On Thu, 2008-08-28 at 14:51 +0300, Dobri Kitipov wrote: > Hi, > > I am trying to explain myself how the "keep-alive", or TCP connection > persistence, is supposed to work? I have read several resources about that, > but I still have some questions ( > http://java.sun.com/j2se/1.5.0/docs/guide/net/http-keepalive.html > > http://hc.apache.org/httpclient-3.x/performance.html > > http://www.io.com/~maus/HttpKeepAlive.html<http://www.io.com/%7Emaus/HttpKeepAlive.html> > ). > > > > How can I verify that "keep-alive" is really used? I know that for http 1.1 > keep-alive is by default, but does it mean that the TCP socket is reused?
Yes, it does. > I > mean how can I debug and verify that a TCP connection is reused. Does it > mean that a socket is reused? > Turning on the context logging would be one option. > > > I have executed several debug sessions using as a sample an Axis2 1.4 > client, that in turns uses commons-httpclient-3.1. > > When I set client option: > > > > options.setProperty(HTTPConstants.REUSE_HTTP_CLIENT, "true"); > > > > Having two web services invocations from my client I can see that the > HttpClient is really reused when the prop is set. The http connection used > is of type MultiThreadedHttpConnectionManager$HttpConnectionAdapter > > The problem is that here stale connection check is enabled, so when the > check is done as a consequence the connection (and its corresponding socket) > used is closed and a new one is opened. > > In some cases the stale connection check can report a perfectly valid connection as stale. I would strongly recommend disabling it. > > I can read from http://hc.apache.org/httpclient-3.x/preference-api.htmlthat: > > > > "Disabling stale connection check may result in *slight* > *performance*improvement at the risk of getting an I/O error when > executing a request > over a connection that has been closed at the server side." > > > > My general understanding is that in order to have a better performance a > connection should be reused and its socket,too? > > Yes. > > My question is if it is a bad practice to disable stale connection check in > order to reuse the connection and its socket? No, it is not. You just have to make sure your application can react intelligently to I/O exceptions caused by attempts to re-use a stale connection. > Why in commons-httpclient it > is preferred to close and open a new connection: > Only if a connection is believed to have been closed on the other end (is stale). > > > > Where I can read more about the benefit/tradeoff of having stale conn check? > It is recommended to have a reasonable recovery strategy or/and eviction policy for idle connections in place instead of relying on relatively expensive and not always reliable stale connection check. Hope this helps Oleg PS: You may also consider upgrading to HttpClient 4.0-beta1 which has a _much_ better and robust connection management code compared to HttpClient 3.x. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
