RE: Clear user session
Is this a re-post? I saw some pal posted a very good explaination why you
cann't do it. Are you not reading those posts?.
My suggestion is to use session.removeAttribute(attr_name) or simply set
those attributes to null.
-Original Message-
From: shyam [mailto:[EMAIL PROTECTED]
Sent: June 6, 2003 2:40 PM
To: Tomcat Users List
Subject: Clear user session
Hi All,
I just moved my webapp from jrun to tomcat. I have a method which clears the
user session. The code snippet is
Enumeration session_var = session.getAttributeNames();
while(session_var.hasMoreElements())
{
String key=(String)session_var.nextElement();
I am getting an error here and the exception is
java.util.ConcurrentModificationException at
java.util.HashMap$HashIterator.nextEntry
How can I resolve this error.
Thanks a lot in advance
shyam
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Re: Clear user session
Howdy,
Something else is modifying the session (adding/removing attributes or
otherwise modifying the backing collection of your session_var enumeration)
while you're iterating through it.
> while(session_var.hasMoreElements())
> {
> String key=(String)session_var.nextElement();
You need to make the above code synchronized on the session. This may not be
as trivial as it sounds: for example, it might be impossible if your
environment is clustered.
Alternative options include doing this on session passivation or destruction
(probably the former), using the appopriate listener.
Why are you clearing all the attributes instead of a specific one?
Yoav Shapira
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RE: clear user session
Simple set the element value to null instead of removing it.
-Original Message-
From: Shyama Gavulla [mailto:[EMAIL PROTECTED]
Sent: June 6, 2003 3:28 PM
To: [EMAIL PROTECTED]
Subject: Re: clear user session
--
Hi,
Thanks for the reply. As you have said I was trying to make changes while
iterating over the loop. I cant do session.invalidate as I want the session
to be valid but certain keys to be removed. I am using tomcat 4.1 and the
same code in Jrun works fine . No errors. I wonder how that works fine.
Anyways I have a fix for that . I am trying to implement it . Thanks a lot
Shyam
- Original Message -
From: "Tim Funk" <[EMAIL PROTECTED]>
To: "Tomcat Users List" <[EMAIL PROTECTED]>
Sent: Friday, June 06, 2003 3:19 PM
Subject: Re: Clear User Session
> Depending on who you talk to its a bug or not a bug in tomcat.
>
> session.getAttributeNames() returns an Enumeration. Under the covers, the
> Enumeration is actually a facade around an Iterator. Iterators are
fail-fast
> so if you are enumerating through session attributes and make changes, you
> get the error as you have described.
>
> The arguement is: is Enumeration allowed to be fail-fast?
>
> In the meantime, 4.1 and 5 were patched to not make the Enumerator
> originating from session.getAttributeNames be fail-fast.
>
>
> As an aside - if you need to clear out a session: session.invalidate() is
> much easier.
>
> -Tim
>
> Shyama Gavulla wrote:
> > Hi All,
> >
> > I just moved my webapp from jrun to tomcat. I have a method which
clears the
> > user session. The code snippet is
> >
> > Enumeration session_var = session.getAttributeNames();
> >
> > while(session_var.hasMoreElements())
> > {
> > String key=(String)session_var.nextElement();
> >
> > I am getting an error here and the exception is
> >
> > java.util.ConcurrentModificationException at
> > java.util.HashMap$HashIterator.nextEntry
> >
> > How can I resolve this error.
> >
> > Thanks a lot in advance
> > shyam
>
>
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> For additional commands, e-mail: [EMAIL PROTECTED]
>
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Re: clear user session
--
Hi,
Thanks for the reply. As you have said I was trying to make changes while
iterating over the loop. I cant do session.invalidate as I want the session
to be valid but certain keys to be removed. I am using tomcat 4.1 and the
same code in Jrun works fine . No errors. I wonder how that works fine.
Anyways I have a fix for that . I am trying to implement it . Thanks a lot
Shyam
- Original Message -
From: "Tim Funk" <[EMAIL PROTECTED]>
To: "Tomcat Users List" <[EMAIL PROTECTED]>
Sent: Friday, June 06, 2003 3:19 PM
Subject: Re: Clear User Session
> Depending on who you talk to its a bug or not a bug in tomcat.
>
> session.getAttributeNames() returns an Enumeration. Under the covers, the
> Enumeration is actually a facade around an Iterator. Iterators are
fail-fast
> so if you are enumerating through session attributes and make changes, you
> get the error as you have described.
>
> The arguement is: is Enumeration allowed to be fail-fast?
>
> In the meantime, 4.1 and 5 were patched to not make the Enumerator
> originating from session.getAttributeNames be fail-fast.
>
>
> As an aside - if you need to clear out a session: session.invalidate() is
> much easier.
>
> -Tim
>
> Shyama Gavulla wrote:
> > Hi All,
> >
> > I just moved my webapp from jrun to tomcat. I have a method which
clears the
> > user session. The code snippet is
> >
> > Enumeration session_var = session.getAttributeNames();
> >
> > while(session_var.hasMoreElements())
> > {
> > String key=(String)session_var.nextElement();
> >
> > I am getting an error here and the exception is
> >
> > java.util.ConcurrentModificationException at
> > java.util.HashMap$HashIterator.nextEntry
> >
> > How can I resolve this error.
> >
> > Thanks a lot in advance
> > shyam
>
>
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> To unsubscribe, e-mail: [EMAIL PROTECTED]
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>
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Re: Clear User Session
Depending on who you talk to its a bug or not a bug in tomcat.
session.getAttributeNames() returns an Enumeration. Under the covers, the
Enumeration is actually a facade around an Iterator. Iterators are fail-fast
so if you are enumerating through session attributes and make changes, you
get the error as you have described.
The arguement is: is Enumeration allowed to be fail-fast?
In the meantime, 4.1 and 5 were patched to not make the Enumerator
originating from session.getAttributeNames be fail-fast.
As an aside - if you need to clear out a session: session.invalidate() is
much easier.
-Tim
Shyama Gavulla wrote:
> Hi All,
>
> I just moved my webapp from jrun to tomcat. I have a method which clears the
> user session. The code snippet is
>
> Enumeration session_var = session.getAttributeNames();
>
> while(session_var.hasMoreElements())
> {
> String key=(String)session_var.nextElement();
>
> I am getting an error here and the exception is
>
> java.util.ConcurrentModificationException at
> java.util.HashMap$HashIterator.nextEntry
>
> How can I resolve this error.
>
> Thanks a lot in advance
> shyam
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