(fwd) [Fwd: Communciator 4.02 Imap EXPUNGE problem]

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It can be easily reproduced with Communicator 4.02 and with "Moved
deleted messages into Trash" option off.   Whenever I marked delete with
some messages and tried to expunge (Compress Folders in your
terminology), it found the Communicator will initiate another IMAP
connection to server and FETCH the next message.  While the current one
is sending the EXPUNGE command and waiting for reply.  Two IMAP daemons
contended for the same folder and lead one of them being crashed, the
other one become readonly mode.  Actually, the new connection will be
crashed and return the error messages "IMAP toolkit crash: Lock when
already lock".  I have tried the latest version of UW imapd and found it
will crash the old connection instead and retain the new connection. 
So,  I think it may be implementation dependent, but I'm sure that they
all don't support multiple imapd access on the same folder which use
mbox format.

If you check with others IMAP clients implementation such as PINE or SUN
roam, they all make multiple IMAP connections to server but never SELECT
the same folder at the same time.  So, no access conflict is occurred
and lived peace with each other.

I pretty much sure this problem on 4.02 and also in prior to it.  I put
the sniffer in between the server and client and observed the above
phenomenon.  It's weird you haven't experienced this problem under
extensive test.  It can be easily reproduced either on Win95 or UNIX
client.  John, could you tell us your testing environment and let us
compare?  Or can you confirm whether Communicator wrote codes to make
seperate IMAP connection to server for same folder?  If that's the case,
it is the stem of problem.

Rgds,
Ken Lai

John Friend wrote:
> 
> What crashes?  Can you give us some exact steps to reproduce.  We test
> extensively against the UW server and have not seen this problem.
> 
> --John
> 
> Lai Yiu Fai wrote:
> 
> > It's nice to see Communicator 4.02 now supporting the right IMAP delete
> > model.  However, there's seems to be interoperability problem with UW
> > IMAP.  Though the 4.02 release notes stated has great improvement with
> > UW IMAP server, it's not the case.  I found intermittently the client
> > initiate a new IMAP connection when expunging deleted mail.   The result
> > is two IMAP connections contending for the same folder and crashed one
> > of it.   I see the point that Netscape want to speed up the transcations
> > and parallelize two connections on the same folder.  I think it may work
> > for Netscape IMAP server but not UW IMAP using standard mbox format.   I
> > think that serializing all IMAP commands on same folder is the key point
> > to achieve interoperability with IMAP servers which implement different
> > backend mailbox format.
> >
> > Are there any netscape people aware of this problem?
> >
> > Rgds,
> > =======================================================================
> > Lai Yiu Fai                       |  Tel.:       [phone]
> > Centre of Computing Services      |  Fax.:       [phone]
> >  & Telecommunications             |  E-mail:     [e-mail]
> >                                   |
> > The Hong Kong University of       |  Clear Water Bay,
> > Science & Technology              |  Kowloon, Hong Kong.

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