I used GC and java only as an example, they are not applicable to Ignite case where we manage offheap memory.
My point is that there is no easy way to implement this feature in Ignite, and more time is needed to properly design it and account for all risks. Thanks, Sergey. On Fri, Aug 4, 2017 at 12:44 PM, <dsetrak...@apache.org> wrote: > Hang on. I thought we were talking about offheap size, GC should not be > relevant. Am I wrong? > > D. > > On Aug 4, 2017, 11:38 AM, at 11:38 AM, Sergey Chugunov < > sergey.chugu...@gmail.com> wrote: > >Do you see an obvious way of implementing it? > > > >In java there is a heap and GC working on it. And for instance, it is > >possible to make a decision to throw an OOM based on some gc metrics. > > > >I may be wrong but I don't see a mechanism in Ignite to use it right > >away > >for such purposes. > >And implementing something without thorough planning brings huge risk > >of > >false positives with nodes stopping when they don't have to. > > > >That's why I think it must be implemented and intensively tested as > >part of > >a separate ticket. > > > >Thanks, > >Sergey. > > > >On Fri, Aug 4, 2017 at 12:18 PM, <dsetrak...@apache.org> wrote: > > > >> Without #3, the #1 and #2 make little sense. > >> > >> Why is #3 so difficult? > >> > >> D. > >> > >> On Aug 4, 2017, 10:46 AM, at 10:46 AM, Sergey Chugunov < > >> sergey.chugu...@gmail.com> wrote: > >> >Dmitriy, > >> > > >> >Last item makes perfect sense to me, one may think of it as an > >> >"OutOfMemoryException" in java. > >> >However, it looks like such feature requires considerable efforts to > >> >properly design and implement it, so I would propose to create a > >> >separate > >> >ticket and agree upon target version for it. > >> > > >> >Items #1 and #2 will be implemented under IGNITE-5717. Makes sense? > >> > > >> >Thanks, > >> >Sergey. > >> > > >> >On Thu, Aug 3, 2017 at 4:34 AM, Dmitriy Setrakyan > >> ><dsetrak...@apache.org> > >> >wrote: > >> > > >> >> Here is what we should do: > >> >> > >> >> 1. Pick an acceptable number. Does not matter if it is 10% or > >50%. > >> >> 2. Print the allocated memory in *BOLD* letters into the log. > >> >> 3. Make sure that Ignite server never hangs due to the low > >memory > >> >issue. > >> >> We should sense it and kick the node out automatically, again > >with > >> >a > >> >> *BOLD* > >> >> message in the log. > >> >> > >> >> Is this possible? > >> >> > >> >> D. > >> >> > >> >> On Wed, Aug 2, 2017 at 6:09 PM, Vladimir Ozerov > >> ><voze...@gridgain.com> > >> >> wrote: > >> >> > >> >> > My proposal is 10% instead of 80%. > >> >> > > >> >> > ср, 2 авг. 2017 г. в 18:54, Denis Magda <dma...@apache.org>: > >> >> > > >> >> > > Vladimir, Dmitriy P., > >> >> > > > >> >> > > Please see inline > >> >> > > > >> >> > > > On Aug 2, 2017, at 7:20 AM, Vladimir Ozerov > >> ><voze...