前言
这篇是推动大家异步编程的思想的线程池的准备篇，要做好监控，让大家使用无后顾之忧，敬畏生产。
为什么需要对线程池进行监控
Java线程池作为最常使用到的并发工具，相信大家都不陌生，但是你真的确定使用对了吗？大名鼎鼎的阿里Java代码规范要求我们不使用 Executors来快速创建线程池，但是抛弃Executors，使用其它方式创建线程池就一定不会出现问题吗？本质上对于我们来说线程池本身的运行过程是一个黑盒，我们没办法了解线程池中的运行状态时，出现问题没有办法及时判断和预警。面对这种黑盒操作必须通过监控方式让其透明化，这样对我们来说才能更好的使用好线程池。因此必须对线程池做监控。
image.png
如何做线程池的监控
对于如何做监控，本质就是涉及三点，分别是数据采集、数据存储以及大盘的展示，接下来我们分说下这三点；
数据采集
采集什么数据，对于我们来说需要采集就是黑盒的数据，什么又是线程池的黑盒数据，其实也就是整个线程处理的整个流程，在整个流程中，我们可以通过ThreadPoolExecutor中的七个方法获取数据，通过这七个方法采集到的数据就可以使线程池的执行过程透明化。
- getCorePoolSize()：获取核心线程数；
- getMaximumPoolSize：获取最大线程数；
- getQueue()：获取线程池中的阻塞队列，并通过阻塞队列中的方法获取队列长度、元素个数等；
- getPoolSize()：获取线程池中的工作线程数（包括核心线程和非核心线程）；
- getActiveCount()：获取活跃线程数，也就是正在执行任务的线程；
- getLargestPoolSize()：获取线程池曾经到过的最大工作线程数；
- getTaskCount()：获取历史已完成以及正在执行的总的任务数量；
除了我们了解的这些流程以外，ThreadPoolExecutor中还提供了三种钩子函数，
- beforeExecute()：Worker线程执行任务之前会调用的方法；
- afterExecute()：在Worker线程执行任务之后会调用的方法；
- terminated()：当线程池从运行状态变更到TERMINATED状态之前调用的方法;
对于beforeExecute和afterExecute可以理解为使用Aop监听线程执行的时间，这样子我们可以对每个线程运行的时间整体做监控，terminated可以理解为线程关闭时候的监控，这样我们就可以整体获取采集到线程池生命周期的所有数据了。
数据存储以及大盘的展示
对于存储我们这个比较适合采用时序性数据库，此外现在很多成熟的监控产品都可以满足我们大屏展示的诉求，这里推荐下美团Cat和Prometheus，这里不展开进行讲解，大家可以根据自己公司的监控产品进行选择，对于不同的方案采取的存储形式会有些差异，甚至自己都可以自定义实现一个功能，反正难度不大。
进一步扩展以及思考
在实际的项目开发中我们会遇到以下场景:
- 不同的业务采用同一个线程池，这样如果某个服务阻塞，会影响到整体共用线程池的所有服务，会触发线程池的拒绝策略；
- 流量突然增加，需要动态调整线程池的参数，这个时候又不能重启；
针对这两种场景，我们对线程池再次进行了深入的思考:
- 如何合理配置线程池参数；
- 如何动态调整线程池参数；
- 如何给不同的服务之间做线程池的隔离；
如何合理配置线程池参数
关于这个问题面试的时候也是经常被问到，我只能说这个问题开始就是一个坑，针对与CPU密集型和I/O密集型，线程池的参数是有不同设计的，也不是遵守几个公式就可以搞定，当然可以参考，我认为对于线程池合理的参数的配置是经过多次调整得到的，甚至增加和减少业务都会影响一些参数，我不太建议大家每天背书式的CPU密集型就是N+1，非CPU密集型就是2N，因此我们更希望看到线程池动态配置。
如何动态调整线程池参数
关于如何动态调整线程池，还是回到我们场景问题的解决上，对于流量突增核心就是提升线程池的处理速度，那如何提升线程池的处理速度，有两种方式，一种是加快业务的处理，也就是消费的快，显然这种在运行的业务中我们想改变还是比较困难，这个可以作为复盘的重点；还有一种就是增加消费者，增加消费者的重点就是调整核心线程数以及非核心线程数的数量。
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居于这种思考，这个时候我们需要看下ThreadPoolExecutor线程池源码，首先看下开始定义的变量，通过变量的设计我们就会发现大师就是大师，大师通过AtomicInteger修饰的ctl变量，高3位存储了线程池的状态，低29存储线程的个数，通过一个变量完成两件事情，完成状态判断以及限制线程最大个数。使用一个HashSet存储Worker的引用，而Worker继承了AbstractQueuedSynchronizer，实现一个一个不可冲入的独占锁保证线程的安全性。
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//用来标记线程池状态（高3位），线程个数（低29位）
private final AtomicInteger ctl = new AtomicInteger(ctlOf(RUNNING, 0));
//工作状态存储在高3位中
private static final int COUNT_BITS = Integer.SIZE - 3;
//线程个数所能表达的最大数值
private static final int CAPACITY = (1 << COUNT_BITS) - 1;
//线程池状态
//RUNNING -1 能够接收新任务，也可以处理阻塞队列中的任务
private static final int RUNNING = -1 << COUNT_BITS;
//SHUTDOWN 0 不可以接受新任务，继续处理阻塞队列中的任务
private static final int SHUTDOWN = 0 << COUNT_BITS;
//STOP 1 不接收新任务，不处理阻塞队列中的任务，并且会中断正在处理的任务
private static final int STOP = 1 << COUNT_BITS;
//TIDYING 2 所有任务已经中止，且工作线程数量为0，最后变迁到这个状态的线程将要执行terminated()钩子方法，只会有一个线程执行这个方法；
private static final int TIDYING = 2 << COUNT_BITS;
//TERMINATED 3 中止状态，已经执行完terminated()钩子方法
private static final int TERMINATED = 3 << COUNT_BITS;
//任务队列，当线程池中的线程达到核心线程数量时，再提交任务 就会直接提交到 workQueue
private final BlockingQueue workQueue;
//线程池全局锁，增加worker减少worker时需要持有mainLock，修改线程池运行状态时，也需要
private final ReentrantLock mainLock = new ReentrantLock();
//线程池中真正存放worker的地方。
private final HashSet workers = new HashSet();
private final Condition termination = mainLock.newCondition();
//记录线程池生命周期内 线程数最大值
private int largestPoolSize;
//记录线程池所完成任务总数
private long completedTaskCount;
//创建线程会使用线程工厂
private volatile ThreadFactory threadFactory;
//拒绝策略
private volatile RejectedExecutionHandler handler;
//存活时间
private volatile long keepAliveTime;
//控制核心线程数量内的线程 是否可以被回收。true 可以，false不可以。
private volatile boolean allowCoreThreadTimeOut;
//核心线程池数量
private volatile int corePoolSize;
//线程池最大数量
private volatile int maximumPoolSize;
我们的重点看的是volatile修饰的corePoolSize、maximumPoolSize以及keepAliveTime，当然threadFactory和handler也可以看下，不过这两个不是我们解决动态调整线程池的关键。对于这些volatile修饰的关键的变量，从并发角度思考的，必然是有并发读写的操作才使用volatile修饰的，在指标采集中我们看到其get的方法，对于写的操作我们可以猜测肯定提供了set的方式，这个时候我们可以搜索下setCorePoolSize，果不其然我们真的搜索到了。
public void setCorePoolSize(int corePoolSize) {
if (corePoolSize < 0)
throw new IllegalArgumentException();
int delta = corePoolSize - this.corePoolSize;
this.corePoolSize = corePoolSize;
//新设置的corePoolSize小于当前核心线程数的时候
