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From "Ken DeLong" <ken.del...@babycenter.com>
Subject RE: Too Many Connections
Date Fri, 27 Jun 2008 16:08:47 GMT
That didn't help.  We changed to  

	private HttpClient client = new HttpClient(new
SimpleHttpConnectionManager());

But we still see the same behavior.

Turning on the debug logs shows messages like 

$ fgrep 'Connection is locked.  Call to releaseConnection() ignored.'
server.log | wc -l
176

$ fgrep 'Releasing connection back to connection manager.' server.log |
wc -l
264


What would cause the connection to be locked when releaseConnection() is
called?



-----Original Message-----
From: Pete Keyes [mailto:PKeyes@starbucks.com] 
Sent: Thursday, June 26, 2008 3:27 PM
To: HttpClient User Discussion
Cc: Stephen Hiley
Subject: RE: Too Many Connections

You need to use either of these:
  - org.apache.commons.httpclient.MultiThreadedHttpConnectionManager
  - org.apache.commons.httpclient.SimpleHttpConnectionManager
There are examples of both in the HttpClient site.

In addition to that you may need to tune the O/S to formally release the
CLOSE_WAIT files sooner.  There is a delay between when an application
closes a socket and when the O/S can formally release that socket to
avoid orphan packets.

See the documentation for your O/S on setting that value.

 
...Pete
Starbucks Coffee Co.
2601 Utah Ave S.
Seattle, WA. 98134
(w) 206-318-5933
(c) 206-914-4134

-----Original Message-----
From: Ken DeLong [mailto:ken.delong@babycenter.com]
Sent: Thursday, June 26, 2008 3:17 PM
To: httpclient-users@hc.apache.org
Cc: Stephen Hiley
Subject: Too Many Connections

We have a method in our app that calls httpclient like this:

	private HttpClient client = new HttpClient();
	
	public String send(String urlString, String xml)
	{
		PostMethod postMethod = new PostMethod(urlString);
		
		// Put the XML in the request
		try
		{
			RequestEntity entity = new
StringRequestEntity(xml, "text/xml", "UTF-8");
			postMethod.setRequestEntity(entity);
		}
		catch(UnsupportedEncodingException e1)
		{
			logger.warn("Couldn't encode the xml?", e1);
			return "" +
IContentPublishingService.ACTION_ERROR;
		}

		// Send the data and get the response
		String response = null;
		try
		{
			client.executeMethod(postMethod);
			byte[] responseBody =
postMethod.getResponseBody();
			response = new String(responseBody);
		}
		catch(HttpException e)
		{
			logger.warn("Fatal protocol violation: " +
e.getMessage());
			return "" +
IContentPublishingService.ACTION_ERROR;		
		}
		catch(IOException e)
		{
			logger.warn("Fatal transport error: " +
e.getMessage());
			return "" +
IContentPublishingService.ACTION_ERROR;
		}
		finally
		{
			// Release the connection.
			postMethod.releaseConnection();
		}

		return response;
	}


This method is called rapidly by a single thread in our application.
After 1500 calls or so, we start to see java.net.SocketException, too
many open files.  Netstat reveals that there are many sockets in
CLOSE_WAIT and TIME_WAIT states.  It seems that httpclient is not
reusing the connection managed by the HttpClient instance, and instead
is closing the connection and creating a new one.  This appears to be in
conflict with all the documentation that we could find.

An interesting wrinkle is that the sending and receiving side of the
connection are both on the same machine.  The URL is constructed using
the machine's dns name, not "localhost".

------------------------------------------------------------------------
--
Kenneth DeLong
Software Architect
Engineering
BabyCenter, LLC

kdelong@babycenter.com
p:  415.344.7616
AIM: kenwdelong

http://www.babycenter.com



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