前言
這篇是推動大家異步編程的思想的線程池的準備篇，要做好監控，讓大家使用無後顧之憂，敬畏生產。
爲什麼需要對線程池進行監控
Java線程池作爲最常使用到的併發工具，相信大家都不陌生，但是你真的確定使用對了嗎？大名鼎鼎的阿里Java代碼規範要求我們不使用 Executors來快速創建線程池，但是拋棄Executors，使用其它方式創建線程池就一定不會出現問題嗎？本質上對於我們來說線程池本身的運行過程是一個黑盒，我們沒辦法瞭解線程池中的運行狀態時，出現問題沒有辦法及時判斷和預警。面對這種黑盒操作必須通過監控方式讓其透明化，這樣對我們來說才能更好的使用好線程池。因此必須對線程池做監控。
如何做線程池的監控
對於如何做監控，本質就是涉及三點，分別是數據採集、數據存儲以及大盤的展示，接下來我們分說下這三點；
數據採集
採集什麼數據，對於我們來說需要採集就是黑盒的數據，什麼又是線程池的黑盒數據，其實也就是整個線程處理的整個流程，在整個流程中，我們可以通過ThreadPoolExecutor中的七個方法獲取數據，通過這七個方法採集到的數據就可以使線程池的執行過程透明化。
getCorePoolSize()：獲取核心線程數； getMaximumPoolSize：獲取最大線程數； getQueue()：獲取線程池中的阻塞隊列，並通過阻塞隊列中的方法獲取隊列長度、元素個數等； getPoolSize()：獲取線程池中的工作線程數（包括核心線程和非核心線程）； getActiveCount()：獲取活躍線程數，也就是正在執行任務的線程； getLargestPoolSize()：獲取線程池曾經到過的最大工作線程數； getTaskCount()：獲取歷史已完成以及正在執行的總的任務數量；
除了我們瞭解的這些流程以外，ThreadPoolExecutor中還提供了三種鉤子函數，
beforeExecute()：Worker線程執行任務之前會調用的方法； afterExecute()：在Worker線程執行任務之後會調用的方法； terminated()：當線程池從運行狀態變更到TERMINATED狀態之前調用的方法;
對於beforeExecute和afterExecute可以理解爲使用Aop監聽線程執行的時間，這樣子我們可以對每個線程運行的時間整體做監控，terminated可以理解爲線程關閉時候的監控，這樣我們就可以整體獲取採集到線程池生命週期的所有數據了。
數據存儲以及大盤的展示
對於存儲我們這個比較適合採用時序性數據庫，此外現在很多成熟的監控產品都可以滿足我們大屏展示的訴求，這裏推薦下美團Cat和Prometheus，這裏不展開進行講解，大家可以根據自己公司的監控產品進行選擇，對於不同的方案採取的存儲形式會有些差異，甚至自己都可以自定義實現一個功能，反正難度不大。
進一步擴展以及思考
在實際的項目開發中我們會遇到以下場景:
不同的業務採用同一個線程池，這樣如果某個服務阻塞，會影響到整體共用線程池的所有服務，會觸發線程池的拒絕策略； 流量突然增加，需要動態調整線程池的參數，這個時候又不能重啓；
針對這兩種場景，我們對線程池再次進行了深入的思考:
如何合理配置線程池參數； 如何動態調整線程池參數； 如何給不同的服務之間做線程池的隔離；
如何合理配置線程池參數
關於這個問題面試的時候也是經常被問到，我只能說這個問題開始就是一個坑，針對與CPU密集型和I/O密集型，線程池的參數是有不同設計的，也不是遵守幾個公式就可以搞定，當然可以參考，我認爲對於線程池合理的參數的配置是經過多次調整得到的，甚至增加和減少業務都會影響一些參數，我不太建議大家每天背書式的CPU密集型就是N+1，非CPU密集型就是2N，因此我們更希望看到線程池動態配置。
如何動態調整線程池參數
關於如何動態調整線程池，還是回到我們場景問題的解決上，對於流量突增核心就是提升線程池的處理速度，那如何提升線程池的處理速度，有兩種方式，一種是加快業務的處理，也就是消費的快，顯然這種在運行的業務中我們想改變還是比較困難，這個可以作爲覆盤的重點；還有一種就是增加消費者，增加消費者的重點就是調整核心線程數以及非核心線程數的數量。
居於這種思考，這個時候我們需要看下ThreadPoolExecutor線程池源碼，首先看下開始定義的變量，通過變量的設計我們就會發現大師就是大師，大師通過AtomicInteger修飾的ctl變量，高3位存儲了線程池的狀態，低29存儲線程的個數，通過一個變量完成兩件事情，完成狀態判斷以及限制線程最大個數。使用一個HashSet存儲Worker的引用，而Worker繼承了AbstractQueuedSynchronizer，實現一個一個不可衝入的獨佔鎖保證線程的安全性。
//用來標記線程池狀態（高3位），線程個數（低29位）
private final AtomicInteger ctl = new AtomicInteger(ctlOf(RUNNING, 0));
//工作狀態存儲在高3位中
private static final int COUNT_BITS = Integer.SIZE - 3;
//線程個數所能表達的最大數值
private static final int CAPACITY = (1 << COUNT_BITS) - 1;
//線程池狀態
//RUNNING -1 能夠接收新任務，也可以處理阻塞隊列中的任務
private static final int RUNNING = -1 << COUNT_BITS;