//会调用interruptIdleWorkers方法来中断空闲的工作线程
if (workerCountOf(ctl.get()) > corePoolSize)
interruptIdleWorkers();
else if (delta > 0) {
//当设置的值大于当前值的时候核心线程数的时候
//按照等待队列中的任务数量来创建新的工作线程
int k = Math.min(delta, workQueue.size());
while (k-- > 0 && addWorker(null, true)) {
if (workQueue.isEmpty())
break;
}
}
}
接下来我们看下interruptIdleWorkers的源码，此处源码使用ReentrantLock可重入锁，因为Worker的是通过一个全局的HashSer存储，这里通过ReentrantLock保证线程安全。
private void interruptIdleWorkers(boolean onlyOne) {
//可重入锁
final ReentrantLock mainLock = this.mainLock;
mainLock.lock();
try {
for (Worker w : workers) {
Thread t = w.thread;
if (!t.isInterrupted() && w.tryLock()) {
try {
//中断当前线程
t.interrupt();
} catch (SecurityException ignore) {
} finally {
w.unlock();
}
}
if (onlyOne)
break;
}
} finally {
mainLock.unlock();
}
}
接下来我们在验证一下是否存在其他相关的参数设置，如下：
public void setMaximumPoolSize(int maximumPoolSize) {
if (maximumPoolSize <= 0 || maximumPoolSize < corePoolSize)
throw new IllegalArgumentException();
this.maximumPoolSize = maximumPoolSize;
if (workerCountOf(ctl.get()) > maximumPoolSize)
interruptIdleWorkers();
}
public void setKeepAliveTime(long time, TimeUnit unit) {
if (time < 0)
throw new IllegalArgumentException();
if (time == 0 && allowsCoreThreadTimeOut())
throw new IllegalArgumentException("Core threads must have nonzero keep alive times");
long keepAliveTime = unit.toNanos(time);
long delta = keepAliveTime - this.keepAliveTime;
this.keepAliveTime = keepAliveTime;
if (delta < 0)
interruptIdleWorkers();
}
public void setRejectedExecutionHandler(RejectedExecutionHandler handler) {
if (handler == null)
throw new NullPointerException();
this.handler = handler;
}
这里我们会发现一个问题BlockingQueue的队列容量不能修改，看到美团的文章提供的一个可修改的队列ResizableCapacityLinkedBlockingQueue，于是乎去看了一下LinkedBlockingQueue的源码，发现了关于capacity是一个final修饰的，这个时候我就思考一番，这个地方采用volatile修饰，对外暴露可修改，这样就实现了动态修改阻塞队列的大小。
img
如何给不同的服务之间做线程池的隔离
img
关于如何给不同服务之间做线程池的隔离，这里我们可以采用Hystrix的舱壁模式，也就是说针对不同服务类型的服务单独创建线程池，这样就可以实现服务之间不相互影响，不会因为某个服务导致整体的服务影响都阻塞。
实现方案
聊了这么多前置的知识储备，接下来我们来聊聊实现方案，整体的实现方案我们建立在Spring Boot的基础实现，采用Spring Cloud刷新动态配置，采用该方式比较合适单体应用，对于有Appllo和Nacos可以通过监听配置方式的来动态刷新。
- Maven依赖如下；
org.springframework.boot
spring-boot-starter
org.springframework.boot
spring-boot-starter-web
org.springframework.cloud
spring-cloud-context
org.springframework.boot
spring-boot-starter-test
test
org.projectlombok
lombok
1.18.12
org.slf4j
slf4j-api
1.7.5
ch.qos.logback
logback-core
1.2.3
ch.qos.logback
logback-classic
1.2.3
org.springframework.cloud
spring-cloud-dependencies
Hoxton.SR7
pom
import
- 配置信息如下:
monitor.threadpool.executors[0].thread-pool-name=first-monitor-thread-pool
monitor.threadpool.executors[0].core-pool-size=4
monitor.threadpool.executors[0].max-pool-size=8
monitor.threadpool.executors[0].queue-capacity=100
monitor.threadpool.executors[1].thread-pool-name=second-monitor-thread-pool
monitor.threadpool.executors[1].core-pool-size=2
monitor.threadpool.executors[1].max-pool-size=4
monitor.threadpool.executors[1].queue-capacity=40
/**
* 线程池配置
*
* @author wangtongzhou
* @since 2022-03-11 21:41
*/
@Data
public class ThreadPoolProperties {
/**
* 线程池名称
*/
private String threadPoolName;
/**
* 核心线程数
*/
private Integer corePoolSize = Runtime.getRuntime().availableProcessors();
/**
* 最大线程数
*/
private Integer maxPoolSize;
/**
* 队列最大数量
*/
private Integer queueCapacity;
/**
* 拒绝策略
*/
private String rejectedExecutionType = "AbortPolicy";
/**
* 空闲线程存活时间
*/
private Long keepAliveTime = 1L;
/**
* 空闲线程存活时间单位
*/
private TimeUnit unit = TimeUnit.MILLISECONDS;
}
/**
* 动态刷新线程池配置
*
* @author wangtongzhou
* @since 2022-03-13 14:09
*/
@ConfigurationProperties(prefix = "monitor.threadpool")
@Data
@Component
public class DynamicThreadPoolProperties {
private List executors;
}
- 自定可修改阻塞队列大小的方式如下:
/**
* 可重新设定队列大小的阻塞队列
*
* @author wangtongzhou
* @since 2022-03-13 11:54
*/
public class ResizableCapacityLinkedBlockingQueue<E> extends AbstractQueue<E>
implements BlockingDeque<E>, java.io.Serializable {
/*
* Implemented as a simple doubly-linked list protected by a
* single lock and using conditions to manage blocking.
*
* To implement weakly consistent iterators, it appears we need to
* keep all Nodes GC-reachable from a predecessor dequeued Node.
