Re: Fixed deadlock in GridDhtAtomicCache (Alex G. your review is needed)

[Denis Magda]

Andrey Gura,

Could you put the info on the errors you observed with cache read 
operations in the ticket below?

--
Denis

On 8/10/2015 3:13 PM, Denis Magda wrote:
What do you mean under the cleanup on a higher level?

Do you consider setting all cache context references to null when 
required letting a garbage collector to deallocate context's internals 
when it's time for that?

In any case I've created a ticker where we can put all the useful 
thoughts/ideas that should help an implementor.
https://issues.apache.org/jira/browse/IGNITE-1221

--
Denis

On 8/5/2015 5:48 PM, Yakov Zhdanov wrote:
Guys, what about not invalidating cache contexts on stop? Let's 
cleanup on
higher level.

--Yakov

2015-08-04 22:48 GMT+03:00 Denis Magda <dma...@gridgain.com>:

Alex, thanks for the review!

Sure, this is just a local fix.
Recently I've detected and fixed several issues in TCP communication 
SPI
that happened because of invalidated cache context. In addition, Andrey
Gura mentioned that periodically he reproduces hangs in cache get
operations that most likely to happen because of invalidated cache 
context
as well.

Seems that it's time to fix the situation with invalidated cache 
context
globally. I'll create a task in JIRA in several days when return from a
short vacation putting extensive details. Then someone from the 
community
or me will have a chance to makes his/her hands dirty with this :)

As for this deadlock I'll merge that changes in any case because we 
need to
have them in the code to omit other RuntimeExceptions that may happen
because of any other reason. The threads that led to the deadlock were
threads from partitions supply pool or some internal workers pool.

Regards,
Denis

On 4 авг. 2015 г., at 22:09, Alexey Goncharuk 
<alexey.goncha...@gmail.com>
wrote:

The change by itself looks right and can be merged, however I do not 
think
this is a complete fix. What kind of running threads were using 
invalidated
cache context? These threads may raise plenty of other exceptions if
invalid context is used. I think the proper solution should block a 
guard
(I am sure we already have a guard that we can reuse) and wait for all
threads to release this guard before cleaning up the context.

2015-08-04 8:28 GMT-07:00 Denis Magda <dma...@gridgain.com>:

Hi Alex, Igniters,

I've fixed a deadlock in GridDhtAtomicCache that was a reason of 
frequent
hanging of "Cache Restart" test suite.

In short, the deadlock happened because a cache was already stopped but
some running threads, that perform cache related operations, keep using
invalidated GridCacheContext.
All the details are described here:
https://issues.apache.org/jira/browse/IGNITE-1189 <
https://issues.apache.org/jira/browse/IGNITE-1189>

Alex, as one of earlier implementers of this code, please review the
changes.

Regards,
Denis