//SHUTDOWN 0 不可以接受新任務，繼續處理阻塞隊列中的任務
private static final int SHUTDOWN = 0 << COUNT_BITS;
//STOP 1 不接收新任務，不處理阻塞隊列中的任務，並且會中斷正在處理的任務
private static final int STOP = 1 << COUNT_BITS;
//TIDYING 2 所有任務已經中止，且工作線程數量爲0，最後變遷到這個狀態的線程將要執行terminated()鉤子方法，只會有一個線程執行這個方法；
private static final int TIDYING = 2 << COUNT_BITS;
//TERMINATED 3 中止狀態，已經執行完terminated()鉤子方法
private static final int TERMINATED = 3 << COUNT_BITS;
//任務隊列，當線程池中的線程達到核心線程數量時，再提交任務 就會直接提交到 workQueue
private final BlockingQueue<Runnable> workQueue;
//線程池全局鎖，增加worker減少worker時需要持有mainLock，修改線程池運行狀態時，也需要
private final ReentrantLock mainLock = new ReentrantLock();
//線程池中真正存放worker的地方。
private final HashSet<Worker> workers = new HashSet<Worker>();
private final Condition termination = mainLock.newCondition();
//記錄線程池生命週期內 線程數最大值
private int largestPoolSize;
//記錄線程池所完成任務總數
private long completedTaskCount;
//創建線程會使用線程工廠
private volatile ThreadFactory threadFactory;
//拒絕策略
private volatile RejectedExecutionHandler handler;
//存活時間
private volatile long keepAliveTime;
//控制核心線程數量內的線程 是否可以被回收。true 可以，false不可以。
private volatile boolean allowCoreThreadTimeOut;
//核心線程池數量
private volatile int corePoolSize;
//線程池最大數量
private volatile int maximumPoolSize;
我們的重點看的是volatile修飾的corePoolSize、maximumPoolSize以及keepAliveTime，當然threadFactory和handler也可以看下，不過這兩個不是我們解決動態調整線程池的關鍵。對於這些volatile修飾的關鍵的變量，從併發角度思考的，必然是有併發讀寫的操作才使用volatile修飾的，在指標採集中我們看到其get的方法，對於寫的操作我們可以猜測肯定提供了set的方式，這個時候我們可以搜索下setCorePoolSize，果不其然我們真的搜索到了。
public void setCorePoolSize(int corePoolSize) {
if (corePoolSize < 0)
throw new IllegalArgumentException();
int delta = corePoolSize - this.corePoolSize;
this.corePoolSize = corePoolSize;
//新設置的corePoolSize小於當前核心線程數的時候
//會調用interruptIdleWorkers方法來中斷空閒的工作線程
if (workerCountOf(ctl.get()) > corePoolSize)
interruptIdleWorkers();
else if (delta > 0) {
//當設置的值大於當前值的時候核心線程數的時候
//按照等待隊列中的任務數量來創建新的工作線程
int k = Math.min(delta, workQueue.size());
while (k-- > 0 && addWorker(null, true)) {
if (workQueue.isEmpty())
break;
}
}
}
接下來我們看下interruptIdleWorkers的源碼，此處源碼使用ReentrantLock可重入鎖，因爲Worker的是通過一個全局的HashSer存儲，這裏通過ReentrantLock保證線程安全。
private void interruptIdleWorkers(boolean onlyOne) {
//可重入鎖
final ReentrantLock mainLock = this.mainLock;
mainLock.lock();
try {
for (Worker w : workers) {
Thread t = w.thread;
if (!t.isInterrupted() && w.tryLock()) {
try {
//中斷當前線程
t.interrupt();
} catch (SecurityException ignore) {