@gridgain.com> > >> >> > > wrote: > >> >> > > > > >> >> > > > Denis, > >> >> > > > > >> >> > > > The reason is that product should not hang user's computer. > >How > >> >else > >> >> > this > >> >> > > > could be explained? I am developer. I start Ignite, 1 node, > >2 > >> >nodes, > >> >> X > >> >> > > > nodes, observe how they join topology. Add one key, 10 keys, > >1M > >> >keys. > >> >> > > Then > >> >> > > > I do a bug in example and load 100M keys accidentally - > >restart > >> >the > >> >> > > > computer. Correct behavior is to have small "maxMemory" by > >> >default to > >> >> > > avoid > >> >> > > > that. User should get exception instead of hang. E.g. Java's > >> >"-Xmx" > >> >> is > >> >> > > > typically 25% of RAM - more adequate value, comparing to > >> >Ignite. > >> >> > > > > >> >> > > > >> >> > > Right, the developer was educated about the Java heap > >parameters > >> >and > >> >> > > limited the overall space preferring OOM to the laptop > >> >suspension. Who > >> >> > > knows how he got to the point that 25% RAM should be used. > >That > >> >might > >> >> > have > >> >> > > been deep knowledge about JVM or he faced several hangs while > >> >testing > >> >> the > >> >> > > application. > >> >> > > > >> >> > > Anyway, JVM creators didn’t decide to predefine the Java heap > >to > >> >a > >> >> static > >> >> > > value to avoid the situations like above. So should not we as > >a > >> >> platform. > >> >> > > Educate people about the Ignite memory behavior like Sun did > >for > >> >the > >> >> Java > >> >> > > heap but do not try to solve the lack of knowledge with the > >> >default > >> >> > static > >> >> > > memory size. > >> >> > > > >> >> > > > >> >> > > > It doesn't matter whether you use persistence or not. > >> >Persistent case > >> >> > > just > >> >> > > > makes this flaw more obvious - you have virtually unlimited > >> >disk, and > >> >> > yet > >> >> > > > you end up with swapping and hang when using Ignite with > >> >default > >> >> > > > configuration. As already explained, the problem is not > >about > >> >> > allocating > >> >> > > > "maxMemory" right away, but about the value of "maxMemory" - > >it > >> >is > >> >> too > >> >> > > big. > >> >> > > > > >> >> > > > >> >> > > How do you know what should be the default then? Why 1 GB? For > >> >> instance, > >> >> > > if I end up having only 1 GB of free memory left and try to > >start > >> >2 > >> >> > server > >> >> > > nodes and an application I will face the laptop suspension > >again. > >> >> > > > >> >> > > — > >> >> > > Denis > >> >> > > > >> >> > > > "We had this behavior before" is never an argument. Previous > >> >offheap > >> >> > > > implementation had a lot of flaws, so let's just forget > >about > >> >it. > >> >> > > > > >> >> > > > On Wed, Aug 2, 2017 at 5:08 PM, Denis Magda > ><dma...@apache.org> > >> >> wrote: > >> >> > > > > >> >> > > >> Sergey, > >> >> > > >> > >> >> > > >> That’s expectable because as we revealed from this > >discussion > >> >the > >> >> > > >> allocation works different depending on whether the > >> >persistence is > >> >> > used > >> >> > > or > >> >> > > >> not: > >> >> > > >> > >> >> > > >> 1) In-memory mode (the persistence is disabled) - the space > >> >will be > >> >> > > >> allocated incrementally until the max threshold is reached. > >> >Good! > >> >> > > >> > >> >> > > >> 2) The persistence mode - the whole space (limited by the > >max > >> >> > threshold) > >> >> > > >> is allocated right away. It’s not surprising that your > >laptop > >> >starts > >> >> > > >> choking. > >> >> > > >> > >> >> > > >> So, in my previous response I tried to explain that I can’t > >> >find any > >> >> > > >> reason why we should adjust 1). Any reasons except for the > >> >massive > >> >> > > >> preloading? > >> >> > > >> > >> >> > > >> As for 2), that was a big surprise to reveal this after 2.1 > >> >release. > >> >> > > >> Definitely we have to fix this somehow. > >> >> > > >> > >> >> > > >> — > >> >> > > >> Denis > >> >> > > >> > >> >> > > >>> On Aug 2, 2017, at 6:59 AM, Sergey Chugunov < > >> >> > sergey.chugu...