* That would cause two problems:
* - allow a rogue Iterator to cause unbounded memory retention
* - cause cross-generational linking of old Nodes to new Nodes if
* a Node was tenured while live, which generational GCs have a
* hard time dealing with, causing repeated major collections.
* However, only non-deleted Nodes need to be reachable from
* dequeued Nodes, and reachability does not necessarily have to
* be of the kind understood by the GC. We use the trick of
* linking a Node that has just been dequeued to itself. Such a
* self-link implicitly means to jump to "first" (for next links)
* or "last" (for prev links).
*/
/*
* We have "diamond" multiple interface/abstract class inheritance
* here, and that introduces ambiguities. Often we want the
* BlockingDeque javadoc combined with the AbstractQueue
* implementation, so a lot of method specs are duplicated here.
*/
private static final long serialVersionUID = -387911632671998426L;
/**
* Doubly-linked list node class
*/
static final class Node<E> {
/**
* The item, or null if this node has been removed.
*/
E item;
/**
* One of:
* - the real predecessor Node
* - this Node, meaning the predecessor is tail
* - null, meaning there is no predecessor
*/
Node prev;
/**
* One of:
* - the real successor Node
* - this Node, meaning the successor is head
* - null, meaning there is no successor
*/
Node next;
Node(E x) {
item = x;
}
}
/**
* Pointer to first node.
* Invariant: (first == null && last == null) ||
* (first.prev == null && first.item != null)
*/
transient Node first;
/**
* Pointer to last node.
* Invariant: (first == null && last == null) ||
* (last.next == null && last.item != null)
*/
transient Node last;
/**
* Number of items in the deque
*/
private transient int count;
/**
* Maximum number of items in the deque
*/
private volatile int capacity;
public int getCapacity() {
return capacity;
}
public void setCapacity(int capacity) {
this.capacity = capacity;
}
/**
* Main lock guarding all access
*/
final ReentrantLock lock = new ReentrantLock();
/**
* Condition for waiting takes
*/
private final Condition notEmpty = lock.newCondition();
/**
* Condition for waiting puts
*/
private final Condition notFull = lock.newCondition();
/**
* Creates a {@code ResizableCapacityLinkedBlockIngQueue} with a capacity of
* {@link Integer#MAX_VALUE}.
*/
public ResizableCapacityLinkedBlockingQueue() {
this(Integer.MAX_VALUE);
}
/**
* Creates a {@code ResizableCapacityLinkedBlockIngQueue} with the given (fixed) capacity.
*
* @param capacity the capacity of this deque
* @throws IllegalArgumentException if {@code capacity} is less than 1
*/
public ResizableCapacityLinkedBlockingQueue(int capacity) {
if (capacity <= 0) {
throw new IllegalArgumentException();
}
this.capacity = capacity;
}
/**
* Creates a {@code ResizableCapacityLinkedBlockIngQueue} with a capacity of
* {@link Integer#MAX_VALUE}, initially containing the elements of
* the given collection, added in traversal order of the
* collection's iterator.
*
* @param c the collection of elements to initially contain
* @throws NullPointerException if the specified collection or any
* of its elements are null
*/
public ResizableCapacityLinkedBlockingQueue(Collection c) {
this(Integer.MAX_VALUE);
final ReentrantLock lock = this.lock;
lock.lock(); // Never contended, but necessary for visibility
try {
for (E e : c) {
if (e == null) {
throw new NullPointerException();
}
if (!linkLast(new Node(e))) {
throw new IllegalStateException("Deque full");
}
}
} finally {
lock.unlock();
}
}
// Basic linking and unlinking operations, called only while holding lock
/**
* Links node as first element, or returns false if full.
*/
private boolean linkFirst(Node node) {
// assert lock.isHeldByCurrentThread();
if (count >= capacity) {
return false;
}
Node f = first;
node.next = f;
first = node;
if (last == null) {
last = node;
} else {
f.prev = node;
}
++count;
notEmpty.signal();
return true;
}
/**
* Links node as last element, or returns false if full.
*/
private boolean linkLast(Node node) {
// assert lock.isHeldByCurrentThread();
if (count >= capacity) {
return false;
}
Node l = last;
node.prev = l;
last = node;
if (first == null) {
first = node;
} else {
l.next = node;
}
++count;
notEmpty.signal();
return true;
}
/**
* Removes and returns first element, or null if empty.
*/
private E unlinkFirst() {
// assert lock.isHeldByCurrentThread();
Node f = first;
if (f == null) {
return null;
}
Node n = f.next;
E item = f.item;
f.item = null;
f.next = f; // help GC
first = n;
if (n == null) {
last = null;
} else {
n.prev = null;
}
--count;
notFull.signal();
return item;
}
/**
* Removes and returns last element, or null if empty.
*/
private E unlinkLast() {
// assert lock.isHeldByCurrentThread();
Node l = last;
if (l == null) {
return null;
}
Node p = l.prev;
E item = l.item;
l.item = null;
l.prev = l; // help GC
last = p;
if (p == null) {
first = null;
} else {
p.next = null;
}
--count;
notFull.signal();
return item;
}
/**
* Unlinks x.
*/
void unlink(Node x) {
// assert lock.isHeldByCurrentThread();
Node p = x.prev;
Node n = x.next;
if (p == null) {
unlinkFirst();
} else if (n == null) {
unlinkLast();
} else {
p.next = n;
n.prev = p;
x.item = null;
// Don't mess with x's links. They may still be in use by
// an iterator.