} finally {
w.unlock();
}
}
if (onlyOne)
break;
}
} finally {
mainLock.unlock();
}
}
接下來我們在驗證一下是否存在其他相關的參數設置，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;
}
這裏我們會發現一個問題BlockingQueue的隊列容量不能修改，看到美團的文章提供的一個可修改的隊列ResizableCapacityLinkedBlockingQueue，於是乎去看了一下LinkedBlockingQueue的源碼，發現了關於capacity是一個final修飾的，這個時候我就思考一番，這個地方採用volatile修飾，對外暴露可修改，這樣就實現了動態修改阻塞隊列的大小。
如何給不同的服務之間做線程池的隔離
關於如何給不同服務之間做線程池的隔離，這裏我們可以採用Hystrix的艙壁模式，也就是說針對不同服務類型的服務單獨創建線程池，這樣就可以實現服務之間不相互影響，不會因爲某個服務導致整體的服務影響都阻塞。
實現方案
聊了這麼多前置的知識儲備，接下來我們來聊聊實現方案，整體的實現方案我們建立在Spring Boot的基礎實現，採用Spring Cloud刷新動態配置，採用該方式比較合適單體應用，對於有Appllo和Nacos可以通過監聽配置方式的來動態刷新。
Maven依賴如下；
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-context</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.12</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.5</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-core</artifactId>
<version>1.2.3</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.2.3</version>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Hoxton.SR7</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
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
/**
* 線程池配置
*
* @author wangtongzhou
* @since 2022-03-11 21:41
*/
@Data
public class ThreadPoolProperties {
/**
* 線程池名稱
*/
private String threadPoolName;
/**
* 核心線程數
*/
private Integer corePoolSize = Runtime.getRuntime().availableProcessors();
/**
* 最大線程數
*/
private Integer maxPoolSize;
/**
* 隊列最大數量
*/
private Integer queueCapacity;
/**
* 拒絕策略
*/
private String rejectedExecutionType = "AbortPolicy";
/**
* 空閒線程存活時間
*/
private Long keepAliveTime = 1L;
/**
* 空閒線程存活時間單位
*/
private TimeUnit unit = TimeUnit.MILLISECONDS;
}
/**
* 動態刷新線程池配置
*
* @author wangtongzhou
* @since 2022-03-13 14:09
*/
@ConfigurationProperties(prefix = "monitor.threadpool")
@Data
@Component
public class DynamicThreadPoolProperties {
private List<ThreadPoolProperties> executors;
}
自定可修改阻塞隊列大小的方式如下:
/**
* 可重新設定隊列大小的阻塞隊列
*
* @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<E> prev;
/**
* One of:
* - the real successor Node
* - this Node, meaning the successor is head
* - null, meaning there is no successor
*/
Node<E> next;
Node(E x) {
item = x;
}
}
/**
* Pointer to first node.
* Invariant: (first == null && last == null) ||
* (first.prev == null && first.item != null)
*/
transient Node<E> first;
/**
* Pointer to last node.