@gmail.com > >> >> > > > > >> >> > > >> wrote: > >> >> > > >>> > >> >> > > >>> Denis, > >> >> > > >>> > >> >> > > >>> Just a simple example from our own codebase: I tried to > >> >execute > >> >> > > >>> PersistentStoreExample with default settings and two > >server > >> >nodes > >> >> and > >> >> > > >>> client node got frozen even on initial load of data into > >the > >> >grid. > >> >> > > >>> Although with one server node the example finishes pretty > >> >quickly. > >> >> > > >>> > >> >> > > >>> And my laptop isn't the weakest one and has 16 gigs of > >> >memory, but > >> >> it > >> >> > > >>> cannot deal with it. > >> >> > > >>> > >> >> > > >>> > >> >> > > >>> On Wed, Aug 2, 2017 at 4:58 PM, Denis Magda > >> ><dma...@apache.org> > >> >> > wrote: > >> >> > > >>> > >> >> > > >>>>> As far as allocating 80% of available RAM - I was > >against > >> >this > >> >> even > >> >> > > for > >> >> > > >>>>> In-memory mode and still think that this is a wrong > >> >default. > >> >> > Looking > >> >> > > at > >> >> > > >>>>> free RAM is even worse because it gives you undefined > >> >behavior. > >> >> > > >>>> > >> >> > > >>>> Guys, I can not understand how this dynamic memory > >> >allocation's > >> >> > > >> high-level > >> >> > > >>>> behavior (with the persistence DISABLED) is different > >from > >> >the > >> >> > legacy > >> >> > > >>>> off-heap memory we had in 1.x. Both off-heap memories > >> >allocate the > >> >> > > >> space on > >> >> > > >>>> demand, the current just does this more aggressively > >> >requesting > >> >> big > >> >> > > >> chunks. > >> >> > > >>>> > >> >> > > >>>> Next, the legacy one was unlimited by default and the > >user > >> >can > >> >> start > >> >> > > as > >> >> > > >>>> many nodes as he wanted on a laptop and preload as much > >data > >> >as he > >> >> > > >> needed. > >> >> > > >>>> Sure he could bring down the laptop if too many entries > >were > >> >> > injected > >> >> > > >> into > >> >> > > >>>> the local cluster. But that’s about too massive > >preloading > >> >and not > >> >> > > >> caused > >> >> > > >>>> by the ability of the legacy off-heap memory to grow > >> >infinitely. > >> >> The > >> >> > > >> same > >> >> > > >>>> preloading would cause a hang if the Java heap memory > >mode > >> >is > >> >> used. > >> >> > > >>>> > >> >> > > >>>> The upshot is that the massive preloading of data on the > >> >local > >> >> > laptop > >> >> > > >>>> should not fixed with repealing of the dynamic memory > >> >allocation. > >> >> > > >>>> Is there any other reason why we have to use the static > >> >memory > >> >> > > >> allocation > >> >> > > >>>> for the case when the persistence is disabled? I think > >the > >> >case > >> >> with > >> >> > > the > >> >> > > >>>> persistence should be reviewed separately. > >> >> > > >>>> > >> >> > > >>>> — > >> >> > > >>>> Denis > >> >> > > >>>> > >> >> > > >>>>> On Aug 2, 2017, at 12:45 AM, Alexey Goncharuk < > >> >> > > >>>> alexey.goncha...