On Wed, 2015-05-20 at 13:30 +0000, Mark A. Claassen wrote:
> > 'updated' represents the time of the last update on the client side as
> opposed to 'expiry' which represents keep-alive period
>
> Maybe, but the expire time is then set based on the new value of "updated".
> So, even though no network activity occurred, the new expiration time is set
> as if there was.
> The impact of this is that, after reading a response from the server, any
> processing time that is done between the reading of the data and the
> releasing of the connection is ignored.
You see, the connection release is triggered whenever either of these
events take place.
(1) request is aborted
(2) response is closed
(3) or whenever message content is fully consumed.
So, in the normal course of request execution the expiry time gets
updated not at the time of response closure but at as soon as the
content stream returns -1 (end of stream). That is, pretty much at the
same time as the keep-alive timer starts ticking at the server side.
Oleg
> If the KeepAlive duration is 5 seconds, but some code takes 6 seconds to
> process the results, an expired entry will be placed back into the pool.
> This might not be a big deal, but it defeats the purpose of the check. It
> will also force a stale connection check on a connection that is known to be
> expired.
>
> This is assuming the pattern of:
> Open Connection
> try {
> Send request
> Read response
> Do some initial processing of the response
> }
> finally {
> Close connection
> }
>
> Perhaps the "newExpiry" should be calculated before the "updated" is set to
> the current time?
>
> public synchronized void updateExpiry(final long time, final TimeUnit
> tunit) {
> Args.notNull(tunit, "Time unit");
> this.updated = System.currentTimeMillis();
> final long newExpiry;
> if (time > 0) {
> newExpiry = this.updated + tunit.toMillis(time);
> } else {
> newExpiry = Long.MAX_VALUE;
> }
> this.expiry = Math.min(newExpiry, this.validityDeadline);
> }
>
>
>
> Mark Claassen
> Senior Software Engineer
>
> Donnell Systems, Inc.
> 130 South Main Street
> Leighton Plaza Suite 375
> South Bend, IN 46601
> E-mail: mailto:[email protected]
> Voice: (574)232-3784
> Fax: (574)232-4014
>
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> -----Original Message-----
> From: Oleg Kalnichevski [mailto:[email protected]]
> Sent: Tuesday, May 19, 2015 4:26 AM
> To: HttpClient User Discussion
> Subject: Re: Strange SSL error
>
> On Fri, 2015-05-15 at 16:08 +0000, Mark A. Claassen wrote:
> > Thanks. However, I am still getting the error; even when I do:
> > connectionManager.setValidateAfterInactivity(1);
> >
> > I think this is just because the server can close a keepalive
> > connection at any time. So, if the server decides to kill off the
> > connection in that time slice, the request fails. This most often
> > comes back as a org.apache.http.NoHttpResponseException which the
> > default retry handler will not retry. It seems the only way I can be
> > sure than my connections succeed is to disable keep-alives entirely
> > with a ConnectionReuseStrategy. (Also, Using
> > RequestConfig.setStaleConnectionCheckEnabled(true) seems works better
> > than the setting the setValidateAfterInactivity to 1. I am not sure
> > why.)
> >
> > Question:
> > releaseConnection in PoolingHttpClientConnectionManager calls updateExpiry
> > in PoolEntry. However, this method in PoolEntry also sets the "updated"
> > time. What is "updated" supposed to represent? If it is mainly used to
> > test the keepalive stuff, then it should be updated based on network
> > activity. It doesn’t seem that changing a time to expire value should be
> > counted as "activity" on the connection.
> >
> >
>
> 'updated' represents the time of the last update on the client side as
> opposed to 'expiry' which represents keep-alive period as communicated by the
> server. One might want to close connections after, say, 3 seconds of
> inactivity on client side even though the server's keep-alive is, say, 5
> seconds.
>
> Oleg
>
> >
> > Mark Claassen
> > Senior Software Engineer
> >
> > Donnell Systems, Inc.