--count;
notFull.signal();
}
}
// BlockingDeque methods
/**
* @throws IllegalStateException if this deque is full
* @throws NullPointerException {@inheritDoc}
*/
@Override
public void addFirst(E e) {
if (!offerFirst(e)) {
throw new IllegalStateException("Deque full");
}
}
/**
* @throws IllegalStateException if this deque is full
* @throws NullPointerException {@inheritDoc}
*/
@Override
public void addLast(E e) {
if (!offerLast(e)) {
throw new IllegalStateException("Deque full");
}
}
/**
* @throws NullPointerException {@inheritDoc}
*/
@Override
public boolean offerFirst(E e) {
if (e == null) {
throw new NullPointerException();
}
Node node = new Node(e);
final ReentrantLock lock = this.lock;
lock.lock();
try {
return linkFirst(node);
} finally {
lock.unlock();
}
}
/**
* @throws NullPointerException {@inheritDoc}
*/
@Override
public boolean offerLast(E e) {
if (e == null) throw new NullPointerException();
Node node = new Node(e);
final ReentrantLock lock = this.lock;
lock.lock();
try {
return linkLast(node);
} finally {
lock.unlock();
}
}
/**
* @throws NullPointerException {@inheritDoc}
* @throws InterruptedException {@inheritDoc}
*/
@Override
public void putFirst(E e) throws InterruptedException {
if (e == null) {
throw new NullPointerException();
}
Node node = new Node(e);
final ReentrantLock lock = this.lock;
lock.lock();
try {
while (!linkFirst(node)) {
notFull.await();
}
} finally {
lock.unlock();
}
}
/**
* @throws NullPointerException {@inheritDoc}
* @throws InterruptedException {@inheritDoc}
*/
@Override
public void putLast(E e) throws InterruptedException {
if (e == null) {
throw new NullPointerException();
}
Node node = new Node(e);
final ReentrantLock lock = this.lock;
lock.lock();
try {
while (!linkLast(node)) {
notFull.await();
}
} finally {
lock.unlock();
}
}
/**
* @throws NullPointerException {@inheritDoc}
* @throws InterruptedException {@inheritDoc}
*/
@Override
public boolean offerFirst(E e, long timeout, TimeUnit unit)
throws InterruptedException {
if (e == null) {
throw new NullPointerException();
}
Node node = new Node(e);
long nanos = unit.toNanos(timeout);
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
while (!linkFirst(node)) {
if (nanos <= 0) {
return false;
}
nanos = notFull.awaitNanos(nanos);
}
return true;
} finally {
lock.unlock();
}
}
/**
* @throws NullPointerException {@inheritDoc}
* @throws InterruptedException {@inheritDoc}
*/
@Override
public boolean offerLast(E e, long timeout, TimeUnit unit)
throws InterruptedException {
if (e == null) throw new NullPointerException();
Node node = new Node(e);
long nanos = unit.toNanos(timeout);
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
while (!linkLast(node)) {
if (nanos <= 0) {
return false;
}
nanos = notFull.awaitNanos(nanos);
}
return true;
} finally {
lock.unlock();
}
}
/**
* @throws NoSuchElementException {@inheritDoc}
*/
@Override
public E removeFirst() {
E x = pollFirst();
if (x == null) {
throw new NoSuchElementException();
}
return x;
}
/**
* @throws NoSuchElementException {@inheritDoc}
*/
@Override
public E removeLast() {
E x = pollLast();
if (x == null) {
throw new NoSuchElementException();
}
return x;
}
@Override
public E pollFirst() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return unlinkFirst();
} finally {
lock.unlock();
}
}
@Override
public E pollLast() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return unlinkLast();
} finally {
lock.unlock();
}
}
@Override
public E takeFirst() throws InterruptedException {
final ReentrantLock lock = this.lock;
lock.lock();
try {
E x;
while ((x = unlinkFirst()) == null) {
notEmpty.await();
}
return x;
} finally {
lock.unlock();
}
}
@Override
public E takeLast() throws InterruptedException {
final ReentrantLock lock = this.lock;
lock.lock();
try {
E x;
while ((x = unlinkLast()) == null) {
notEmpty.await();
}
return x;
} finally {
lock.unlock();
}
}
@Override
public E pollFirst(long timeout, TimeUnit unit)
throws InterruptedException {
long nanos = unit.toNanos(timeout);
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
E x;
while ((x = unlinkFirst()) == null) {
if (nanos <= 0) {
return null;
}
nanos = notEmpty.awaitNanos(nanos);
}
return x;
} finally {
lock.unlock();
}
}
@Override
public E pollLast(long timeout, TimeUnit unit)
throws InterruptedException {
long nanos = unit.toNanos(timeout);
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
E x;
while ((x = unlinkLast()) == null) {
if (nanos <= 0) {
return null;
}
nanos = notEmpty.awaitNanos(nanos);
}
return x;
} finally {
lock.unlock();
}
}
/**
* @throws NoSuchElementException {@inheritDoc}
*/
@Override
public E getFirst() {
E x = peekFirst();
if (x == null) {
throw new NoSuchElementException();
}
return x;
}
/**
* @throws NoSuchElementException {@inheritDoc}
*/
@Override
public E getLast() {
E x = peekLast();
if (x == null) {
throw new NoSuchElementException();
}
return x;
}
@Override
public E peekFirst() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return (first == null) ? null : first.item;
} finally {
lock.unlock();
}
}
@Override
public E peekLast() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return (last == null) ? null : last.item;
} finally {
lock.unlock();
}
}
@Override
public boolean removeFirstOccurrence(Object o) {
if (o == null) {
return false;
}
final ReentrantLock lock = this.lock;
lock.lock();
try {
for (Node p = first; p != null; p = p.next) {
if (o.equals(p.item)) {
unlink(p);
return true;
}
}
return false;
} finally {
lock.unlock();
}
}
@Override
public boolean removeLastOccurrence(Object o) {
if (o == null) {
return false;
}
final ReentrantLock lock = this.lock;
lock.lock();
try {
for (Node p = last; p != null; p = p.prev) {
if (o.equals(p.item)) {
unlink(p);
return true;
}
}
return false;
} finally {
lock.unlock();
}
}
// BlockingQueue methods
/**
* Inserts the specified element at the end of this deque unless it would
* violate capacity restrictions. When using a capacity-restricted deque,
* it is generally preferable to use method {@link #offer(Object) offer}.
*
* This method is equivalent to {@link #addLast}.
*
* @throws IllegalStateException if this deque is full
* @throws NullPointerException if the specified element is null
*/
@Override
public boolean add(E e) {
addLast(e);
return true;
}
/**
* @throws NullPointerException if the specified element is null
*/
@Override
public boolean offer(E e) {
return offerLast(e);
}
/**
* @throws NullPointerException {@inheritDoc}
* @throws InterruptedException {@inheritDoc}
*/
@Override
public void put(E e) throws InterruptedException {
putLast(e);
}
/**
* @throws NullPointerException {@inheritDoc}
* @throws InterruptedException {@inheritDoc}
*/
@Override
public boolean offer(E e, long timeout, TimeUnit unit)
throws InterruptedException {
return offerLast(e, timeout, unit);
}
/**
* Retrieves and removes the head of the queue represented by this deque.
* This method differs from {@link #poll poll} only in that it throws an
* exception if this deque is empty.
*
* This method is equivalent to {@link #removeFirst() removeFirst}.
*
* @return the head of the queue represented by this deque
* @throws NoSuchElementException if this deque is empty
*/
@Override
public E remove() {
return removeFirst();
}
@Override
public E poll() {
return pollFirst();
}
@Override
public E take() throws InterruptedException {
return takeFirst();
}
@Override
public E poll(long timeout, TimeUnit unit) throws InterruptedException {
return pollFirst(timeout, unit);
}
/**
* Retrieves, but does not remove, the head of the queue represented by
* this deque. This method differs from {@link #peek peek} only in that
* it throws an exception if this deque is empty.
*
* This method is equivalent to {@link #getFirst() getFirst}.
