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Posted to users@tomcat.apache.org by "Smith, Mitchell" <mi...@cwc.com> on 2013/08/13 12:43:22 UTC
maxActiveConnections usage
Hi,
I was looking at using the maxActiveConnections in the application context,
what I find is. When I reach the limit, as expected the server will not
create a new session, however does return a http 200 status code.
I am wondering would it be possible for me to change this behavior to
return say a 300 range code to redirect to (in a production environment)
load balancer.
I can see some potential issues with this, like the possibility of an
infinite loop, but for now I am just exploring possible ways to prevent my
tomcat servers becoming overloaded.
Does anyone have any thoughts or ideas for this type of solution?
Regards
--
*Mitchell Smith
*
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Re: maxActiveConnections usage
Posted by Daniel Mikusa <dm...@gopivotal.com>.
On Aug 13, 2013, at 11:37 AM, "Smith, Mitchell" <mi...@cwc.com> wrote:
> Dan,
>
> I am currently developing/testing with the latest version: 7.0.42
Excellent!
> *Note this is different than the configuration you specified above, which
> appears like it's trying to restrict the number of sessions that the
> manager will create*
> Yes, maxActiveSessions is the parameter I am using. As I know the memory
> footprint of a session in the application I have set the parameter to the
> number of sessions I would support per application instance. Thus ensuring
> that an instance is not overloaded by sessions.
Since sessions are your limiting factor, you might want to look at using mod_jk. It has a couple load balancing algorithms based on session count, which might make this easier for you.
See the "method" directive here. http://tomcat.apache.org/connectors-doc/reference/workers.html
> My idea is based on the understanding that I have a fixed user base, and my
> infrastructure is designed to scale for this user base. The issue occurs if
> the LB fails to balance (for what ever reason), the tomcat instance could
> block new sessions and pass the user to a static (helpful) error page
> and/or redirect them back to the base URL of the LB.
You should probably look at what is going on with your load balancer. If a request fails, the load balancer should notice and temporarily take the Tomcat instance out of the load balancing group. Are you using mod_proxy or mod_jk? Can you share your load balancer configuration?
> What I am struggling is the ability to catch the IllegalStateException that
> would be thrown by the Manager, and forward to the error/redirect as a
> result of this.
How are you trying to catch this? In the application? With a filter?
Dan
>
>
>
> On 13 August 2013 15:18, Daniel Mikusa <dm...@gopivotal.com> wrote:
>
>> On Aug 13, 2013, at 9:33 AM, "Smith, Mitchell" <mi...@cwc.com>
>> wrote:
>>
>>> On 13 August 2013 13:24, Daniel Mikusa <dm...@gopivotal.com> wrote:
>>>
>>>> On Aug 13, 2013, at 6:43 AM, "Smith, Mitchell" <mi...@cwc.com>
>>>> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>
>>>> What version of Tomcat are you using? 6.0.x or 7.0.x?
>>>>
>>> Tomcat7
>>
>> Please include the complete version number. There are 42 different Tomcat
>> 7 releases. The more specific you can be the better response you'll get
>> from the list.
>>
>>>
>>>>
>>>>> I was looking at using the maxActiveConnections in the application
>>>> context,
>>>>
>>>> Please include the relevant configuration from your server.xml or
>>>> context.xml file.
>>>>
>>> Context.xml
>>>
>>>> <Context>
>>>>
>>>> <!-- Default set of monitored resources -->
>>>>
>>>> <WatchedResource>WEB-INF/web.xml</WatchedResource>
>>>>
>>>> <!-- Uncomment this to disable session persistence across Tomcat
>>>> restarts -->
>>>>
>>>> <Manager pathname=""
>>>> *maxActiveConnections="150"
>>
>> Are you referring to "maxActiveSessions"?
>>
>> https://tomcat.apache.org/tomcat-7.0-doc/config/manager.html
>>
>>>> */>
>>>> <!-- Uncomment this to enable Comet connection tacking (provides
>> events
>>>> on session expiration as well as webapp lifecycle) -->
>>>> <!--
>>>> <Valve
>>>> className="org.apache.catalina.valves.CometConnectionManagerValve" />
>>>> -->
>>>> </Context>
>>>>
>>>>
>>>>> what I find is. When I reach the limit, as expected the server will not
>>>>> create a new session, however does return a http 200 status code.