@gmail.com> wrote: > >> >> > > >>>>> > >> >> > > >>>>> Dmitriy, > >> >> > > >>>>> > >> >> > > >>>>> The reason behind this is the need to to be able to > >evict > >> >and > >> >> load > >> >> > > >> pages > >> >> > > >>>> to > >> >> > > >>>>> disk, thus we need to preserve a PageId->Pointer mapping > >in > >> >> memory. > >> >> > > In > >> >> > > >>>>> order to do this in the most efficient way, we need to > >know > >> >in > >> >> > > advance > >> >> > > >>>> all > >> >> > > >>>>> the address ranges we work with. We can add dynamic > >memory > >> >> > extension > >> >> > > >> for > >> >> > > >>>>> persistence-enabled config, but this will add yet > >another > >> >step of > >> >> > > >>>>> indirection when resolving every page address, which > >adds a > >> >> > > noticeable > >> >> > > >>>>> performance penalty. > >> >> > > >>>>> > >> >> > > >>>>> > >> >> > > >>>>> > >> >> > > >>>>> 2017-08-02 10:37 GMT+03:00 Dmitriy Setrakyan < > >> >> > dsetrak...@apache.org > >> >> > > >: > >> >> > > >>>>> > >> >> > > >>>>>> On Wed, Aug 2, 2017 at 9:33 AM, Vladimir Ozerov < > >> >> > > voze...@gridgain.com > >> >> > > >>> > >> >> > > >>>>>> wrote: > >> >> > > >>>>>> > >> >> > > >>>>>>> Dima, > >> >> > > >>>>>>> > >> >> > > >>>>>>> Probably folks who worked closely with storage know > >why. > >> >> > > >>>>>>> > >> >> > > >>>>>> > >> >> > > >>>>>> Without knowing why, how can we make a decision? > >> >> > > >>>>>> > >> >> > > >>>>>> Alexey Goncharuk, was it you who made the decision > >about > >> >not > >> >> using > >> >> > > >>>>>> increments? Do know remember what was the reason? > >> >> > > >>>>>> > >> >> > > >>>>>> > >> >> > > >>>>>>> > >> >> > > >>>>>>> The very problem is that before being started once on > >> >> production > >> >> > > >>>>>>> environment, Ignite will typically be started hundred > >> >times on > >> >> > > >>>>>> developer's > >> >> > > >>>>>>> environment. I think that default should be ~10% of > >total > >> >RAM. > >> >> > > >>>>>>> > >> >> > > >>>>>> > >> >> > > >>>>>> Why not 80% of *free *RAM? > >> >> > > >>>>>> > >> >> > > >>>>>> > >> >> > > >>>>>>> > >> >> > > >>>>>>> On Wed, Aug 2, 2017 at 10:21 AM, Dmitriy Setrakyan < > >> >> > > >>>>>> dsetrak...@apache.org> > >> >> > > >>>>>>> wrote: > >> >> > > >>>>>>> > >> >> > > >>>>>>>> On Wed, Aug 2, 2017 at 7:27 AM, Vladimir Ozerov < > >> >> > > >> voze...@gridgain.com > >> >> > > >>>>> > >> >> > > >>>>>>>> wrote: > >> >> > > >>>>>>>> > >> >> > > >>>>>>>>> Please see original Sergey's message - when > >persistence > >> >is > >> >> > > enabled, > >> >> > > >>>>>>>> memory > >> >> > > >>>>>>>>> is not allocated incrementally, maxSize is used. > >> >> > > >>>>>>>>> > >> >> > > >>>>>>>> > >> >> > > >>>>>>>> Why? > >> >> > > >>>>>>>> > >> >> > > >>>>>>>> > >> >> > > >>>>>>>>> Default settings must allow for normal work on > >> >developer's > >> >> > > >>>>>> environment. > >> >> > > >>>>>>>>> > >> >> > > >>>>>>>> > >> >> > > >>>>>>>> Agree, but why not in increments? > >> >> > > >>>>>>>> > >> >> > > >>>>>>>> > >> >> > > >>>>>>>>> > >> >> > > >>>>>>>>> ср, 2 авг. 2017 г. в 1:10, Denis Magda > >> ><dma...