* Invariant: (first == null && last == null) ||
* (last.next == null && last.item != null)
*/
transient Node<E> 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<? extends E> 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>(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<E> node) {
// assert lock.isHeldByCurrentThread();
if (count >= capacity) {
return false;
}
Node<E> 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<E> node) {
// assert lock.isHeldByCurrentThread();
if (count >= capacity) {
return false;
}
Node<E> 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<E> f = first;
if (f == null) {
return null;
}
Node<E> 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<E> l = last;
if (l == null) {
return null;
}
Node<E> 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<E> x) {
// assert lock.isHeldByCurrentThread();
Node<E> p = x.prev;
Node<E> 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<E> node = new Node<E>(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<E> node = new Node<E>(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<E> node = new Node<E>(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<E> node = new Node<E>(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<E> node = new Node<E>(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<E> node = new Node<E>(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<E> 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<E> 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}.
*
* <p>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.
*
* <p>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.
*
* <p>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.
*
* <p>Note that you <em>cannot</em> 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(Collection<? super E> c) {
return drainTo(c, Integer.MAX_VALUE);
}
/**
* @throws UnsupportedOperationException {@inheritDoc}
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
* @throws IllegalArgumentException {@inheritDoc}
*/
@Override
public int drainTo(Collection<? super 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).
*
* <p>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<E> 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<? extends E> 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).
*
* <p>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.
*
* <p>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<E> 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.
*
* <p>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}.
*
* <p>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.
*
* <p>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}:
*
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
* <p>
* 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> 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<E> 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<E> 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<E> f = first; f != null; ) {
f.item = null;
Node<E> 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).
*
* <p>The returned iterator is
* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
*
* @return an iterator over the elements in this deque in proper sequence
*/
@Override
public Iterator<E> 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).
*
* <p>The returned iterator is
* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
*
* @return an iterator over the elements in this deque in reverse order
*/
@Override
public Iterator<E> 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<E> 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<E> lastRet;
abstract Node<E> firstNode();
abstract Node<E> nextNode(Node<E> 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<E> succ(Node<E> n) {
// Chains of deleted nodes ending in null or self-links
// are possible if multiple interior nodes are removed.
for (; ; ) {
Node<E> 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<E> 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<E> firstNode() {
return first;
}
@Override
Node<E> nextNode(Node<E> n) {
return n.next;
}
}
/**
* Descending iterator
*/
private class DescendingItr extends AbstractItr {
@Override
Node<E> firstNode() {
return last;
}
@Override
Node<E> nextNode(Node<E> 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<E> queue;
Node<E> 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<E> queue) {
this.queue = queue;
this.est = queue.size();
}
@Override
public long estimateSize() {
return est;
}
@Override
public Spliterator<E> trySplit() {
Node<E> h;
final ResizableCapacityLinkedBlockingQueue<E> 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<E> 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(Consumer<? super E> action) {
if (action == null) {
throw new NullPointerException();
}
final ResizableCapacityLinkedBlockingQueue<E> q = this.queue;
final ReentrantLock lock = q.lock;
if (!exhausted) {
exhausted = true;
Node<E> 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(Consumer<? super E> action) {
if (action == null) {
throw new NullPointerException();
}
final ResizableCapacityLinkedBlockingQueue<E> 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.
