[omniORB] orb shutdown hangs in giopServer::deactivate()

[Renzo Tomaselli]

Hi Matej,
    this pattern is similar to what I do. However I noticed that the
blocking connection is owned by a server strand. The client strand seems not
relevant to the blocking.
Now I can reproduce the problem by introducing some delay in servant
destructors.
Basically, my server holds two strands/connections, since the client deals
with parallel threads. I cannot easily reproduce this problem with just one
connection, but nevertheless it appeared after long sessions within only one
connection context.
Then my client holds some refs to server objects which export a "close"
method to deactivate them.
When a server worker gets such a request, we run into next sequence:

- the worker dispatches the operation to the servant, which deactivate
itself.
- a reply is sent to the client, which si free to invoke further operations,
such as closing other server objects.
- if lastInvokationHasCompleted, then object destructor is called. Since
reply has been already sent back, this eventually occurs in parallel among
several objects at the same time.
- the client exits, so that connections to the server are shut down.
- another server worker raises an internal comm. failure
(inputRaiseCommFailure), which is caught by the involved dispatcher and
forces some cleanup (in giopWorker::real_execute()), such as setting the
strand to a DYING status.

All troubles seem due to the parallelism among this worker and other workers
which are removing local identities, which may end up in setting the
connection to a TIMEOUT status.
When things go wrong, we finally endup with a connection which has no more
workers, is dying, but it has pd_refcount = 1, which prevents it to be
removed. Much like if the very last worker terminated without affecting the
connection ref. counter.
I'm full time on this issue by the MSVC debugger, I'll keep the list
informed.
Bye,

Renzo Tomaselli

----- Original Message -----
From: "Matej Kenda" <matej.kenda at hermes.si>
To: "Renzo Tomaselli" <renzo.tomaselli at tecnotp.it>
Cc: "Omniorb list" <omniorb-list at omniorb-support.com>
Sent: Friday, October 17, 2003 11:24 AM
Subject: Re: [omniORB] orb shutdown hangs in giopServer::deactivate()


We have mush simpler case to reproduce this problem:

A servant A is created and its reference is passed as a parameter to
another servant (B) that is running in another ORB (on the same or
another host). Function B_var->Process(A_ptr) is called.

The object reference (A_ptr) is used as a callback within the function
call (B::Process(A_ptr)) on the callee.

After Process() finishes, A is destroyed and the ORB containing A goes
down.
...