@apache.org>: > >> >> > > >>>>>>>>> > >> >> > > >>>>>>>>>>> Why not allocate in increments automatically? > >> >> > > >>>>>>>>>> > >> >> > > >>>>>>>>>> This is exactly how the allocation works right now. > >> >The > >> >> memory > >> >> > > >> will > >> >> > > >>>>>>>> grow > >> >> > > >>>>>>>>>> incrementally until the max size is reached (80% of > >> >RAM by > >> >> > > >>>>>> default). > >> >> > > >>>>>>>>>> > >> >> > > >>>>>>>>>> — > >> >> > > >>>>>>>>>> Denis > >> >> > > >>>>>>>>>> > >> >> > > >>>>>>>>>>> On Aug 1, 2017, at 3:03 PM, dsetrak...@apache.org > >> >wrote: > >> >> > > >>>>>>>>>>> > >> >> > > >>>>>>>>>>> Vova, 1GB seems a bit too small for me, and > >frankly i > >> >do > >> >> not > >> >> > > want > >> >> > > >>>>>>> t o > >> >> > > >>>>>>>>>> guess. Why not allocate in increments > >automatically? > >> >> > > >>>>>>>>>>> > >> >> > > >>>>>>>>>>> D. > >> >> > > >>>>>>>>>>> > >> >> > > >>>>>>>>>>> On Aug 1, 2017, 11:03 PM, at 11:03 PM, Vladimir > >> >Ozerov < > >> >> > > >>>>>>>>>> voze...@gridgain.com> wrote: > >> >> > > >>>>>>>>>>>> Denis, > >> >> > > >>>>>>>>>>>> No doubts you haven't heard about it - AI 2.1 > >with > >> >> > > persistence, > >> >> > > >>>>>>> when > >> >> > > >>>>>>>>>>>> 80% of > >> >> > > >>>>>>>>>>>> RAM is allocated right away, was released several > >> >days > >> >> ago. > >> >> > > How > >> >> > > >>>>>> do > >> >> > > >>>>>>>> you > >> >> > > >>>>>>>>>>>> think, how many users tried it already? > >> >> > > >>>>>>>>>>>> > >> >> > > >>>>>>>>>>>> Guys, > >> >> > > >>>>>>>>>>>> Do you really think allocating 80% of available > >RAM > >> >is a > >> >> > > normal > >> >> > > >>>>>>>> thing? > >> >> > > >>>>>>>>>>>> Take > >> >> > > >>>>>>>>>>>> your laptop and check how many available RAM you > >> >have > >> >> right > >> >> > > now. > >> >> > > >>>>>>> Do > >> >> > > >>>>>>>>> you > >> >> > > >>>>>>>>>>>> fit > >> >> > > >>>>>>>>>>>> to remaining 20%? If not, then running AI with > >> >persistence > >> >> > > with > >> >> > > >>>>>>> all > >> >> > > >>>>>>>>>>>> defaults will bring your machine down. This is > >> >insane. We > >> >> > > shold > >> >> > > >>>>>>>>>>>> allocate no > >> >> > > >>>>>>>>>>>> more than 1Gb, so that user can play with it > >without > >> >any > >> >> > > >>>>>> problems. > >> >> > > >>>>>>>>>>>> > >> >> > > >>>>>>>>>>>> On Tue, Aug 1, 2017 at 10:26 PM, Denis Magda < > >> >> > > dma...@apache.org > >> >> > > >>>>>>> > >> >> > > >>>>>>>>> wrote: > >> >> > > >>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>> My vote goes for option #1 too. I don’t think > >that > >> >80% is > >> >> > too > >> >> > > >>>>>>>>>>>> aggressive > >> >> > > >>>>>>>>>>>>> to bring it down. > >> >> > > >>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>> IGNITE-5717 was created to fix the issue of the > >80% > >> >RAM > >> >> > > >>>>>>> allocation > >> >> > > >>>>>>>> on > >> >> > > >>>>>>>>>>>> 64 > >> >> > > >>>>>>>>>>>>> bit systems when Ignite works on top of 32 bit > >JVM. > >> >I’ve > >> >> > not > >> >> > > >>>>>>> heard > >> >> > > >>>>>>>> of > >> >> > > >>>>>>>>>>>> any > >> >> > > >>>>>>>>>>>>> other complaints in regards the default > >allocation > >> >size. > >> >> > > >>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>> — > >> >> > > >>>>>>>>>>>>> Denis > >> >> > > >>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>> On Aug 1, 2017, at 10:58 AM, > >dsetrak...