*
* <p>The returned spliterator is
* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
*
* <p>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<E> spliterator() {
return new LBDSpliterator<E>(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<E> 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);
}
}
}
自定義線程池，增加每個線程處理的耗時，以及平均耗時、最大耗時、最小耗時，以及輸出監控日誌信息等等；
/**
* 線程池監控類
*
* @author wangtongzhou
* @since 2022-02-23 07:27
*/
public class ThreadPoolMonitor extends ThreadPoolExecutor {
private static final Logger LOGGER = LoggerFactory.getLogger(ThreadPoolMonitor.class);
/**
* 默認拒絕策略
*/
private static final RejectedExecutionHandler defaultHandler = new AbortPolicy();
/**
* 線程池名稱，一般以業務名稱命名，方便區分
*/
private String poolName;
/**
* 最短執行時間
*/
private Long minCostTime;
/**
* 最長執行時間
*/
private Long maxCostTime;
/**
* 總的耗時
*/
private AtomicLong totalCostTime = new AtomicLong();
private ThreadLocal<Long> startTimeThreadLocal = new ThreadLocal<>();
/**
* 調用父類的構造方法，並初始化HashMap和線程池名稱
*
* @param corePoolSize 線程池核心線程數
* @param maximumPoolSize 線程池最大線程數
* @param keepAliveTime 線程的最大空閒時間
* @param unit 空閒時間的單位
* @param workQueue 保存被提交任務的隊列
* @param poolName 線程池名稱
*/
public ThreadPoolMonitor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
TimeUnit unit, BlockingQueue<Runnable> workQueue, String poolName) {
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
Executors.defaultThreadFactory(), poolName);
}
/**
* 調用父類的構造方法，並初始化HashMap和線程池名稱
*
* @param corePoolSize 線程池核心線程數
* @param maximumPoolSize 線程池最大線程數
* @param keepAliveTime 線程的最大空閒時間
* @param unit 空閒時間的單位
* @param workQueue 保存被提交任務的隊列
* @param
* @param poolName 線程池名稱
*/
public ThreadPoolMonitor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
TimeUnit unit, BlockingQueue<Runnable> workQueue, RejectedExecutionHandler handler, String poolName) {
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
Executors.defaultThreadFactory(), handler, poolName);
}
/**
* 調用父類的構造方法，並初始化HashMap和線程池名稱
*
* @param corePoolSize 線程池核心線程數
* @param maximumPoolSize 線程池最大線程數
* @param keepAliveTime 線程的最大空閒時間
* @param unit 空閒時間的單位
* @param workQueue 保存被提交任務的隊列
* @param threadFactory 線程工廠
* @param poolName 線程池名稱
*/
public ThreadPoolMonitor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
TimeUnit unit, BlockingQueue<Runnable> workQueue,
ThreadFactory threadFactory, String poolName) {
super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, defaultHandler);
this.poolName = poolName;
}
/**
* 調用父類的構造方法，並初始化HashMap和線程池名稱
*
* @param corePoolSize 線程池核心線程數
* @param maximumPoolSize 線程池最大線程數
* @param keepAliveTime 線程的最大空閒時間
* @param unit 空閒時間的單位
* @param workQueue 保存被提交任務的隊列
* @param threadFactory 線程工廠
* @param handler 拒絕策略
* @param poolName 線程池名稱
*/
public ThreadPoolMonitor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
TimeUnit unit, BlockingQueue<Runnable> workQueue,
ThreadFactory threadFactory, RejectedExecutionHandler handler, String poolName) {
super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);
this.poolName = poolName;
}
/**
* 線程池延遲關閉時（等待線程池裏的任務都執行完畢），統計線程池情況
*/
@Override
public void shutdown() {
// 統計已執行任務、正在執行任務、未執行任務數量
LOGGER.info("{} 關閉線程池， 已執行任務: {}, 正在執行任務: {}, 未執行任務數量: {}",
this.poolName, this.getCompletedTaskCount(), this.getActiveCount(), this.getQueue().size());
super.shutdown();
}
/**
* 線程池立即關閉時，統計線程池情況
*/
@Override
public List<Runnable> shutdownNow() {
// 統計已執行任務、正在執行任務、未執行任務數量
LOGGER.info("{} 立即關閉線程池，已執行任務: {}, 正在執行任務: {}, 未執行任務數量: {}",
this.poolName, this.getCompletedTaskCount(), this.getActiveCount(), this.getQueue().size());
return super.shutdownNow();
}
/**
* 任務執行之前，記錄任務開始時間