>>>>>
>>>>> I am wondering would it be possible for me to change this behavior to
>>>>> return say a 300 range code to redirect to (in a production
>> environment)
>>>>> load balancer.
>>>>>
>>>>> I can see some potential issues with this, like the possibility of an
>>>>> infinite loop, but for now I am just exploring possible ways to prevent
>>>> my
>>>>> tomcat servers becoming overloaded.
>>>>
>>>> How do you have your load balancer setup now? What software / hardware
>>>> are you using? What algorithm is it using to distribute the load?
>>>>
>>> Its an apache httpd server, distributing load using byRequest, with a
>>> redundant fail-over node configured howevr this only works if the tomcat
>>> server fails to accept the initial connection
>>>
>>>>
>>>>>
>>>>> Does anyone have any thoughts or ideas for this type of solution?
>>>>
>>>> Perhaps you need to adjust the load balancer so it's spreading out the
>>>> connections more evenly? Perhaps you need to add another node to handle
>>>> the load?
>>>>
>>>> Its a recent issue, typical user response to a slow application (for
>>> whatever reason) is to open another session, however the jvmRoute is
>> stored
>>> in the browser which forces the 2nd,3rd,4th.... session to the same host.
>>>
>>> We are looking at a application solution to provide a new session without
>>> the jvmRoute in separate tabs, but the ability to reject and redirect a
>>> user (even to a error page) when the server limit we set is reached would
>>> prevent a larger scale outage.
>>
>> You might try "maxConnections" on the HTTP connector.
>>
>> https://tomcat.apache.org/tomcat-7.0-doc/config/http.html
>>
>> or the AJP connector, depending on how your proxy is connecting to Tomcat.
>>
>> https://tomcat.apache.org/tomcat-7.0-doc/config/ajp.html
>>
>> "The maximum number of connections that the server will accept and process
>> at any given time. When this number has been reached, the server will not
>> accept any more connections until the number of connections falls below
>> this value."
>>
>> Note this is different than the configuration you specified above, which
>> appears like it's trying to restrict the number of sessions that the
>> manager will create.
>>
>> Dan
>>
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
>> For additional commands, e-mail: users-help@tomcat.apache.org
>>
>>
>
>
> --
> *Mitchell Smith
> *
> Developer
> *Cable & Wireless Communications*
> Tel: +44 (0) 20 7315 4454
> Mobile: +44 (0) 7921619263
> www.cwc.com
>
> The information contained in this email (and any attachments) is confidential and may be privileged. If you are not the intended recipient
> and have received this email in error, please notify the sender immediately by reply email and delete the message and any attachments.
> If you are not the named addressee, you must not copy, disclose, forward or otherwise use the information contained in this email.
> Cable & Wireless Communications Plc and its affiliates reserve the right to monitor all email communications through their networks to
> ensure regulatory compliance.
>
> Cable & Wireless Communications Plc is a company registered in England & Wales with number:
> 07130199 and offices located at 3rd Floor, 26 Red Lion Square, London WC1R 4HQ
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Re: maxActiveConnections usage
Posted by "Smith, Mitchell" <mi...@cwc.com>.
Dan,
I am currently developing/testing with the latest version: 7.0.42
*Note this is different than the configuration you specified above, which
appears like it's trying to restrict the number of sessions that the
manager will create*
Yes, maxActiveSessions is the parameter I am using. As I know the memory
footprint of a session in the application I have set the parameter to the
number of sessions I would support per application instance. Thus ensuring
that an instance is not overloaded by sessions.
My idea is based on the understanding that I have a fixed user base, and my
infrastructure is designed to scale for this user base. The issue occurs if
the LB fails to balance (for what ever reason), the tomcat instance could
block new sessions and pass the user to a static (helpful) error page
and/or redirect them back to the base URL of the LB.
What I am struggling is the ability to catch the IllegalStateException that
would be thrown by the Manager, and forward to the error/redirect as a
result of this.
-
Mitchell
On 13 August 2013 15:18, Daniel Mikusa <dm...@gopivotal.com> wrote:
> On Aug 13, 2013, at 9:33 AM, "Smith, Mitchell" <mi...@cwc.com>
> wrote:
>
> > On 13 August 2013 13:24, Daniel Mikusa <dm...@gopivotal.com> wrote:
> >
> >> On Aug 13, 2013, at 6:43 AM, "Smith, Mitchell" <mi...@cwc.com>
> >> wrote:
> >>
> >>> Hi,
> >>>
> >>
> >> What version of Tomcat are you using? 6.0.x or 7.0.x?