*
* @return the head of the queue represented by this deque
* @throws NoSuchElementException if this deque is empty
*/
@Override
public E element() {
return getFirst();
}
@Override
public E peek() {
return peekFirst();
}
/**
* Returns the number of additional elements that this deque can ideally
* (in the absence of memory or resource constraints) accept without
* blocking. This is always equal to the initial capacity of this deque
* less the current {@code size} of this deque.
*
* Note that you cannot always tell if an attempt to insert
* an element will succeed by inspecting {@code remainingCapacity}
* because it may be the case that another thread is about to
* insert or remove an element.
*/
@Override
public int remainingCapacity() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return capacity - count;
} finally {
lock.unlock();
}
}
/**
* @throws UnsupportedOperationException {@inheritDoc}
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
* @throws IllegalArgumentException {@inheritDoc}
*/
@Override
public int drainTo(Collectionsuper E> c) {
return drainTo(c, Integer.MAX_VALUE);
}
/**
* @throws UnsupportedOperationException {@inheritDoc}
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
* @throws IllegalArgumentException {@inheritDoc}
*/
@Override
public int drainTo(Collectionsuper E> c, int maxElements) {
if (c == null) {
throw new NullPointerException();
}
if (c == this) {
throw new IllegalArgumentException();
}
if (maxElements <= 0) {
return 0;
}
final ReentrantLock lock = this.lock;
lock.lock();
try {
int n = Math.min(maxElements, count);
for (int i = 0; i < n; i++) {
c.add(first.item); // In this order, in case add() throws.
unlinkFirst();
}
return n;
} finally {
lock.unlock();
}
}
// Stack methods
/**
* @throws IllegalStateException if this deque is full
* @throws NullPointerException {@inheritDoc}
*/
@Override
public void push(E e) {
addFirst(e);
}
/**
* @throws NoSuchElementException {@inheritDoc}
*/
@Override
public E pop() {
return removeFirst();
}
// Collection methods
/**
* Removes the first occurrence of the specified element from this deque.
* If the deque does not contain the element, it is unchanged.
* More formally, removes the first element {@code e} such that
* {@code o.equals(e)} (if such an element exists).
* Returns {@code true} if this deque contained the specified element
* (or equivalently, if this deque changed as a result of the call).
*
* This method is equivalent to
* {@link #removeFirstOccurrence(Object) removeFirstOccurrence}.
*
* @param o element to be removed from this deque, if present
* @return {@code true} if this deque changed as a result of the call
*/
@Override
public boolean remove(Object o) {
return removeFirstOccurrence(o);
}
/**
* Returns the number of elements in this deque.
*
* @return the number of elements in this deque
*/
@Override
public int size() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return count;
} finally {
lock.unlock();
}
}
/**
* Returns {@code true} if this deque contains the specified element.
* More formally, returns {@code true} if and only if this deque contains
* at least one element {@code e} such that {@code o.equals(e)}.
*
* @param o object to be checked for containment in this deque
* @return {@code true} if this deque contains the specified element
*/
@Override
public boolean contains(Object o) {
if (o == null) {
return false;
}
final ReentrantLock lock = this.lock;
lock.lock();
try {
for (Node p = first; p != null; p = p.next) {
if (o.equals(p.item)) {
return true;
}
}
return false;
} finally {
lock.unlock();
}
}
/*
* TODO: Add support for more efficient bulk operations.
*
* We don't want to acquire the lock for every iteration, but we
* also want other threads a chance to interact with the
* collection, especially when count is close to capacity.
*/
// /**
// * Adds all of the elements in the specified collection to this
// * queue. Attempts to addAll of a queue to itself result in
// * {@code IllegalArgumentException}. Further, the behavior of
// * this operation is undefined if the specified collection is
// * modified while the operation is in progress.
// *
// * @param c collection containing elements to be added to this queue
// * @return {@code true} if this queue changed as a result of the call
// * @throws ClassCastException {@inheritDoc}
// * @throws NullPointerException {@inheritDoc}
// * @throws IllegalArgumentException {@inheritDoc}
// * @throws IllegalStateException if this deque is full
// * @see #add(Object)
// */
// public boolean addAll(Collection c) {
// if (c == null)
// throw new NullPointerException();
// if (c == this)
// throw new IllegalArgumentException();
// final ReentrantLock lock = this.lock;
// lock.lock();
// try {
// boolean modified = false;
// for (E e : c)
// if (linkLast(e))
// modified = true;
// return modified;
// } finally {
// lock.unlock();
// }
// }
/**
* Returns an array containing all of the elements in this deque, in
* proper sequence (from first to last element).
*
* The returned array will be "safe" in that no references to it are
* maintained by this deque. (In other words, this method must allocate
* a new array). The caller is thus free to modify the returned array.
*
*
This method acts as bridge between array-based and collection-based
* APIs.
*
* @return an array containing all of the elements in this deque
*/
@Override
@SuppressWarnings("unchecked")
public Object[] toArray() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
Object[] a = new Object[count];
int k = 0;
for (Node p = first; p != null; p = p.next) {
a[k++] = p.item;
}
return a;
} finally {
lock.unlock();
}
}
/**
* Returns an array containing all of the elements in this deque, in
* proper sequence; the runtime type of the returned array is that of
* the specified array. If the deque fits in the specified array, it
* is returned therein. Otherwise, a new array is allocated with the
* runtime type of the specified array and the size of this deque.
*
* If this deque fits in the specified array with room to spare
* (i.e., the array has more elements than this deque), the element in
* the array immediately following the end of the deque is set to
* {@code null}.
*
*
Like the {@link #toArray()} method, this method acts as bridge between
* array-based and collection-based APIs. Further, this method allows
* precise control over the runtime type of the output array, and may,
* under certain circumstances, be used to save allocation costs.
*
*
Suppose {@code x} is a deque known to contain only strings.
* The following code can be used to dump the deque into a newly
* allocated array of {@code String}:
*
*
{@code String[] y = x.toArray(new String[0]);}
*
* Note that {@code toArray(new Object[0])} is identical in function to
* {@code toArray()}.
*
* @param a the array into which the elements of the deque are to
* be stored, if it is big enough; otherwise, a new array of the
* same runtime type is allocated for this purpose
* @return an array containing all of the elements in this deque
* @throws ArrayStoreException if the runtime type of the specified array
* is not a supertype of the runtime type of every element in
* this deque
* @throws NullPointerException if the specified array is null
*/
@Override
@SuppressWarnings("unchecked")
public T[] toArray(T[] a) {
final ReentrantLock lock = this.lock;
lock.lock();
try {
if (a.length < count) {
a = (T[]) java.lang.reflect.Array.newInstance
(a.getClass().getComponentType(), count);
}
int k = 0;
for (Node p = first; p != null; p = p.next) {
a[k++] = (T) p.item;
}
if (a.length > k) {
a[k] = null;
}
return a;
} finally {
lock.unlock();
}
}
@Override
public String toString() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
Node p = first;
if (p == null) {
return "[]";
}
StringBuilder sb = new StringBuilder();
sb.append('[');
for (; ; ) {
E e = p.item;
sb.append(e == this ? "(this Collection)" : e);
p = p.next;
if (p == null) {
return sb.append(']').toString();
}
sb.append(',').append(' ');
}
} finally {
lock.unlock();
}
}
/**
* Atomically removes all of the elements from this deque.
