HttpClient连接池抛出大量ConnectionPoolTimeoutException: Timeout waiting for connection异

今天解决了一个HttpClient的异常，汗啊，一个HttpClient使用稍有不慎都会是毁灭级别的啊。

这里有之前因为route配置不当导致服务器异常的一个处理：https://www.geek-share.com/detail/2516191343.html

里面的HttpConnectionManager实现就是我在这里使用的实现。

 

问题表现：

tomcat后台日志发现大量异常

 

[plain] view plaincopyprint?

1. org.apache.http.conn.ConnectionPoolTimeoutException: Timeout waiting for connection

org.apache.http.conn.ConnectionPoolTimeoutException: Timeout waiting for connection

时间一长tomcat就无法继续处理其他请求，从假死变成真死了。

 

linux运行：

[plain] view plaincopyprint?

1. netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'

netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'

发现CLOSE_WAIT的数量始终在400以上，一直没降过。

 

 

问题分析：

一开始我对我的HttpClient使用过程深信不疑，我不认为异常是来自这里。

所以我开始从TCP的连接状态入手，猜测可能导致异常的原因。以前经常遇到TIME_WAIT数过大导致的服务器异常，很容易解决，修改下sysctl就ok了。但是这次是CLOSE_WAIT，是完全不同的概念了。

关于TIME_WAIT和CLOSE_WAIT的区别和异常处理我会单独起一篇文章详细说说我的理解。

 

简单来说CLOSE_WAIT数目过大是由于被动关闭连接处理不当导致的。

我说一个场景，服务器A会去请求服务器B上面的apache获取文件资源，正常情况下，如果请求成功，那么在抓取完资源后服务器A会主动发出关闭连接的请求，这个时候就是主动关闭连接，连接状态我们可以看到是TIME_WAIT。如果一旦发生异常呢？假设请求的资源服务器B上并不存在，那么这个时候就会由服务器B发出关闭连接的请求，服务器A就是被动的关闭了连接，如果服务器A被动关闭连接之后自己并没有释放连接，那就会造成CLOSE_WAIT的状态了。

所以很明显，问题还是处在程序里头。

 

先看看我的HttpConnectionManager实现：

 

[java] view plaincopyprint?

1. publicclass HttpConnectionManager {
2. privatestatic HttpParams httpParams;
3. privatestatic ClientConnectionManager connectionManager;
4. /**
5. * 最大连接数
6. */
7. publicfinalstaticint MAX_TOTAL_CONNECTIONS = 800;
8. /**
9. * 获取连接的最大等待时间
10. */
11. publicfinalstaticint WAIT_TIMEOUT = 60000;
12. /**
13. * 每个路由最大连接数
14. */
15. publicfinalstaticint MAX_ROUTE_CONNECTIONS = 400;
16. /**
17. * 连接超时时间
18. */
19. publicfinalstaticint CONNECT_TIMEOUT = 10000;
20. /**
21. * 读取超时时间
22. */
23. publicfinalstaticint READ_TIMEOUT = 10000;
24. static {
25. httpParams = new BasicHttpParams();
26. // 设置最大连接数
27. ConnManagerParams.setMaxTotalConnections(httpParams, MAX_TOTAL_CONNECTIONS);
28. // 设置获取连接的最大等待时间
29. ConnManagerParams.setTimeout(httpParams, WAIT_TIMEOUT);
30. // 设置每个路由最大连接数
31. ConnPerRouteBean connPerRoute = new ConnPerRouteBean(MAX_ROUTE_CONNECTIONS);
32. ConnManagerParams.setMaxConnectionsPerRoute(httpParams,connPerRoute);
33. // 设置连接超时时间
34. HttpConnectionParams.setConnectionTimeout(httpParams, CONNECT_TIMEOUT);
35. // 设置读取超时时间
36. HttpConnectionParams.setSoTimeout(httpParams, READ_TIMEOUT);
37. SchemeRegistry registry = new SchemeRegistry();
38. registry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
39. registry.register(new Scheme("https", SSLSocketFactory.getSocketFactory(), 443));
40. connectionManager = new ThreadSafeClientConnManager(httpParams, registry);
41. }
42. publicstatic HttpClient getHttpClient() {
43. returnnew DefaultHttpClient(connectionManager, httpParams);
44. }
45. }

public class HttpConnectionManager {

private static HttpParams httpParams;
private static ClientConnectionManager connectionManager;