> >>
> > Tomcat7
>
> Please include the complete version number. There are 42 different Tomcat
> 7 releases. The more specific you can be the better response you'll get
> from the list.
>
> >
> >>
> >>> I was looking at using the maxActiveConnections in the application
> >> context,
> >>
> >> Please include the relevant configuration from your server.xml or
> >> context.xml file.
> >>
> > Context.xml
> >
> >> <Context>
> >>
> >> <!-- Default set of monitored resources -->
> >>
> >> <WatchedResource>WEB-INF/web.xml</WatchedResource>
> >>
> >> <!-- Uncomment this to disable session persistence across Tomcat
> >> restarts -->
> >>
> >> <Manager pathname=""
> >> *maxActiveConnections="150"
>
> Are you referring to "maxActiveSessions"?
>
> https://tomcat.apache.org/tomcat-7.0-doc/config/manager.html
>
> >> */>
> >> <!-- Uncomment this to enable Comet connection tacking (provides
> events
> >> on session expiration as well as webapp lifecycle) -->
> >> <!--
> >> <Valve
> >> className="org.apache.catalina.valves.CometConnectionManagerValve" />
> >> -->
> >> </Context>
> >>
> >>
> >>> what I find is. When I reach the limit, as expected the server will not
> >>> create a new session, however does return a http 200 status code.
> >>>
> >>> I am wondering would it be possible for me to change this behavior to
> >>> return say a 300 range code to redirect to (in a production
> environment)
> >>> load balancer.
> >>>
> >>> I can see some potential issues with this, like the possibility of an
> >>> infinite loop, but for now I am just exploring possible ways to prevent
> >> my
> >>> tomcat servers becoming overloaded.
> >>
> >> How do you have your load balancer setup now? What software / hardware
> >> are you using? What algorithm is it using to distribute the load?
> >>
> > Its an apache httpd server, distributing load using byRequest, with a
> > redundant fail-over node configured howevr this only works if the tomcat
> > server fails to accept the initial connection
> >
> >>
> >>>
> >>> Does anyone have any thoughts or ideas for this type of solution?
> >>
> >> Perhaps you need to adjust the load balancer so it's spreading out the
> >> connections more evenly? Perhaps you need to add another node to handle
> >> the load?
> >>
> >> Its a recent issue, typical user response to a slow application (for
> > whatever reason) is to open another session, however the jvmRoute is
> stored
> > in the browser which forces the 2nd,3rd,4th.... session to the same host.
> >
> > We are looking at a application solution to provide a new session without
> > the jvmRoute in separate tabs, but the ability to reject and redirect a
> > user (even to a error page) when the server limit we set is reached would
> > prevent a larger scale outage.
>
> You might try "maxConnections" on the HTTP connector.
>
> https://tomcat.apache.org/tomcat-7.0-doc/config/http.html
>
> or the AJP connector, depending on how your proxy is connecting to Tomcat.
>
> https://tomcat.apache.org/tomcat-7.0-doc/config/ajp.html
>
> "The maximum number of connections that the server will accept and process
> at any given time. When this number has been reached, the server will not
> accept any more connections until the number of connections falls below
> this value."
>
> Note this is different than the configuration you specified above, which
> appears like it's trying to restrict the number of sessions that the
> manager will create.
>
> Dan
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> For additional commands, e-mail: users-help@tomcat.apache.org
>
>
--
*Mitchell Smith
*
Developer
*Cable & Wireless Communications*
Tel: +44 (0) 20 7315 4454
Mobile: +44 (0) 7921619263
www.cwc.com
The information contained in this email (and any attachments) is confidential and may be privileged. If you are not the intended recipient
and have received this email in error, please notify the sender immediately by reply email and delete the message and any attachments.
If you are not the named addressee, you must not copy, disclose, forward or otherwise use the information contained in this email.
Cable & Wireless Communications Plc and its affiliates reserve the right to monitor all email communications through their networks to
ensure regulatory compliance.
