On 03/12/2010 05:36 PM, Ron Bessems wrote:
Ah, looks like this is fixed on the trunk already.
Yes, I believe so.
Though looking at that code it fails to throw an error if
all sessions have been used and simply silently goes on.
That's a bug, well spotted. I've raised
https://issues.apache.org/jira/browse/QPID-2448
- Ron
Friday, March 12, 2010, 2:28:28 PM, you wrote:
Okay, I've found the bug. It's a wrap around issue.
void ConnectionImpl::addSession(const
boost::shared_ptr<SessionImpl>& session, uint16_t channel)
{
Mutex::ScopedLock l(lock);
session->setChannel(channel ? channel : nextChannel++);
boost::weak_ptr<SessionImpl>& s = sessions[session->getChannel()];
boost::shared_ptr<SessionImpl> ss = s.lock();
if (ss) {
throw SessionBusyException(QPID_MSG("Channel "<<
ss->getChannel()<< " attached to "<< ss->getId()));
}
s = session;
}
At the time of the error this is the value of some of the variables:
channel = 0
nextChannel = 3
session->getChannel() = 2
sessions [6]((0,{px=0x083c8508 pn={...} }),(1,{px=0x0839b7a8
pn={...} }),(2,{px=0x033f3bb0 pn={...} }),(65533,{px=0x083c2008
pn={...} }),(65534,{px=0x08394c00 pn={...} }),(65535,{px=0x083cd368 pn={...} }))
Note how channel 2 is actually already in use! That should not be as
our nextChannel integer should point at a free channel. Sadly that is
try until nextChannel wraps around, which will happen eventually, just
in my program is ends up being sooner rather than later. I've
rewritten part addSession.
void ConnectionImpl::addSession(const
boost::shared_ptr<SessionImpl>& session, uint16_t channel)
{
Mutex::ScopedLock l(lock);
if ( channel == 0 )
{
for (uint16_t c = nextChannel; c != (nextChannel-1); c++ )
{
boost::weak_ptr<SessionImpl>& s = sessions[c];
boost::shared_ptr<SessionImpl> ss = s.lock();
if ( !ss )
{
session->setChannel(c);
nextChannel = c + 1;
s = session;
return;
}
}
throw SessionBusyException(QPID_MSG("All channels in use"));
}
else
{
session->setChannel(channel);
boost::weak_ptr<SessionImpl>& s =
sessions[session->getChannel()];
boost::shared_ptr<SessionImpl> ss = s.lock();
if (ss) throw
SessionBusyException(QPID_MSG("Channel "<< ss->getChannel()<< " attached to "<<
ss->getId()));
s = session;
}
}
I'll submit a bug report as well.
- Ron
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Project: http://qpid.apache.org
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