/**
* 最大连接数
*/
public final static int MAX_TOTAL_CONNECTIONS = 800;
/**
* 获取连接的最大等待时间
*/
public final static int WAIT_TIMEOUT = 60000;
/**
* 每个路由最大连接数
*/
public final static int MAX_ROUTE_CONNECTIONS = 400;
/**
* 连接超时时间
*/
public final static int CONNECT_TIMEOUT = 10000;
/**
* 读取超时时间
*/
public final static int READ_TIMEOUT = 10000;

static {
httpParams = new BasicHttpParams();
// 设置最大连接数
ConnManagerParams.setMaxTotalConnections(httpParams, MAX_TOTAL_CONNECTIONS);
// 设置获取连接的最大等待时间
ConnManagerParams.setTimeout(httpParams, WAIT_TIMEOUT);
// 设置每个路由最大连接数
ConnPerRouteBean connPerRoute = new ConnPerRouteBean(MAX_ROUTE_CONNECTIONS);
ConnManagerParams.setMaxConnectionsPerRoute(httpParams,connPerRoute);
// 设置连接超时时间
HttpConnectionParams.setConnectionTimeout(httpParams, CONNECT_TIMEOUT);
// 设置读取超时时间
HttpConnectionParams.setSoTimeout(httpParams, READ_TIMEOUT);

SchemeRegistry registry = new SchemeRegistry();
registry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
registry.register(new Scheme("https", SSLSocketFactory.getSocketFactory(), 443));

connectionManager = new ThreadSafeClientConnManager(httpParams, registry);
}

public static HttpClient getHttpClient() {
return new DefaultHttpClient(connectionManager, httpParams);
}

}

 

 

看到没MAX_ROUTE_CONNECTIONS 正好是400，跟CLOSE_WAIT非常接近啊，难道是巧合？继续往下看。

然后看看调用它的代码是什么样的：

 

[java] view plaincopyprint?

1. publicstatic String readNet (String urlPath)
2. {
3. StringBuffer sb = new StringBuffer ();
4. HttpClient client = null;
5. InputStream in = null;
6. InputStreamReader isr = null;
7. try
8. {
9. client = HttpConnectionManager.getHttpClient();
10. HttpGet get = new HttpGet();
11. get.setURI(new URI(urlPath));
12. HttpResponse response = client.execute(get);
13. if (response.getStatusLine ().getStatusCode () != 200) {
14. returnnull;
15. }
16. HttpEntity entity =response.getEntity();
17. if( entity != null ){
18. in = entity.getContent();
19. .....
20. }
21. return sb.toString ();
22. }
23. catch (Exception e)
24. {
25. e.printStackTrace ();
26. returnnull;
27. }
28. finally
29. {
30. if (isr != null){
31. try
32. {
33. isr.close ();
34. }
35. catch (IOException e)
36. {
37. e.printStackTrace ();
38. }
39. }
40. if (in != null){
41. try
42. {
43. <span style="color: rgb(255, 0, 0);">in.close ();</span>
44. }
45. catch (IOException e)
46. {
47. e.printStackTrace ();
48. }
49. }
50. }
51. }

public static String readNet (String urlPath)
{
StringBuffer sb = new StringBuffer ();
HttpClient client = null;
InputStream in = null;
InputStreamReader isr = null;
try
{
client = HttpConnectionManager.getHttpClient();
HttpGet get = new HttpGet();
get.setURI(new URI(urlPath));
HttpResponse response = client.execute(get);
if (response.getStatusLine ().getStatusCode () != 200) {
return null;
}
HttpEntity entity =response.getEntity();

if( entity != null ){
in = entity.getContent();
.....
}
return sb.toString ();

}
catch (Exception e)
{
e.printStackTrace ();
return null;
}
finally
{
if (isr != null){
try
{
isr.close ();
}
catch (IOException e)
{
e.printStackTrace ();
}
}
if (in != null){
try
{
in.close ();
}
catch (IOException e)
{
e.printStackTrace ();
}
}
}
}

很简单，就是个远程读取中文页面的方法。值得注意的是这一段代码是后来某某同学加上去的，看上去没啥问题，是用于非200状态的异常处理：

 

 

[java] view plaincopyprint?