Cable & Wireless Communications Plc is a company registered in England & Wales with number:
07130199 and offices located at 3rd Floor, 26 Red Lion Square, London WC1R 4HQ
Re: maxActiveConnections usage
Posted by Daniel Mikusa <dm...@gopivotal.com>.
On Aug 13, 2013, at 9:33 AM, "Smith, Mitchell" <mi...@cwc.com> wrote:
> On 13 August 2013 13:24, Daniel Mikusa <dm...@gopivotal.com> wrote:
>
>> On Aug 13, 2013, at 6:43 AM, "Smith, Mitchell" <mi...@cwc.com>
>> wrote:
>>
>>> Hi,
>>>
>>
>> What version of Tomcat are you using? 6.0.x or 7.0.x?
>>
> Tomcat7
Please include the complete version number. There are 42 different Tomcat 7 releases. The more specific you can be the better response you'll get from the list.
>
>>
>>> I was looking at using the maxActiveConnections in the application
>> context,
>>
>> Please include the relevant configuration from your server.xml or
>> context.xml file.
>>
> Context.xml
>
>> <Context>
>>
>> <!-- Default set of monitored resources -->
>>
>> <WatchedResource>WEB-INF/web.xml</WatchedResource>
>>
>> <!-- Uncomment this to disable session persistence across Tomcat
>> restarts -->
>>
>> <Manager pathname=""
>> *maxActiveConnections="150"
Are you referring to "maxActiveSessions"?
https://tomcat.apache.org/tomcat-7.0-doc/config/manager.html
>> */>
>> <!-- Uncomment this to enable Comet connection tacking (provides events
>> on session expiration as well as webapp lifecycle) -->
>> <!--
>> <Valve
>> className="org.apache.catalina.valves.CometConnectionManagerValve" />
>> -->
>> </Context>
>>
>>
>>> what I find is. When I reach the limit, as expected the server will not
>>> create a new session, however does return a http 200 status code.
>>>
>>> I am wondering would it be possible for me to change this behavior to
>>> return say a 300 range code to redirect to (in a production environment)
>>> load balancer.
>>>
>>> I can see some potential issues with this, like the possibility of an
>>> infinite loop, but for now I am just exploring possible ways to prevent
>> my
>>> tomcat servers becoming overloaded.
>>
>> How do you have your load balancer setup now? What software / hardware
>> are you using? What algorithm is it using to distribute the load?
>>
> Its an apache httpd server, distributing load using byRequest, with a
> redundant fail-over node configured howevr this only works if the tomcat
> server fails to accept the initial connection
>
>>
>>>
>>> Does anyone have any thoughts or ideas for this type of solution?
>>
>> Perhaps you need to adjust the load balancer so it's spreading out the
>> connections more evenly? Perhaps you need to add another node to handle
>> the load?
>>
>> Its a recent issue, typical user response to a slow application (for
> whatever reason) is to open another session, however the jvmRoute is stored
> in the browser which forces the 2nd,3rd,4th.... session to the same host.
>
> We are looking at a application solution to provide a new session without
> the jvmRoute in separate tabs, but the ability to reject and redirect a
> user (even to a error page) when the server limit we set is reached would
> prevent a larger scale outage.
You might try "maxConnections" on the HTTP connector.
https://tomcat.apache.org/tomcat-7.0-doc/config/http.html
or the AJP connector, depending on how your proxy is connecting to Tomcat.
https://tomcat.apache.org/tomcat-7.0-doc/config/ajp.html
"The maximum number of connections that the server will accept and process at any given time. When this number has been reached, the server will not accept any more connections until the number of connections falls below this value."
Note this is different than the configuration you specified above, which appears like it's trying to restrict the number of sessions that the manager will create.
Dan
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Re: maxActiveConnections usage
Posted by "Smith, Mitchell" <mi...@cwc.com>.
On 13 August 2013 13:24, Daniel Mikusa <dm...@gopivotal.com> wrote:
> On Aug 13, 2013, at 6:43 AM, "Smith, Mitchell" <mi...@cwc.com>
> wrote:
>
> > Hi,
> >
>
> What version of Tomcat are you using? 6.0.x or 7.0.x?
>
Tomcat7
>
> > I was looking at using the maxActiveConnections in the application
> context,
>
> Please include the relevant configuration from your server.xml or
> context.xml file.
