Any way to synchronize on session variables

[xmly]

Hi, 

 The sample code is like this: 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(3000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

 But return method gets too many requests. So several threads are trying to get and delete session.key which causes race problem. 

 Is there any method could fix this problem?  

 Thank you so much.

Best,

Gavin 

   

[lucastex]

Why are you trying to synchronize on a session var?

each visitor will have his own session, so, is this really necessary?

[]s,

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 10:43 PM, Gavin Yue <[hidden email]> wrote:

Hi, 

 The sample code is like this: 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(3000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

 But return method gets too many requests. So several threads are trying to get and delete session.key which causes race problem. 

 Is there any method could fix this problem?  

 Thank you so much.

Best,

Gavin 

   

[xmly]

For example, user clicks the button twice pretty quickly. 

In our case, it is a return call from paypal. Paypal quickly called method several times. 

On Wed, Jun 22, 2011 at 10:38 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

Why are you trying to synchronize on a session var?

each visitor will have his own session, so, is this really necessary?

[]s,

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 10:43 PM, Gavin Yue <[hidden email]> wrote:

Hi, 

 The sample code is like this: 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(3000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

 But return method gets too many requests. So several threads are trying to get and delete session.key which causes race problem. 

 Is there any method could fix this problem?  

 Thank you so much.

Best,

Gavin 

   

[lucastex]

You can use default grails utility to handle this:

http://grails.org/doc/latest/guide/single.html#6.1.11 Handling Duplicate Form Submissions

It works pretty well for us, and protect our app from these cases (frenetic users clicking around)

[]s, 

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 11:43 PM, Gavin Yue <[hidden email]> wrote:

For example, user clicks the button twice pretty quickly. 

In our case, it is a return call from paypal. Paypal quickly called method several times. 

On Wed, Jun 22, 2011 at 10:38 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

Why are you trying to synchronize on a session var?

each visitor will have his own session, so, is this really necessary?

[]s,

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 10:43 PM, Gavin Yue <[hidden email]> wrote:

Hi, 

 The sample code is like this: 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(3000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

 But return method gets too many requests. So several threads are trying to get and delete session.key which causes race problem. 

 Is there any method could fix this problem?  

 Thank you so much.

Best,

Gavin 

   

[xmly]

Thank you. But in our case, it is not form submission. It is just http get. 

It is like you create two thread(request) and each of them try to read and modify one variable in the session. 

On Wed, Jun 22, 2011 at 10:50 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

You can use default grails utility to handle this:

http://grails.org/doc/latest/guide/single.html#6.1.11 Handling Duplicate Form Submissions

It works pretty well for us, and protect our app from these cases (frenetic users clicking around)

[]s, 

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 11:43 PM, Gavin Yue <[hidden email]> wrote:

For example, user clicks the button twice pretty quickly. 

In our case, it is a return call from paypal. Paypal quickly called method several times. 

On Wed, Jun 22, 2011 at 10:38 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

Why are you trying to synchronize on a session var?

each visitor will have his own session, so, is this really necessary?

[]s,

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 10:43 PM, Gavin Yue <[hidden email]> wrote:

Hi, 

 The sample code is like this: 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(3000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

 But return method gets too many requests. So several threads are trying to get and delete session.key which causes race problem. 

 Is there any method could fix this problem?  

 Thank you so much.

Best,

Gavin 

   

[lucastex]

Can't you work on some similar mechanism?

You can mark your session with a 'running' attribute, and remove it when paypal returns the response.

Further requests would check the 'running' attirbute before making a new request.

[]s,

 
Lucas Teixeira

twitter.com/lucastex

On Thu, Jun 23, 2011 at 12:12 AM, Gavin Yue <[hidden email]> wrote:

Thank you. But in our case, it is not form submission. It is just http get. 

It is like you create two thread(request) and each of them try to read and modify one variable in the session. 

On Wed, Jun 22, 2011 at 10:50 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

You can use default grails utility to handle this:

http://grails.org/doc/latest/guide/single.html#6.1.11 Handling Duplicate Form Submissions

It works pretty well for us, and protect our app from these cases (frenetic users clicking around)

[]s, 

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 11:43 PM, Gavin Yue <[hidden email]> wrote:

For example, user clicks the button twice pretty quickly. 

In our case, it is a return call from paypal. Paypal quickly called method several times. 

