浅谈踩坑记之一个Java线程池参数，差点引起线上事故（上）

package org.apache.dubbo.common.threadpool.support.cached;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.common.threadlocal.NamedInternalThreadFactory;
import org.apache.dubbo.common.threadpool.ThreadPool;
import org.apache.dubbo.common.threadpool.support.AbortPolicyWithReport;
import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import static org.apache.dubbo.common.constants.CommonConstants.ALIVE_KEY;
import static org.apache.dubbo.common.constants.CommonConstants.CORE_THREADS_KEY;
import static org.apache.dubbo.common.constants.CommonConstants.DEFAULT_ALIVE;
import static org.apache.dubbo.common.constants.CommonConstants.DEFAULT_CORE_THREADS;
import static org.apache.dubbo.common.constants.CommonConstants.DEFAULT_QUEUES;
import static org.apache.dubbo.common.constants.CommonConstants.DEFAULT_THREAD_NAME;
import static org.apache.dubbo.common.constants.CommonConstants.QUEUES_KEY;
import static org.apache.dubbo.common.constants.CommonConstants.THREADS_KEY;
import static org.apache.dubbo.common.constants.CommonConstants.THREAD_NAME_KEY;
/**
 * This thread pool is self-tuned. Thread will be recycled after idle for one minute, and new thread will be created for
 * the upcoming request.
 *
 * @see java.util.concurrent.Executors#newCachedThreadPool()
 */
public class CachedThreadPool implements ThreadPool {
    @Override
    public Executor getExecutor(URL url) {
        //1 获取线程名称前缀 如果没有 默认是Dubbo
        String name = url.getParameter(THREAD_NAME_KEY, DEFAULT_THREAD_NAME);
        //2. 获取线程池核心线程数大小
        int cores = url.getParameter(CORE_THREADS_KEY, DEFAULT_CORE_THREADS);
        //3. 获取线程池最大线程数大小，默认整型最大值
        int threads = url.getParameter(THREADS_KEY, Integer.MAX_VALUE);
        //4. 获取线程池队列大小
        int queues = url.getParameter(QUEUES_KEY, DEFAULT_QUEUES);
        //5. 获取线程池多长时间被回收 单位毫秒
        int alive = url.getParameter(ALIVE_KEY, DEFAULT_ALIVE);
        //6. 使用JUC包里的ThreadPoolExecutor创建线程池
        return new ThreadPoolExecutor(cores, threads, alive, TimeUnit.MILLISECONDS,
                queues == 0 ? new SynchronousQueue<Runnable>() :
                        (queues < 0 ? new LinkedBlockingQueue<Runnable>()
                                : new LinkedBlockingQueue<Runnable>(queues)),
                new NamedInternalThreadFactory(name, true), new AbortPolicyWithReport(name, url));
    }
}

public ThreadPoolExecutor(int corePoolSize,
                              int maximumPoolSize,
                              long keepAliveTime,
                              TimeUnit unit,
                              BlockingQueue<Runnable> workQueue,
                              ThreadFactory threadFactory,
                              RejectedExecutionHandler handler) {
        if (corePoolSize < 0 ||
            maximumPoolSize <= 0 ||
            maximumPoolSize < corePoolSize ||
            keepAliveTime < 0)
            throw new IllegalArgumentException();
        if (workQueue == null || threadFactory == null || handler == null)
            throw new NullPointerException();
        this.acc = System.getSecurityManager() == null ?
                null :
                AccessController.getContext();
        this.corePoolSize = corePoolSize;
        this.maximumPoolSize = maximumPoolSize;
        this.workQueue = workQueue;
        this.keepAliveTime = unit.toNanos(keepAliveTime);
        this.threadFactory = threadFactory;
        this.handler = handler;
    }