> > 130 South Main Street
> > Leighton Plaza Suite 375
> > South Bend, IN 46601
> > E-mail: mailto:[email protected]
> > Voice: (574)232-3784
> > Fax: (574)232-4014
> >
> > -------------------------------------------
> > Confidentiality Notice: OCIESERVICE
> > -------------------------------------------
> > The contents of this e-mail message and any attachments are intended solely
> > for the addressee(s) named in this message. This communication is intended
> > to be and to remain confidential. If you are not the intended recipient of
> > this message, or if this message has been addressed to you in error, please
> > immediately alert the sender by reply e-mail and then delete this message
> > and its attachments. Do not deliver, distribute, copy, disclose the
> > contents or take any action in reliance upon the information contained in
> > the communication or any attachments.
> >
> >
> > -----Original Message-----
> > From: Oleg Kalnichevski [mailto:[email protected]]
> > Sent: Thursday, May 14, 2015 4:38 AM
> > To: HttpClient User Discussion
> > Subject: Re: Strange SSL error
> >
> > On Wed, 2015-05-13 at 20:58 +0000, Mark A. Claassen wrote:
> > > The 4.4.1 code doesn't seem to help.
> > >
> > > I have been able to reproduce the issue more regularly now. It seems to
> > > have to do with keep-alives and if the client takes longer to read the
> > > message than the keep alive value.
> > >
> >
> > Hi Mark
> >
> > Then, it is all very simple. There are several ways to make HttpClient
> > either discard potentially half-closed connections, test them for
> > 'staleness' or automatically recover from NoHttpResponseException.
> >
> >
> > > In my test case I open the connection, read all the data, sleep for a
> > > while, then close the connection.
> > > If my sleep is a bit longer than the keep-alive value, I will get a
> > > org.apache.http.NoHttpResponseException. If my sleep value is larger, I
> > > will get a java.net.SocketException.
> > > (Keep-Alive is 5000 millis. If I sleep for 6000, I will get a
> > > NoHttpResponseException. If I sleep for 11000, I will get a
> > > SocketException.
> > >
> >
> > The default maximum inactivity period used by the pooling connection
> > manager is exactly 5000 ms. Please try reducing this value to, say,
> > 2000 ms
> >
> > ---
> > PoolingHttpClientConnectionManager cm = new
> > PoolingHttpClientConnectionManager();
> > cm.setValidateAfterInactivity(2000);
> >
> > CloseableHttpClient client = HttpClients.custom()
> > .setConnectionManager(cm)
> > .build();
> > ---
> >
> > This should make the problem go away.
> >
> > > If I use the NoConnectionReuseStrategy, the problem goes away.
> > >
> > > Is something set up for my keep alives? I put some breakpoints in
> > > CPool.java. I can see connections being created, but the validate()
> > > method of CPool is never getting called.
> > >
> > > I am curious this part of AbstractConnPool.java. This seems like if the
> > > server invalidated a connection early, the validate check would never
> > > happen.
> > >
> > > } else if (this.validateAfterInactivity > 0) {
> > > if (entry.getUpdated() +
> > > this.validateAfterInactivity <= System.currentTimeMillis()) {
> > > if (!validate(entry)) {
> > > entry.close();
> > > }
> > > }
> > > }
> > > Scenario:
> > > Server sends data.
> > > Client reads packet, processes it for 6 seconds
> > > Server senses that inactivity for 5 seconds, closes connection
> > > Client closes connection and places entry back in the pool
> > > Connection immediately leased to another thread
> > > Time between release and close is almost nothing
> > > Pool releases stale connection.
> > >
> >
> > You can force TTL (total time to live) for connections to avoid this
> > problem
> >
> > ---
> > PoolingHttpClientConnectionManager cm = new
> > PoolingHttpClientConnectionManager(3000, TimeUnit.MILLISECONDS);
> > cm.setValidateAfterInactivity(1000);
> >
> > CloseableHttpClient client = HttpClients.custom()
> > .setConnectionManager(cm)
> > .build();
> > ---
> >
> > Hope this helps
> >
> > Oleg
> >
> >
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