1. if (response.getStatusLine ().getStatusCode () != 200) {
2. returnnull;
3. }

if (response.getStatusLine ().getStatusCode () != 200) {
return null;
}

代码本身没有问题，但是问题是放错了位置。如果这么写的话就没问题：

 

 

[java] view plaincopyprint?

1. client = HttpConnectionManager.getHttpClient();
2. HttpGet get = new HttpGet();
3. get.setURI(new URI(urlPath));
4. HttpResponse response = client.execute(get);
5. HttpEntity entity =response.getEntity();
6. if( entity != null ){
7. in = entity.getContent();
8. ..........
9. }
10. if (response.getStatusLine ().getStatusCode () != 200) {
11. returnnull;
12. }
13. return sb.toString ();

client = HttpConnectionManager.getHttpClient();
HttpGet get = new HttpGet();
get.setURI(new URI(urlPath));
HttpResponse response = client.execute(get);

HttpEntity entity =response.getEntity();

if( entity != null ){
in = entity.getContent();
..........
}

if (response.getStatusLine ().getStatusCode () != 200) {
return null;
}
return sb.toString ();

看出毛病了吧。在这篇入门（HttpClient4.X 升级 入门 + http连接池使用）里头我提到了HttpClient4使用我们常用的InputStream.close()来确认连接关闭，前面那种写法InputStream in 根本就不会被赋值，意味着一旦出现非200的连接，这个连接将永远僵死在连接池里头，太恐怖了。。。所以我们看到CLOST_WAIT数目为400，因为对一个路由的连接已经完全被僵死连接占满了。。。

 

其实上面那段代码还有一个没处理好的地方，异常处理不够严谨，所以最后我把代码改成了这样：

 

[java] view plaincopyprint?

1. publicstatic String readNet (String urlPath)
2. {
3. StringBuffer sb = new StringBuffer ();
4. HttpClient client = null;
5. InputStream in = null;
6. InputStreamReader isr = null;
7. HttpGet get = new HttpGet();
8. try
9. {
10. client = HttpConnectionManager.getHttpClient();
11. get.setURI(new URI(urlPath));
12. HttpResponse response = client.execute(get);
13. if (response.getStatusLine ().getStatusCode () != 200) {
14. get.abort();
15. returnnull;
16. }
17. HttpEntity entity =response.getEntity();
18. if( entity != null ){
19. in = entity.getContent();
20. ......
21. }
22. return sb.toString ();
23. }
24. catch (Exception e)
25. {
26. get.abort();
27. e.printStackTrace ();
28. returnnull;
29. }
30. finally
31. {
32. if (isr != null){
33. try
34. {
35. isr.close ();
36. }
37. catch (IOException e)
38. {
39. e.printStackTrace ();
40. }
41. }
42. if (in != null){
43. try
44. {
45. in.close ();
46. }
47. catch (IOException e)
48. {
49. e.printStackTrace ();
50. }
51. }
52. }
53. }

public static String readNet (String urlPath)
{
StringBuffer sb = new StringBuffer ();
HttpClient client = null;
InputStream in = null;
InputStreamReader isr = null;
HttpGet get = new HttpGet();
try
{
client = HttpConnectionManager.getHttpClient();
get.setURI(new URI(urlPath));
HttpResponse response = client.execute(get);
if (response.getStatusLine ().getStatusCode () != 200) {
get.abort();
return null;
}
HttpEntity entity =response.getEntity();

if( entity != null ){
in = entity.getContent();
......
}
return sb.toString ();

}
catch (Exception e)
{
get.abort();
e.printStackTrace ();
return null;
}
finally
{
if (isr != null){
try
{
isr.close ();
}
catch (IOException e)
{
e.printStackTrace ();
}
}
if (in != null){
try
{
in.close ();
}
catch (IOException e)
{
e.printStackTrace ();
}
}
}
}

 

 

显示调用HttpGet的abort，这样就会直接中止这次连接，我们在遇到异常的时候应该显示调用，因为谁能保证异常是在InputStream in赋值之后才抛出的呢。

 

好了 ，分析完毕，明天准备总结下CLOSE_WAIT和TIME_WAIT的区别。

 

 

 

原文：https://www.geek-share.com/detail/2521991075.html

阅读更多