName={} fallback Task run failed!", taskName, fallbackError);
                    throw e;
                }
            } else {
                throw e;
            }
        }

        // 计算任务执行时间
        long taskEndTime = System.currentTimeMillis();
        long taskStartTime = taskStartTimes.get(taskName);
        long taskExecutionTime = taskEndTime - taskStartTime;

        // 记录任务执行耗时
        log.info("ParallelTaskEngine taskName={} completed. waitTime={}ms, executionTime={}ms, totalTime={}ms",
                taskName, waitTime, taskExecutionTime, waitTime + taskExecutionTime);
    }
}


指出以上Java代码存在哪些问题？若在工程中使用有哪些可以优化的空间？（使用中文回答）