jar包
Maven: org.springframework.boot:spring-boot-autoconfigure:2.1.7.RELEASE
设置参数
server:
port: 10000
servlet:
context-path: /
tomcat:
max-connections: 10 #默认10000 接受和处理的最大连接数
accept-count: 100 #默认100
#默认10 初始化时创建的线程数 适当增大一些，以便应对突然增长的访问量100
min-spare-threads: 10
max-threads: 200 #默认200 最大并发数
org.apache.tomcat.util.net.NioEndpoint
# accept-count 其实就是backlog
serverSock = ServerSocketChannel.open();
socketProperties.setProperties(serverSock.socket());
InetSocketAddress addr = new InetSocketAddress(getAddress(), getPortWithOffset());
serverSock.socket().bind(addr,getAcceptCount());max-connections
public class LimitLatch {
private static final Log log = LogFactory.getLog(LimitLatch.class);
private class Sync extends AbstractQueuedSynchronizer {
private static final long serialVersionUID = 1L;
public Sync() {
}
@Override
protected int tryAcquireShared(int ignored) {
long newCount = count.incrementAndGet();
if (!released && newCount > limit) {
// Limit exceeded
count.decrementAndGet();
return -1;
} else {
return 1;
}
}
@Override
protected boolean tryReleaseShared(int arg) {
count.decrementAndGet();
return true;
}
}
private final Sync sync;
private final AtomicLong count;
private volatile long limit;
private volatile boolean released = false;
/**
* Instantiates a LimitLatch object with an initial limit.
* @param limit - maximum number of concurrent acquisitions of this latch
*/
public LimitLatch(long limit) {
this.limit = limit;
this.count = new AtomicLong(0);
this.sync = new Sync();
}
/**
* Returns the current count for the latch
* @return the current count for latch
*/
public long getCount() {
return count.get();
}
/**
* Obtain the current limit.
* @return the limit
*/
public long getLimit() {
return limit;
}
/**
* Sets a new limit. If the limit is decreased there may be a period where
* more shares of the latch are acquired than the limit. In this case no
* more shares of the latch will be issued until sufficient shares have been
* returned to reduce the number of acquired shares of the latch to below
* the new limit. If the limit is increased, threads currently in the queue
* may not be issued one of the newly available shares until the next
* request is made for a latch.
*
* @param limit The new limit
*/
public void setLimit(long limit) {
this.limit = limit;
}
/**
* Acquires a shared latch if one is available or waits for one if no shared
* latch is current available.
* @throws InterruptedException If the current thread is interrupted
*/
public void countUpOrAwait() throws InterruptedException {
if (log.isDebugEnabled()) {
log.debug("Counting up["+Thread.currentThread().getName()+"] latch="+getCount());
}
sync.acquireSharedInterruptibly(1);
}
/**
* Releases a shared latch, making it available for another thread to use.
* @return the previous counter value
*/
public long countDown() {
sync.releaseShared(0);
long result = getCount();
if (log.isDebugEnabled()) {
log.debug("Counting down["+Thread.currentThread().getName()+"] latch="+result);
}
return result;
}
/**
* Releases all waiting threads and causes the {@link #limit} to be ignored
* until {@link #reset()} is called.
* @return <code>true</code> if release was done
*/
public boolean releaseAll() {
released = true;
return sync.releaseShared(0);
}
/**
* Resets the latch and initializes the shared acquisition counter to zero.
* @see #releaseAll()
*/
public void reset() {
this.count.set(0);
released = false;
}
/**
* Returns <code>true</code> if there is at least one thread waiting to
* acquire the shared lock, otherwise returns <code>false</code>.
* @return <code>true</code> if threads are waiting
*/
public boolean hasQueuedThreads() {
return sync.hasQueuedThreads();
}
/**
* Provide access to the list of threads waiting to acquire this limited
* shared latch.
* @return a collection of threads
*/
public Collection<Thread> getQueuedThreads() {
return sync.getQueuedThreads();
}
}
org.apache.tomcat.util.net.AbstractEndpoint
private int maxConnections = 10000;
public void setMaxConnections(int maxCon) {
this.maxConnections = maxCon;
LimitLatch latch = this.connectionLimitLatch;
if (latch != null) {
// Update the latch that enforces this
if (maxCon == -1) {
releaseConnectionLatch();
} else {
latch.setLimit(maxCon);
}
} else if (maxCon > 0) {
initializeConnectionLatch();
}
}
min-spare-threads
如果是ThreadPoolExecutor，那就是corePoolSize
private int minSpareThreads = 10;
public void setMinSpareThreads(int minSpareThreads) {
this.minSpareThreads = minSpareThreads;
Executor executor = this.executor;
if (internalExecutor && executor instanceof java.util.concurrent.ThreadPoolExecutor) {
// The internal executor should always be an instance of
// j.u.c.ThreadPoolExecutor but it may be null if the endpoint is
// not running.
// This check also avoids various threading issues.
((java.util.concurrent.ThreadPoolExecutor) executor).setCorePoolSize(minSpareThreads);
}
}
如果是ThreadPoolExecutor，那就是maximumPoolSizeprivate int maxThreads = 200;
public void setMaxThreads(int maxThreads) {
this.maxThreads = maxThreads;
Executor executor = this.executor;
if (internalExecutor && executor instanceof java.util.concurrent.ThreadPoolExecutor) {
// The internal executor should always be an instance of
// j.u.c.ThreadPoolExecutor but it may be null if the endpoint is
// not running.
// This check also avoids various threading issues.
((java.util.concurrent.ThreadPoolExecutor) executor).setMaximumPoolSize(maxThreads);
}
}例子1
server:
port: 10000
servlet:
context-path: /
tomcat:
max-connections: 10 #默认10000
accept-count: 5 #默认100max-connections配置10，accept-count配置5，这样就是tomcat最多可以接收15个connection，
现在jmeter发送20个请求，则有5个连接被拒绝
