Slide server hang making collection under locked collection

[Warwick Burrows <wa...@e2open.com>]

Hi,

I'm seeing a serious problem with 2.1b2 where the Slide server is hanging in
the DB2RDBMSAdapter retrieveObject() method() when trying to create a new
collection under a locked collection. The problem doesn't occur when the
parent isn't locked and that seems to be due to the fact that additional
security checks are made when the parent is locked. I have seen this problem
since late last week after having merged in some changes from the 2.1
release branch that equate to the 2.1 b2 baseline. The DB2 client just hangs
and doesn't come back until it times out. The SQL its trying to run is:

	SELECT lu.URI_STRING FROM URI u, URI lu, LINKS l WHERE lu.URI_ID =
l.URI_ID 
	AND l.LINK_TO_ID = u.URI_ID and u.URI_STRING = ?"

Where the "?" is "/actions" in this case.

This is a very commonly executed piece of SQL and is called under a lot of
circumstances. But when called in the course of creating a new collection
under a locked collection then it is being called to fetch the "/actions"
object as part of loading the actions cache (ie. loadActionCache()) from
getActionAggregationClosureImpl() in the SecurityImpl class. It seems to be
the first time that the action cache is being loaded since I started the
Slide server.

When I look at my db2 applications window it says that this thread's status
is "Lock Waiting" and when I force the client thread to complete then the
db2 returns control to Slide with an exception and operation returns to
normal. I don't know what kind of lock it is waiting for. I can reproduce it
with my client, the Slide CLI and the DAVExplorer. Is anyone else seeing
this problem in their deployment, or can anyone suggest why this has started
to happen with 2.1b2?

Thanks,
Warwick

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