* The deque will be empty after this call returns.
*/
@Override
public void clear() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
for (Node f = first; f != null; ) {
f.item = null;
Node n = f.next;
f.prev = null;
f.next = null;
f = n;
}
first = last = null;
count = 0;
notFull.signalAll();
} finally {
lock.unlock();
}
}
/**
* Returns an iterator over the elements in this deque in proper sequence.
* The elements will be returned in order from first (head) to last (tail).
*
* The returned iterator is
* weakly consistent.
*
* @return an iterator over the elements in this deque in proper sequence
*/
@Override
public Iterator iterator() {
return new Itr();
}
/**
* Returns an iterator over the elements in this deque in reverse
* sequential order. The elements will be returned in order from
* last (tail) to first (head).
*
* The returned iterator is
* weakly consistent.
*
* @return an iterator over the elements in this deque in reverse order
*/
@Override
public Iterator descendingIterator() {
return new DescendingItr();
}
/**
* Base class for Iterators for ResizableCapacityLinkedBlockIngQueue
*/
private abstract class AbstractItr implements Iterator<E> {
/**
* The next node to return in next()
*/
Node next;
/**
* nextItem holds on to item fields because once we claim that
* an element exists in hasNext(), we must return item read
* under lock (in advance()) even if it was in the process of
* being removed when hasNext() was called.
*/
E nextItem;
/**
* Node returned by most recent call to next. Needed by remove.
* Reset to null if this element is deleted by a call to remove.
*/
private Node lastRet;
abstract Node firstNode() ;
abstract Node nextNode(Node n) ;
AbstractItr() {
// set to initial position
final ReentrantLock lock = ResizableCapacityLinkedBlockingQueue.this.lock;
lock.lock();
try {
next = firstNode();
nextItem = (next == null) ? null : next.item;
} finally {
lock.unlock();
}
}
/**
* Returns the successor node of the given non-null, but
* possibly previously deleted, node.
*/
private Node succ(Node n) {
// Chains of deleted nodes ending in null or self-links
// are possible if multiple interior nodes are removed.
for (; ; ) {
Node s = nextNode(n);
if (s == null) {
return null;
} else if (s.item != null) {
return s;
} else if (s == n) {
return firstNode();
} else {
n = s;
}
}
}
/**
* Advances next.
*/
void advance() {
final ReentrantLock lock = ResizableCapacityLinkedBlockingQueue.this.lock;
lock.lock();
try {
// assert next != null;
next = succ(next);
nextItem = (next == null) ? null : next.item;
} finally {
lock.unlock();
}
}
@Override
public boolean hasNext() {
return next != null;
}
@Override
public E next() {
if (next == null) {
throw new NoSuchElementException();
}
lastRet = next;
E x = nextItem;
advance();
return x;
}
@Override
public void remove() {
Node n = lastRet;
if (n == null) {
throw new IllegalStateException();
}
lastRet = null;
final ReentrantLock lock = ResizableCapacityLinkedBlockingQueue.this.lock;
lock.lock();
try {
if (n.item != null) {
unlink(n);
}
} finally {
lock.unlock();
}
}
}
/**
* Forward iterator
*/
private class Itr extends AbstractItr {
@Override
Node firstNode() {
return first;
}
@Override
Node nextNode(Node n) {
return n.next;
}
}
/**
* Descending iterator
*/
private class DescendingItr extends AbstractItr {
@Override
Node firstNode() {
return last;
}
@Override
Node nextNode(Node n) {
return n.prev;
}
}
/**
* A customized variant of Spliterators.IteratorSpliterator
*/
static final class LBDSpliterator<E> implements Spliterator<E> {
static final int MAX_BATCH = 1 << 25; // max batch array size;
final ResizableCapacityLinkedBlockingQueue queue;
Node current; // current node; null until initialized
int batch; // batch size for splits
boolean exhausted; // true when no more nodes
long est; // size estimate
LBDSpliterator(ResizableCapacityLinkedBlockingQueue queue) {
this.queue = queue;
this.est = queue.size();
}
@Override
public long estimateSize() {
return est;
}
@Override
public Spliterator trySplit() {
Node h;
final ResizableCapacityLinkedBlockingQueue q = this.queue;
int b = batch;
int n = (b <= 0) ? 1 : (b >= MAX_BATCH) ? MAX_BATCH : b + 1;
if (!exhausted &&
((h = current) != null || (h = q.first) != null) &&
h.next != null) {
Object[] a = new Object[n];
final ReentrantLock lock = q.lock;
int i = 0;
Node p = current;
lock.lock();
try {
if (p != null || (p = q.first) != null) {
do {
if ((a[i] = p.item) != null) {
++i;
}
} while ((p = p.next) != null && i < n);
}
} finally {
lock.unlock();
}
if ((current = p) == null) {
est = 0L;
exhausted = true;
} else if ((est -= i) < 0L) {
est = 0L;
}
if (i > 0) {
batch = i;
return Spliterators.spliterator
(a, 0, i, Spliterator.ORDERED | Spliterator.NONNULL |
Spliterator.CONCURRENT);
}
}
return null;
}
@Override
public void forEachRemaining(Consumersuper E> action) {
if (action == null) {
throw new NullPointerException();
}
final ResizableCapacityLinkedBlockingQueue q = this.queue;
final ReentrantLock lock = q.lock;
if (!exhausted) {
exhausted = true;
Node p = current;
do {
E e = null;
lock.lock();
try {
if (p == null) {
p = q.first;
}
while (p != null) {
e = p.item;
p = p.next;
if (e != null) {
break;
}
}
} finally {
lock.unlock();
}
if (e != null) {
action.accept(e);
}
} while (p != null);
}
}
@Override
public boolean tryAdvance(Consumersuper E> action) {
if (action == null) {
throw new NullPointerException();
}
final ResizableCapacityLinkedBlockingQueue q = this.queue;
final ReentrantLock lock = q.lock;
if (!exhausted) {
E e = null;
lock.lock();
try {
if (current == null) {
current = q.first;
}
while (current != null) {
e = current.item;
current = current.next;
if (e != null) {
break;
}
}
} finally {
lock.unlock();
}
if (current == null) {
exhausted = true;
}
if (e != null) {
action.accept(e);
return true;
}
}
return false;
}
@Override
public int characteristics() {
return Spliterator.ORDERED | Spliterator.NONNULL |
Spliterator.CONCURRENT;
}
}
/**
* Returns a {@link Spliterator} over the elements in this deque.