@apache.org > >> >> wrote: > >> >> > > >>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>> I prefer option #1. > >> >> > > >>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>> D. > >> >> > > >>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>> On Aug 1, 2017, 11:20 AM, at 11:20 AM, Sergey > >> >Chugunov < > >> >> > > >>>>>>>>>>>>> sergey.chugu...@gmail.com> wrote: > >> >> > > >>>>>>>>>>>>>>> Folks, > >> >> > > >>>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>>> I would like to get back to the question about > >> >> > MemoryPolicy > >> >> > > >>>>>>>>>>>> maxMemory > >> >> > > >>>>>>>>>>>>>>> defaults. > >> >> > > >>>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>>> Although MemoryPolicy may be configured with > >> >initial > >> >> and > >> >> > > >>>>>>>> maxMemory > >> >> > > >>>>>>>>>>>>>>> settings, when persistence is used > >MemoryPolicy > >> >always > >> >> > > >>>>>>> allocates > >> >> > > >>>>>>>>>>>>>>> maxMemory > >> >> > > >>>>>>>>>>>>>>> size for performance reasons. > >> >> > > >>>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>>> As default size of maxMemory is 80% of > >physical > >> >memory > >> >> it > >> >> > > >>>>>>> causes > >> >> > > >>>>>>>>>>>> OOME > >> >> > > >>>>>>>>>>>>>>> exceptions of 32 bit platforms (either on OS > >or > >> >JVM > >> >> > level) > >> >> > > >>>>>> and > >> >> > > >>>>>>>>>>>> hurts > >> >> > > >>>>>>>>>>>>>>> performance in setups when multiple Ignite > >nodes > >> >are > >> >> > > started > >> >> > > >>>>>> on > >> >> > > >>>>>>>>>>>> the > >> >> > > >>>>>>>>>>>>>>> same > >> >> > > >>>>>>>>>>>>>>> physical server. > >> >> > > >>>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>>> I suggest to rethink these defaults and switch > >to > >> >other > >> >> > > >>>>>>> options: > >> >> > > >>>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>>> - Check whether platform is 32 or 64 bits and > >> >adapt > >> >> > > defaults. > >> >> > > >>>>>>> In > >> >> > > >>>>>>>>>>>> this > >> >> > > >>>>>>>>>>>>>>> case we still need to address the issue with > >> >multiple > >> >> > nodes > >> >> > > >>>>>> on > >> >> > > >>>>>>>> one > >> >> > > >>>>>>>>>>>>>>> machine > >> >> > > >>>>>>>>>>>>>>> even on 64 bit systems. > >> >> > > >>>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>>> - Lower defaults for maxMemory and allocate, > >for > >> >> > instance, > >> >> > > >>>>>>>>>>>> max(0.3 * > >> >> > > >>>>>>>>>>>>>>> availableMemory, 1Gb). > >> >> > > >>>>>>>>>>>>>>> This option allows us to solve all issues with > >> >starting > >> >> > on > >> >> > > 32 > >> >> > > >>>>>>> bit > >> >> > > >>>>>>>>>>>>>>> platforms and reduce instability with multiple > >> >nodes on > >> >> > the > >> >> > > >>>>>>> same > >> >> > > >>>>>>>>>>>>>>> machine. > >> >> > > >>>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>>> Thoughts and/or other options? > >> >> > > >>>>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>>>> Thanks, > >> >> > > >>>>>>>>>>>>>>> Sergey. > >> >> > > >>>>>>>>>>>>> > >> >> > > >>>>>>>>>>>>> > >> >> > > >>>>>>>>>> > >> >> > > >>>>>>>>>> > >> >> > > >>>>>>>>> > >> >> > > >>>>>>>> > >> >> > > >>>>>>> > >> >> > > >>>>>> > >> >> > > >>>> > >> >> > > >>>> > >> >> > > >> > >> >> > > >> > >> >> > > > >> >> > > > >> >> > > >> >> > >> >
