CloseableHttpClient httpClient = HttpClients.custom() .setConnectionManager(connectionManager) .setMaxConnTotal(400) .setMaxConnPerRoute(150) .evictExpiredConnections() .build();
evictExpiredConnections 这个配置作用：
设置一个定时线程，定时清理闲置连接,可以将这个定时时间设置为 keep alive timeout 时间的一半以保证超时前回收
每个httpClient 对象都会有自己独立的定时线程
这样如果应用中httpClient对象很多，就会导致上图中线程太多
源码中，如果设置了evictExpiredConnections 会有下面一段逻辑
List<Closeable> closeablesCopy = closeables != null ? new ArrayList<Closeable>(closeables) : null;
if (!this.connManagerShared) {
if (closeablesCopy == null) {
closeablesCopy = new ArrayList<Closeable>(1);
}
final HttpClientConnectionManager cm = connManagerCopy;
if (evictExpiredConnections || evictIdleConnections) {
final IdleConnectionEvictor connectionEvictor = new IdleConnectionEvictor(cm,
maxIdleTime > 0 ? maxIdleTime : 10, maxIdleTimeUnit != null ? maxIdleTimeUnit : TimeUnit.SECONDS,
maxIdleTime, maxIdleTimeUnit);
closeablesCopy.add(new Closeable() {
@Override
public void close() throws IOException {
connectionEvictor.shutdown();
try {
connectionEvictor.awaitTermination(1L, TimeUnit.SECONDS);
} catch (final InterruptedException interrupted) {
Thread.currentThread().interrupt();
}
}
});
connectionEvictor.start();
}
closeablesCopy.add(new Closeable() {
@Override
public void close() throws IOException {
cm.shutdown();
}
});
}
IdleConnectionEvictor 对象是
public final class IdleConnectionEvictor {
private final HttpClientConnectionManager connectionManager;
private final ThreadFactory threadFactory;
private final Thread thread;
private final long sleepTimeMs;
private final long maxIdleTimeMs;
private volatile Exception exception;
public IdleConnectionEvictor(
final HttpClientConnectionManager connectionManager,
final ThreadFactory threadFactory,
final long sleepTime, final TimeUnit sleepTimeUnit,
final long maxIdleTime, final TimeUnit maxIdleTimeUnit) {
this.connectionManager = Args.notNull(connectionManager, "Connection manager");
this.threadFactory = threadFactory != null ? threadFactory : new DefaultThreadFactory();
this.sleepTimeMs = sleepTimeUnit != null ? sleepTimeUnit.toMillis(sleepTime) : sleepTime;
this.maxIdleTimeMs = maxIdleTimeUnit != null ? maxIdleTimeUnit.toMillis(maxIdleTime) : maxIdleTime;
this.thread = this.threadFactory.newThread(new Runnable() {
@Override
public void run() {
try {
while (!Thread.currentThread().isInterrupted()) {
Thread.sleep(sleepTimeMs);
connectionManager.closeExpiredConnections();
if (maxIdleTimeMs > 0) {
connectionManager.closeIdleConnections(maxIdleTimeMs, TimeUnit.MILLISECONDS);
}
}
} catch (final Exception ex) {
exception = ex;
}
}
});
}
会出现一个线程，这个线程里面就是去关闭超时不用的闲置链接