>
Context.xml
> <Context>
>
> <!-- Default set of monitored resources -->
>
> <WatchedResource>WEB-INF/web.xml</WatchedResource>
>
> <!-- Uncomment this to disable session persistence across Tomcat
> restarts -->
>
> <Manager pathname=""
> *maxActiveConnections="150"
> */>
> <!-- Uncomment this to enable Comet connection tacking (provides events
> on session expiration as well as webapp lifecycle) -->
> <!--
> <Valve
> className="org.apache.catalina.valves.CometConnectionManagerValve" />
> -->
> </Context>
>
>
> > what I find is. When I reach the limit, as expected the server will not
> > create a new session, however does return a http 200 status code.
> >
> > I am wondering would it be possible for me to change this behavior to
> > return say a 300 range code to redirect to (in a production environment)
> > load balancer.
> >
> > I can see some potential issues with this, like the possibility of an
> > infinite loop, but for now I am just exploring possible ways to prevent
> my
> > tomcat servers becoming overloaded.
>
> How do you have your load balancer setup now? What software / hardware
> are you using? What algorithm is it using to distribute the load?
>
Its an apache httpd server, distributing load using byRequest, with a
redundant fail-over node configured howevr this only works if the tomcat
server fails to accept the initial connection
>
> >
> > Does anyone have any thoughts or ideas for this type of solution?
>
> Perhaps you need to adjust the load balancer so it's spreading out the
> connections more evenly? Perhaps you need to add another node to handle
> the load?
>
> Its a recent issue, typical user response to a slow application (for
whatever reason) is to open another session, however the jvmRoute is stored
in the browser which forces the 2nd,3rd,4th.... session to the same host.
We are looking at a application solution to provide a new session without
the jvmRoute in separate tabs, but the ability to reject and redirect a
user (even to a error page) when the server limit we set is reached would
prevent a larger scale outage.
Dan
>
>
> >
> > Regards
> > --
> > *Mitchell Smith
> > *
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> For additional commands, e-mail: users-help@tomcat.apache.org
>
>
The information contained in this email (and any attachments) is confidential and may be privileged. If you are not the intended recipient
and have received this email in error, please notify the sender immediately by reply email and delete the message and any attachments.
If you are not the named addressee, you must not copy, disclose, forward or otherwise use the information contained in this email.
Cable & Wireless Communications Plc and its affiliates reserve the right to monitor all email communications through their networks to
ensure regulatory compliance.
Cable & Wireless Communications Plc is a company registered in England & Wales with number:
07130199 and offices located at 3rd Floor, 26 Red Lion Square, London WC1R 4HQ
Re: maxActiveConnections usage
Posted by Daniel Mikusa <dm...@gopivotal.com>.
On Aug 13, 2013, at 6:43 AM, "Smith, Mitchell" <mi...@cwc.com> wrote:
> Hi,
>
What version of Tomcat are you using? 6.0.x or 7.0.x?
> I was looking at using the maxActiveConnections in the application context,
Please include the relevant configuration from your server.xml or context.xml file.
> what I find is. When I reach the limit, as expected the server will not
> create a new session, however does return a http 200 status code.
>
> I am wondering would it be possible for me to change this behavior to
> return say a 300 range code to redirect to (in a production environment)
> load balancer.
>
> I can see some potential issues with this, like the possibility of an
> infinite loop, but for now I am just exploring possible ways to prevent my
> tomcat servers becoming overloaded.
How do you have your load balancer setup now? What software / hardware are you using? What algorithm is it using to distribute the load?
>
> Does anyone have any thoughts or ideas for this type of solution?
Perhaps you need to adjust the load balancer so it's spreading out the connections more evenly? Perhaps you need to add another node to handle the load?
Dan
>
> Regards
> --
> *Mitchell Smith
> *
>
> The information contained in this email (and any attachments) is confidential and may be privileged. If you are not the intended recipient
> and have received this email in error, please notify the sender immediately by reply email and delete the message and any attachments.
> If you are not the named addressee, you must not copy, disclose, forward or otherwise use the information contained in this email.
> Cable & Wireless Communications Plc and its affiliates reserve the right to monitor all email communications through their networks to
> ensure regulatory compliance.
>
> Cable & Wireless Communications Plc is a company registered in England & Wales with number:
> 07130199 and offices located at 3rd Floor, 26 Red Lion Square, London WC1R 4HQ
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