*
* The returned spliterator is
* weakly consistent.
*
* The {@code Spliterator} reports {@link Spliterator#CONCURRENT},
* {@link Spliterator#ORDERED}, and {@link Spliterator#NONNULL}.
*
* @return a {@code Spliterator} over the elements in this deque
* @implNote The {@code Spliterator} implements {@code trySplit} to permit limited
* parallelism.
* @since 1.8
*/
@Override
public Spliterator spliterator() {
return new LBDSpliterator(this);
}
/**
* Saves this deque to a stream (that is, serializes it).
*
* @param s the stream
* @throws java.io.IOException if an I/O error occurs
* @serialData The capacity (int), followed by elements (each an
* {@code Object}) in the proper order, followed by a null
*/
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException {
final ReentrantLock lock = this.lock;
lock.lock();
try {
// Write out capacity and any hidden stuff
s.defaultWriteObject();
// Write out all elements in the proper order.
for (Node p = first; p != null; p = p.next) {
s.writeObject(p.item);
}
// Use trailing null as sentinel
s.writeObject(null);
} finally {
lock.unlock();
}
}
/**
* Reconstitutes this deque from a stream (that is, deserializes it).
*
* @param s the stream
* @throws ClassNotFoundException if the class of a serialized object
* could not be found
* @throws java.io.IOException if an I/O error occurs
*/
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
s.defaultReadObject();
count = 0;
first = null;
last = null;
// Read in all elements and place in queue
for (; ; ) {
@SuppressWarnings("unchecked")
E item = (E) s.readObject();
if (item == null) {
break;
}
add(item);
}
}
}
- 自定义线程池，增加每个线程处理的耗时，以及平均耗时、最大耗时、最小耗时，以及输出监控日志信息等等；
/**
* 线程池监控类
*
* @author wangtongzhou
* @since 2022-02-23 07:27
*/
public class ThreadPoolMonitor extends ThreadPoolExecutor {
private static final Logger LOGGER = LoggerFactory.getLogger(ThreadPoolMonitor.class);
/**
* 默认拒绝策略
*/
private static final RejectedExecutionHandler defaultHandler = new AbortPolicy();
/**
* 线程池名称，一般以业务名称命名，方便区分
*/
private String poolName;
/**
* 最短执行时间
*/
private Long minCostTime;
/**
* 最长执行时间
*/
private Long maxCostTime;
/**
* 总的耗时
*/
private AtomicLong totalCostTime = new AtomicLong();
private ThreadLocal startTimeThreadLocal = new ThreadLocal<>();
/**
* 调用父类的构造方法，并初始化HashMap和线程池名称
*
* @param corePoolSize 线程池核心线程数
* @param maximumPoolSize 线程池最大线程数
* @param keepAliveTime 线程的最大空闲时间
* @param unit 空闲时间的单位
* @param workQueue 保存被提交任务的队列
* @param poolName 线程池名称
*/
public ThreadPoolMonitor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
TimeUnit unit, BlockingQueue workQueue, String poolName) {
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
Executors.defaultThreadFactory(), poolName);
}
/**
* 调用父类的构造方法，并初始化HashMap和线程池名称
*
* @param corePoolSize 线程池核心线程数
* @param maximumPoolSize 线程池最大线程数
* @param keepAliveTime 线程的最大空闲时间
* @param unit 空闲时间的单位
* @param workQueue 保存被提交任务的队列
* @param
* @param poolName 线程池名称
*/
public ThreadPoolMonitor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
TimeUnit unit, BlockingQueue workQueue, RejectedExecutionHandler handler, String poolName) {
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
Executors.defaultThreadFactory(), handler, poolName);
}
/**
* 调用父类的构造方法，并初始化HashMap和线程池名称
*
* @param corePoolSize 线程池核心线程数
* @param maximumPoolSize 线程池最大线程数
* @param keepAliveTime 线程的最大空闲时间
* @param unit 空闲时间的单位
* @param workQueue 保存被提交任务的队列
* @param threadFactory 线程工厂
* @param poolName 线程池名称
*/
public ThreadPoolMonitor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
TimeUnit unit, BlockingQueue workQueue,
ThreadFactory threadFactory, String poolName) {
super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, defaultHandler);
this.poolName = poolName;
}
/**
* 调用父类的构造方法，并初始化HashMap和线程池名称
*
* @param corePoolSize 线程池核心线程数
* @param maximumPoolSize 线程池最大线程数
* @param keepAliveTime 线程的最大空闲时间
* @param unit 空闲时间的单位
* @param workQueue 保存被提交任务的队列
* @param threadFactory 线程工厂
* @param handler 拒绝策略
* @param poolName 线程池名称
*/
public ThreadPoolMonitor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
TimeUnit unit, BlockingQueue workQueue,
ThreadFactory threadFactory, RejectedExecutionHandler handler, String poolName) {
super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);
this.poolName = poolName;
}
/**
* 线程池延迟关闭时（等待线程池里的任务都执行完毕），统计线程池情况
*/
@Override
public void shutdown() {
// 统计已执行任务、正在执行任务、未执行任务数量
LOGGER.info("{} 关闭线程池， 已执行任务: {}, 正在执行任务: {}, 未执行任务数量: {}",
this.poolName, this.getCompletedTaskCount(), this.getActiveCount(), this.getQueue().size());
super.shutdown();
}
/**
* 线程池立即关闭时，统计线程池情况
*/
@Override
public List shutdownNow() {
// 统计已执行任务、正在执行任务、未执行任务数量
LOGGER.info("{} 立即关闭线程池，已执行任务: {}, 正在执行任务: {}, 未执行任务数量: {}",
this.poolName, this.getCompletedTaskCount(), this.getActiveCount(), this.getQueue().size());
return super.shutdownNow();
}
/**
* 任务执行之前，记录任务开始时间
*/
@Override
protected void beforeExecute(Thread t, Runnable r) {
startTimeThreadLocal.set(System.currentTimeMillis());
}
/**
* 任务执行之后，计算任务结束时间
*/
@Override
protected void afterExecute(Runnable r, Throwable t) {
long costTime = System.currentTimeMillis() - startTimeThreadLocal.get();
startTimeThreadLocal.remove();
maxCostTime = maxCostTime > costTime ? maxCostTime : costTime;
if (getCompletedTaskCount() == 0) {