On Wed, Jun 22, 2011 at 10:38 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

Why are you trying to synchronize on a session var?

each visitor will have his own session, so, is this really necessary?

[]s,

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 10:43 PM, Gavin Yue <[hidden email]> wrote:

Hi, 

 The sample code is like this: 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(3000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

 But return method gets too many requests. So several threads are trying to get and delete session.key which causes race problem. 

 Is there any method could fix this problem?  

 Thank you so much.

Best,

Gavin 

   

[xmly]

This is the sample code : 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(5000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

I removed the session.key variable. But another thread is too fast and the current thread sleeps for 5 seconds. 

On Wed, Jun 22, 2011 at 11:20 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

Can't you work on some similar mechanism?

You can mark your session with a 'running' attribute, and remove it when paypal returns the response.

Further requests would check the 'running' attirbute before making a new request.

[]s,

 
Lucas Teixeira

twitter.com/lucastex

On Thu, Jun 23, 2011 at 12:12 AM, Gavin Yue <[hidden email]> wrote:

Thank you. But in our case, it is not form submission. It is just http get. 

It is like you create two thread(request) and each of them try to read and modify one variable in the session. 

On Wed, Jun 22, 2011 at 10:50 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

You can use default grails utility to handle this:

http://grails.org/doc/latest/guide/single.html#6.1.11 Handling Duplicate Form Submissions

It works pretty well for us, and protect our app from these cases (frenetic users clicking around)

[]s, 

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 11:43 PM, Gavin Yue <[hidden email]> wrote:

For example, user clicks the button twice pretty quickly. 

In our case, it is a return call from paypal. Paypal quickly called method several times. 

On Wed, Jun 22, 2011 at 10:38 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

Why are you trying to synchronize on a session var?

each visitor will have his own session, so, is this really necessary?

[]s,

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 10:43 PM, Gavin Yue <[hidden email]> wrote:

Hi, 

 The sample code is like this: 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(3000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

 But return method gets too many requests. So several threads are trying to get and delete session.key which causes race problem. 

 Is there any method could fix this problem?  

 Thank you so much.

Best,

Gavin 

   

[sd]

Doing a grails compile on an application that is configured with an inline plugin gives a unresolved dependency on that plugin.

This had worked fine with 1.3.7 but after upgrading it now produces this error.

Anyone else encounter this?

[Adrian Roston]

Do what most merchants do, disable the button and tell them not to refresh the page.    

From: Gavin Yue <[hidden email]>
Reply-To: <[hidden email]>
Date: Wed, 22 Jun 2011 22:43:19 -0400
To: <[hidden email]>
Subject: Re: [grails-user] Any way to synchronize on session variables

For example, user clicks the button twice pretty quickly. 

In our case, it is a return call from paypal. Paypal quickly called method several times. 

On Wed, Jun 22, 2011 at 10:38 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

Why are you trying to synchronize on a session var?

each visitor will have his own session, so, is this really necessary?

[]s,

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 10:43 PM, Gavin Yue <[hidden email]> wrote:

Hi, 

 The sample code is like this: 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(3000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

 But return method gets too many requests. So several threads are trying to get and delete session.key which causes race problem. 

 Is there any method could fix this problem?  

 Thank you so much.

Best,

Gavin 

   

[Mohamed Seifeddine]

What about something along the lines: 

if ( !session.paymentInProgress ) {

 session.paymentInProgress = true

  // Do something

  session..paymentInProgress = false

}

else { ... }

/ Mohamed

On Thu, Jun 23, 2011 at 9:28 AM, Adrian Roston <[hidden email]> wrote:

Do what most merchants do, disable the button and tell them not to refresh the page.    

From: Gavin Yue <[hidden email]>
Reply-To: <[hidden email]>
Date: Wed, 22 Jun 2011 22:43:19 -0400
To: <[hidden email]>
Subject: Re: [grails-user] Any way to synchronize on session variables

For example, user clicks the button twice pretty quickly. 

In our case, it is a return call from paypal. Paypal quickly called method several times. 

On Wed, Jun 22, 2011 at 10:38 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

Why are you trying to synchronize on a session var?

each visitor will have his own session, so, is this really necessary?

