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From Helena Carbajo <helenacarbajoolm...@gmail.com>
Subject Re: tomcat 8.5.23 can not modify maxconcurrentstream setting
Date Fri, 01 Mar 2019 12:35:42 GMT
> From what I see in the test a STREAM_REFUSED is returned when a the
maxConcurrentStream  is set to one. Yet I'd like to understand how this
value is changed internally. I think >the only difference with my code is
the call to the method doHttpUpgrade() which seems to send a GET for
upgrade. Does this perform the actual upgrade of the settings? If this >is
the case where is it implemented?



>Http2UpgradeHandler (which represents an HTTP/2 connection) sets the
maximum concurrent stream value when the connection is created:



>https://github.com/apache/tomcat/blob/master/java/org/apache/coyote/http2/Http2UpgradeHandler.java#L156
<https://github.com/apache/tomcat/blob/master/java/org/apache/coyote/http2/Http2UpgradeHandler.java#L156>



>This means if the value set on the protocol is changed dynamically, the
new value takes effect for all subsequent connections.



>The setting is communicated to the client as part of the connection
preface.



>https://github.com/apache/tomcat/blob/master/java/org/apache/coyote/http2/Http2UpgradeHandler.java#L229
<https://github.com/apache/tomcat/blob/master/java/org/apache/coyote/http2/Http2UpgradeHandler.java#L229>



>Well-behaved clients will respect this setting but Tomcat checks the limit
every time a new stream is created.



>https://github.com/apache/tomcat/blob/master/java/org/apache/coyote/http2/Http2UpgradeHandler.java#L1333
<https://github.com/apache/tomcat/blob/master/java/org/apache/coyote/http2/Http2UpgradeHandler.java#L1333>



>You may find enabling Tomcat's debug logging for HTTP/2 instructive.



>Mark



Thanks. I finally understood how it all works.


Helena


El vie., 1 mar. 2019 a las 10:44, Mark Thomas (<markt@apache.org>) escribió:

> On 27/02/2019 08:37, Helena Carbajo wrote:
> >>> See
> >>>
> https://github.com/apache/tomcat/blob/8.5.x/test/org/apache/coyote/http2/TestHttp2Section_5_1.java#L174
> >
> > From what I see in the test a STREAM_REFUSED is returned when a the
> maxConcurrentStream  is set to one. Yet I'd like to understand how this
> value is changed internally. I think the only difference with my code is
> the call to the method doHttpUpgrade() which seems to send a GET for
> upgrade. Does this perform the actual upgrade of the settings? If this is
> the case where is it implemented?
>
> Http2UpgradeHandler (which represents an HTTP/2 connection) sets the
> maximum concurrent stream value when the connection is created:
>
>
> https://github.com/apache/tomcat/blob/master/java/org/apache/coyote/http2/Http2UpgradeHandler.java#L156
>
> This means if the value set on the protocol is changed dynamically, the
> new value takes effect for all subsequent connections.
>
> The setting is communicated to the client as part of the connection
> preface.
>
>
> https://github.com/apache/tomcat/blob/master/java/org/apache/coyote/http2/Http2UpgradeHandler.java#L229
>
> Well-behaved clients will respect this setting but Tomcat checks the
> limit every time a new stream is created.
>
>
> https://github.com/apache/tomcat/blob/master/java/org/apache/coyote/http2/Http2UpgradeHandler.java#L1333
>
> You may find enabling Tomcat's debug logging for HTTP/2 instructive.
>
> Mark
>
>
> >
> > -----Original Message-----
> > From: Mark Thomas <markt@apache.org>
> > Sent: martes, 26 de febrero de 2019 13:45
> > To: users@tomcat.apache.org
> > Subject: Re: tomcat 8.5.23 can not modify maxconcurrentstream setting
> >
> > See
> >
> https://github.com/apache/tomcat/blob/8.5.x/test/org/apache/coyote/http2/TestHttp2Section_5_1.java#L174
> >
> > Mark
> >
> >
> > On 26/02/2019 11:01, Helena Carbajo wrote:
> >> I'm trying to modify the value of MaxConcurrentStream for the tomcat
> server in order to check that it returns a STREAM_REFUSED when the client
> uses more streams, but I don't manage to change the default unlimited value.
> >>
> >> I've been inspecting the tomcat server code with a debugger and I saw
> it enters the method protected synchronized void set(Setting setting, Long
> value)  from the org.apache.coyote.http2.ConnectionSettingsLocal.java class
> to change the value for maxConcurrentStream. Yet, if I'm not wrong, it only
> modifies the pending hashSet not the current one, which is the one that is
> checked later on to determine if it is lower than the clients' active
> streams and therefore send the  STREAM_REFUSED code.
> >>
> >>
> >>
> >> I'm not sure if  I'm not modifying the value correctly. I use the
> Http2Protocol's method setMaxConcurrentStreams to set the value and then
> add the Http2Protocol to the connector(addUpgradeProtocol).
> >>
> >>
> >>
> >> I'd be grateful if someone could give me a hint of what is going on or
> what I'm doing wrong. Thank you!
> >>
> >>
> >
> >
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