minCostTime = costTime;
}
minCostTime = minCostTime < costTime ? minCostTime : costTime;
totalCostTime.addAndGet(costTime);
LOGGER.info("{}-pool-monitor: " +
"任务耗时: {} ms, 初始线程数: {}, 核心线程数: {}, 执行的任务数量: {}, " +
"已完成任务数量: {}, 任务总数: {}, 队列里缓存的任务数量: {}, 池中存在的最大线程数: {}, " +
"最大允许的线程数: {}, 线程空闲时间: {}, 线程池是否关闭: {}, 线程池是否终止: {}",
this.poolName,
costTime, this.getPoolSize(), this.getCorePoolSize(), this.getActiveCount(),
this.getCompletedTaskCount(), this.getTaskCount(), this.getQueue().size(), this.getLargestPoolSize(),
this.getMaximumPoolSize(), this.getKeepAliveTime(TimeUnit.MILLISECONDS), this.isShutdown(), this.isTerminated());
}
public Long getMinCostTime() {
return minCostTime;
}
public Long getMaxCostTime() {
return maxCostTime;
}
public long getAverageCostTime(){
if(getCompletedTaskCount()==0||totalCostTime.get()==0){
return 0;
}
return totalCostTime.get()/getCompletedTaskCount();
}
/**
* 生成线程池所用的线程，改写了线程池默认的线程工厂，传入线程池名称，便于问题追踪
*/
static class MonitorThreadFactory implements ThreadFactory {
private static final AtomicInteger poolNumber = new AtomicInteger(1);
private final ThreadGroup group;
private final AtomicInteger threadNumber = new AtomicInteger(1);
private final String namePrefix;
/**
* 初始化线程工厂
*
* @param poolName 线程池名称
*/
MonitorThreadFactory(String poolName) {
SecurityManager s = System.getSecurityManager();
group = Objects.nonNull(s) ? s.getThreadGroup() : Thread.currentThread().getThreadGroup();
namePrefix = poolName + "-pool-" + poolNumber.getAndIncrement() + "-thread-";
}
@Override
public Thread newThread(Runnable r) {
Thread t = new Thread(group, r, namePrefix + threadNumber.getAndIncrement(), 0);
if (t.isDaemon()) {
t.setDaemon(false);
}
if (t.getPriority() != Thread.NORM_PRIORITY) {
t.setPriority(Thread.NORM_PRIORITY);
}
return t;
}
}
}
- 动态修改线程池的类，通过Spring的监听器监控配置刷新方法，实现动态更新线程池的参数；
/**
* 动态刷新线程池
*
* @author wangtongzhou
* @since 2022-03-13 14:13
*/
@Component
@Slf4j
public class DynamicThreadPoolManager {
@Autowired
private DynamicThreadPoolProperties dynamicThreadPoolProperties;
/**
* 存储线程池对象
*/
public Map threadPoolExecutorMap = new HashMap<>();
public Map getThreadPoolExecutorMap() {
return threadPoolExecutorMap;
}
/**
* 初始化线程池
*/
@PostConstruct
public void init() {
createThreadPools(dynamicThreadPoolProperties);
}
/**
* 初始化线程池的创建
*
* @param dynamicThreadPoolProperties
*/
private void createThreadPools(DynamicThreadPoolProperties dynamicThreadPoolProperties) {
dynamicThreadPoolProperties.getExecutors().forEach(config -> {
if (!threadPoolExecutorMap.containsKey(config.getThreadPoolName())) {
ThreadPoolMonitor threadPoolMonitor = new ThreadPoolMonitor(
config.getCorePoolSize(),
config.getMaxPoolSize(),
config.getKeepAliveTime(),
config.getUnit(),
new ResizableCapacityLinkedBlockingQueue<>(config.getQueueCapacity()),
RejectedExecutionHandlerEnum.getRejectedExecutionHandler(config.getRejectedExecutionType()),
config.getThreadPoolName()
);
threadPoolExecutorMap.put(config.getThreadPoolName(),
threadPoolMonitor);
}
});
}
/**
* 调整线程池
*
* @param dynamicThreadPoolProperties
*/
private void changeThreadPools(DynamicThreadPoolProperties dynamicThreadPoolProperties) {
dynamicThreadPoolProperties.getExecutors().forEach(config -> {
ThreadPoolExecutor threadPoolExecutor = threadPoolExecutorMap.get(config.getThreadPoolName());
if (Objects.nonNull(threadPoolExecutor)) {
threadPoolExecutor.setCorePoolSize(config.getCorePoolSize());
threadPoolExecutor.setMaximumPoolSize(config.getMaxPoolSize());
threadPoolExecutor.setKeepAliveTime(config.getKeepAliveTime(), config.getUnit());
threadPoolExecutor.setRejectedExecutionHandler(RejectedExecutionHandlerEnum.getRejectedExecutionHandler(config.getRejectedExecutionType()));
BlockingQueue queue = threadPoolExecutor.getQueue();
if (queue instanceof ResizableCapacityLinkedBlockingQueue) {
((ResizableCapacityLinkedBlockingQueue) queue).setCapacity(config.getQueueCapacity());
}
}
});
}
@EventListener
public void envListener(EnvironmentChangeEvent event) {
log.info("配置发生变更" + event);
changeThreadPools(dynamicThreadPoolProperties);
}
}
- DynamicThreadPoolPropertiesController对外暴露两个方法，第一个通过ContextRefresher提供对外刷新配置的接口，实现及时更新配置信息，第二提供一个查询接口的方法，
/**
* 动态修改线程池参数
*
* @author wangtongzhou
* @since 2022-03-13 17:27
*/
@RestController
public class DynamicThreadPoolPropertiesController {
@Autowired
private ContextRefresher contextRefresher;
@Autowired
private DynamicThreadPoolProperties dynamicThreadPoolProperties;
@Autowired
private DynamicThreadPoolManager dynamicThreadPoolManager;
@PostMapping("/threadPool/properties")
public void update() {
ThreadPoolProperties threadPoolProperties =
dynamicThreadPoolProperties.getExecutors().get(0);
threadPoolProperties.setCorePoolSize(20);
threadPoolProperties.setMaxPoolSize(50);
threadPoolProperties.setQueueCapacity(200);
threadPoolProperties.setRejectedExecutionType("CallerRunsPolicy");
contextRefresher.refresh();
}
@GetMapping("/threadPool/properties")
public Map queryThreadPoolProperties() {
Map metricMap = new HashMap<>();
List 整体上的流程到这里就完成了，算是一个Demo版，对于该组件更深入的思考我认为还可以做以下三件事情:
- 应该以starter的形式嵌入到应用，通过判断启动类加载的Appllo、Nacos还是默认实现；
- 对外可以Push、也可以是日志，还可以支持各种库，提供丰富的输出形式，这个样子的话更加通用化；
- 提供统一查询接口、修改接口、增加权限校验、增加预警规则配置；
参考以下内容:
美团文章
结束
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