[]s,

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 10:43 PM, Gavin Yue <[hidden email]> wrote:

Hi, 

 The sample code is like this: 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(3000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

 But return method gets too many requests. So several threads are trying to get and delete session.key which causes race problem. 

 Is there any method could fix this problem?  

 Thank you so much.

Best,

Gavin 

   

[xmly]

I thought this method as well. But in the very extreme cases, what if two threads are both trying to set: session.paymentInProgress = true ?  Because they both check  session.paymentInProgress at the same time and find it is null. 

On Thu, Jun 23, 2011 at 7:15 AM, Mohamed Seifeddine <[hidden email]> wrote:

What about something along the lines: 

if ( !session.paymentInProgress ) {

 session.paymentInProgress = true

  // Do something

  session..paymentInProgress = false

}

else { ... }

/ Mohamed

On Thu, Jun 23, 2011 at 9:28 AM, Adrian Roston <[hidden email]> wrote:

Do what most merchants do, disable the button and tell them not to refresh the page.    

From: Gavin Yue <[hidden email]>
Reply-To: <[hidden email]>
Date: Wed, 22 Jun 2011 22:43:19 -0400
To: <[hidden email]>
Subject: Re: [grails-user] Any way to synchronize on session variables

For example, user clicks the button twice pretty quickly. 

In our case, it is a return call from paypal. Paypal quickly called method several times. 

On Wed, Jun 22, 2011 at 10:38 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

Why are you trying to synchronize on a session var?

each visitor will have his own session, so, is this really necessary?

[]s,

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 10:43 PM, Gavin Yue <[hidden email]> wrote:

Hi, 

 The sample code is like this: 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(3000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

 But return method gets too many requests. So several threads are trying to get and delete session.key which causes race problem. 

 Is there any method could fix this problem?  

 Thank you so much.

Best,

Gavin 

   

[jstell]

Maybe extreme approach: How about putting a session-specific token in the DB and doing a pessimistic lock on it?

Jason

On Thu, Jun 23, 2011 at 10:08 AM, Gavin Yue <[hidden email]> wrote:

I thought this method as well. But in the very extreme cases, what if two threads are both trying to set: session.paymentInProgress = true ?  Because they both check  session.paymentInProgress at the same time and find it is null. 

On Thu, Jun 23, 2011 at 7:15 AM, Mohamed Seifeddine <[hidden email]> wrote:

What about something along the lines: 

if ( !session.paymentInProgress ) {

 session.paymentInProgress = true

  // Do something

  session..paymentInProgress = false

}

else { ... }

/ Mohamed

On Thu, Jun 23, 2011 at 9:28 AM, Adrian Roston <[hidden email]> wrote:

Do what most merchants do, disable the button and tell them not to refresh the page.    

From: Gavin Yue <[hidden email]>
Reply-To: <[hidden email]>
Date: Wed, 22 Jun 2011 22:43:19 -0400
To: <[hidden email]>
Subject: Re: [grails-user] Any way to synchronize on session variables

For example, user clicks the button twice pretty quickly. 

In our case, it is a return call from paypal. Paypal quickly called method several times. 

On Wed, Jun 22, 2011 at 10:38 PM, Lucas F. A. Teixeira <[hidden email]> wrote:

Why are you trying to synchronize on a session var?

each visitor will have his own session, so, is this really necessary?

[]s,

Lucas Teixeira

twitter.com/lucastex

On Wed, Jun 22, 2011 at 10:43 PM, Gavin Yue <[hidden email]> wrote:

Hi, 

 The sample code is like this: 

  Class AController { 

  def return = { 

    if(session.key) {

     sleep(3000)

     // use the session.key do something

     

     remove(session.key)

    }

    }

  }

 But return method gets too many requests. So several threads are trying to get and delete session.key which causes race problem. 

 Is there any method could fix this problem?  

 Thank you so much.

Best,

Gavin 

   

[Graeme Rocher-4]

Please raise a JIRA with an example

Cheers

On Thu, Jun 23, 2011 at 7:53 AM,  <[hidden email]> wrote:
> Doing a grails compile on an application that is configured with an inline
> plugin gives a unresolved dependency on that plugin.
>
> This had worked fine with 1.3.7 but after upgrading it now produces this
> error.
>
> Anyone else encounter this?
>



--
Graeme Rocher
Grails Project Lead
SpringSource - A Division of VMware
http://www.springsource.com

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