*/
@Override
protected void beforeExecute(Thread t, Runnable r) {
startTimeThreadLocal.set(System.currentTimeMillis());
}
/**
* 任務執行之後，計算任務結束時間
*/
@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: " +
"任務耗時: {} ms, 初始線程數: {}, 核心線程數: {}, 執行的任務數量: {}, " +
"已完成任務數量: {}, 任務總數: {}, 隊列裏緩存的任務數量: {}, 池中存在的最大線程數: {}, " +
"最大允許的線程數: {}, 線程空閒時間: {}, 線程池是否關閉: {}, 線程池是否終止: {}",
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();
}
/**
* 生成線程池所用的線程，改寫了線程池默認的線程工廠，傳入線程池名稱，便於問題追蹤
*/
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;
/**
* 初始化線程工廠
*
* @param poolName 線程池名稱
*/
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;
}
}
}
動態修改線程池的類，通過Spring的監聽器監控配置刷新方法，實現動態更新線程池的參數；
/**
* 動態刷新線程池
*
* @author wangtongzhou
* @since 2022-03-13 14:13
*/
@Component
@Slf4j
public class DynamicThreadPoolManager {
@Autowired
private DynamicThreadPoolProperties dynamicThreadPoolProperties;
/**
* 存儲線程池對象
*/
public Map<String, ThreadPoolMonitor> threadPoolExecutorMap = new HashMap<>();
public Map<String, ThreadPoolMonitor> getThreadPoolExecutorMap() {
return threadPoolExecutorMap;
}
/**
* 初始化線程池
*/
@PostConstruct
public void init() {
createThreadPools(dynamicThreadPoolProperties);
}
/**
* 初始化線程池的創建
*
* @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);
}
});
}
/**
* 調整線程池
*
* @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<Runnable> queue = threadPoolExecutor.getQueue();
if (queue instanceof ResizableCapacityLinkedBlockingQueue) {
((ResizableCapacityLinkedBlockingQueue<Runnable>) queue).setCapacity(config.getQueueCapacity());
}
}
});
}
@EventListener
public void envListener(EnvironmentChangeEvent event) {
log.info("配置發生變更" + event);
changeThreadPools(dynamicThreadPoolProperties);
}
}
DynamicThreadPoolPropertiesController對外暴露兩個方法，第一個通過ContextRefresher提供對外刷新配置的接口，實現及時更新配置信息，第二提供一個查詢接口的方法，
/**
* 動態修改線程池參數
*
* @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<String, Object> queryThreadPoolProperties() {
Map<String, Object> metricMap = new HashMap<>();
List<Map> threadPools = new ArrayList<>();
dynamicThreadPoolManager.getThreadPoolExecutorMap().forEach((k, v) -> {
ThreadPoolMonitor threadPoolMonitor = (ThreadPoolMonitor) v;
Map<String, Object> poolInfo = new HashMap<>();
poolInfo.put("thread.pool.name", k);
poolInfo.put("thread.pool.core.size", threadPoolMonitor.getCorePoolSize());
poolInfo.put("thread.pool.largest.size", threadPoolMonitor.getLargestPoolSize());
poolInfo.put("thread.pool.max.size", threadPoolMonitor.getMaximumPoolSize());
poolInfo.put("thread.pool.thread.count", threadPoolMonitor.getPoolSize());
poolInfo.put("thread.pool.max.costTime", threadPoolMonitor.getMaxCostTime());
poolInfo.put("thread.pool.average.costTime", threadPoolMonitor.getAverageCostTime());
poolInfo.put("thread.pool.min.costTime", threadPoolMonitor.getMinCostTime());
poolInfo.put("thread.pool.active.count", threadPoolMonitor.getActiveCount());
poolInfo.put("thread.pool.completed.taskCount", threadPoolMonitor.getCompletedTaskCount());
poolInfo.put("thread.pool.queue.name", threadPoolMonitor.getQueue().getClass().getName());
poolInfo.put("thread.pool.rejected.name", threadPoolMonitor.getRejectedExecutionHandler().getClass().getName());
poolInfo.put("thread.pool.task.count", threadPoolMonitor.getTaskCount());
threadPools.add(poolInfo);
});
metricMap.put("threadPools", threadPools);
return metricMap;
}
}
整體上的流程到這裏就完成了，算是一個Demo版，對於該組件更深入的思考我認爲還可以做以下三件事情:
應該以starter的形式嵌入到應用，通過判斷啓動類加載的Appllo、Nacos還是默認實現； 對外可以Push、也可以是日誌，還可以支持各種庫，提供豐富的輸出形式，這個樣子的話更加通用化； 提供統一查詢接口、修改接口、增加權限校驗、增加預警規則配置；
參考以下內容:
結束
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