Vladimir, thank you. Good point for optimistic tx, but still putAll usage require using sorted collections. 
User, of course, may broke this scenario also by using sorted maps with incorrect custom comparators (one asc, one desc).
Producing warning in code for Igntie for potential deadlock is good usability feature.
Please look to user list, deadlock is very often question.

вт, 31 окт. 2017 г. в 21:02, Denis Magda <dmagda@apache.org>:
Vladimir,

That’s an oversight and lack of explanation on our side. The goal is to avoid unexpected deadlocks when a user passed a HashMap in cache.putAll. Before printing out a warning we can filter out OPTIMISTIC/SERIALIZABLE and other suitable scenarios.

So you’re free to offer another solution aside from closing the ticket :) 

Denis

 
On Oct 31, 2017, at 10:55 AM, Vladimir Ozerov <vozerov@gridgain.com> wrote:

Guys,

Printing a warning in this case is really strange idea. First, how would explain it in case of OPTIMISTIC/SERIALIZABLE transactions where deadlocks are impossible? Second, what would you do in case tow sorted maps are passed one by one in a transaction? User still may have a deadlock. :Last, we are going towards SQL world, where "maps" simply do not exist, and virtually any update could eailty lead to a deadlock. 

Let's avoid strange warnings for normal usage scenario. Denis, please close the ticket :-)))

Vladimir.

On Tue, Oct 31, 2017 at 8:34 PM, Denis Magda <dmagda@apache.org> wrote:
Here is a ticket for the improvement:
https://issues.apache.org/jira/browse/IGNITE-6804


Denis

> On Oct 31, 2017, at 3:55 AM, Dmitry Pavlov <dpavlov.spb@gmail.com> wrote:
>
> I agree with Denis, if we don't have such warning we should continiously warn users in wiki pages/blogs/presentations. It is simpler to warn from code.
>
> What do you think if we will issue warning only if size > 1. HashMap with 1 item will not cause deadlock. Moreover where can be some custom singleton Map provided by user.
>
> Sincerely,
> Dmitriy Pavlov
>
> вт, 31 окт. 2017 г. в 7:18, Dmitriy Setrakyan <dsetrakyan@apache.org <mailto:dsetrakyan@apache.org>>:
> Denis,
>
> We should definitely print out a thorough warning if HashMap is passed into
> a bulk method (instead of SortedMap). However, we should make sure that we
> only print that warning once and not ever time the API is called.
>
> Can you please file a ticket for 2.4?
>
> D.
>
> On Thu, Oct 26, 2017 at 11:05 AM, Denis Magda <dmagda@apache.org <mailto:dmagda@apache.org>> wrote:
>
> > + dev list
> >
> > Igniters, that’s a relevant point below. Newcomers to Ignite tend to
> > stumble on deadlocks simply because the keys are passed in an unordered
> > HashMap. Propose to do the following:
> > - update bulk operations Java doc.
> > - print out a warning if a HashMap is used and its exceeds one element.
>
>
> > Thoughts?
> >
> > —
> > Denis
> >
> > > On Oct 21, 2017, at 6:16 PM, dark <ekdxhrl0096@gmail.com <mailto:ekdxhrl0096@gmail.com>> wrote:
> > >
> > > Many people seem to be more likely to send Cache entries in bulk via a
> > > HashMap.
> > > How do you expose a warning statement by checking if the TreeMap is
> > putAll
> > > inside the code?
> > >
> > >
> > >
> > >
> > > --
> > > Sent from: http://apache-ignite-users.70518.x6.nabble.com/ <http://apache-ignite-users.70518.x6.nabble.com/>
> >
> >