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From Modassar Ather <modather1...@gmail.com>
Subject Re: Very high memory and CPU utilization.
Date Mon, 02 Nov 2015 12:47:04 GMT
The problem is with the same query as phrase. q="network se*".

The last . is fullstops for the sentence and the query is q=field:"network
se*"

Best,
Modassar

On Mon, Nov 2, 2015 at 6:10 PM, jim ferenczi <jim.ferenczi@gmail.com> wrote:

> Oups I did not read the thread carrefully.
> *The problem is with the same query as phrase. q="network se*".*
> I was not aware that you could do that with Solr ;). I would say this is
> expected because in such case if the number of expansions for "se*" is big
> then you would have to check the positions for a significant words. I don't
> know if there is a limitation in the number of expansions for a prefix
> query contained into a phrase query but I would look at this parameter
> first (limit the number of expansion per prefix search, let's say the N
> most significant words based on the frequency of the words for instance).
>
> 2015-11-02 13:36 GMT+01:00 jim ferenczi <jim.ferenczi@gmail.com>:
>
> >
> >
> >
> > *I am not able to get  the above point. So when I start Solr with 28g
> RAM,
> > for all the activities related to Solr it should not go beyond 28g. And
> the
> > remaining heap will be used for activities other than Solr. Please help
> me
> > understand.*
> >
> > Well those 28GB of heap are the memory "reserved" for your Solr
> > application, though some parts of the index (not to say all) are
> retrieved
> > via MMap (if you use the default MMapDirectory) which do not use the heap
> > at all. This is a very important part of Lucene/Solr, the heap should be
> > sized in a way that let a significant amount of RAM available for the
> > index. If not then you rely on the speed of your disk, if you have SSDs
> > it's better but reads are still significantly slower with SSDs than with
> > direct RAM access. Another thing to keep in mind is that mmap will always
> > tries to put things in RAM, this is why I suspect that you swap activity
> is
> > killing your performance.
> >
> > 2015-11-02 11:55 GMT+01:00 Modassar Ather <modather1981@gmail.com>:
> >
> >> Thanks Jim for your response.
> >>
> >> The remaining size after you removed the heap usage should be reserved
> for
> >> the index (not only the other system activities).
> >> I am not able to get  the above point. So when I start Solr with 28g
> RAM,
> >> for all the activities related to Solr it should not go beyond 28g. And
> >> the
> >> remaining heap will be used for activities other than Solr. Please help
> me
> >> understand.
> >>
> >> *Also the CPU utilization goes upto 400% in few of the nodes:*
> >> You said that only machine is used so I assumed that 400% cpu is for a
> >> single process (one solr node), right ?
> >> Yes you are right that 400% is for single process.
> >> The disks are SSDs.
> >>
> >> Regards,
> >> Modassar
> >>
> >> On Mon, Nov 2, 2015 at 4:09 PM, jim ferenczi <jim.ferenczi@gmail.com>
> >> wrote:
> >>
> >> > *if it correlates with the bad performance you're seeing. One
> important
> >> > thing to notice is that a significant part of your index needs to be
> in
> >> RAM
> >> > (especially if you're using SSDs) in order to achieve good
> performance.*
> >> >
> >> > Especially if you're not using SSDs, sorry ;)
> >> >
> >> > 2015-11-02 11:38 GMT+01:00 jim ferenczi <jim.ferenczi@gmail.com>:
> >> >
> >> > > 12 shards with 28GB for the heap and 90GB for each index means that
> >> you
> >> > > need at least 336GB for the heap (assuming you're using all of it
> >> which
> >> > may
> >> > > be easily the case considering the way the GC is handling memory)
> and
> >> ~=
> >> > > 1TO for the index. Let's say that you don't need your entire index
> in
> >> > RAM,
> >> > > the problem as I see it is that you don't have enough RAM for your
> >> index
> >> > +
> >> > > heap. Assuming your machine has 370GB of RAM there are only 34GB
> left
> >> for
> >> > > your index, 1TO/34GB means that you can only have 1/30 of your
> entire
> >> > index
> >> > > in RAM. I would advise you to check the swap activity on the machine
> >> and
> >> > > see if it correlates with the bad performance you're seeing. One
> >> > important
> >> > > thing to notice is that a significant part of your index needs to
be
> >> in
> >> > RAM
> >> > > (especially if you're using SSDs) in order to achieve good
> >> performance:
> >> > >
> >> > >
> >> > >
> >> > > *As mentioned above this is a big machine with 370+ gb of RAM and
> Solr
> >> > (12
> >> > > nodes total) is assigned 336 GB. The rest is still a good for other
> >> > system
> >> > > activities.*
> >> > > The remaining size after you removed the heap usage should be
> reserved
> >> > for
> >> > > the index (not only the other system activities).
> >> > >
> >> > >
> >> > > *Also the CPU utilization goes upto 400% in few of the nodes:*
> >> > > You said that only machine is used so I assumed that 400% cpu is
> for a
> >> > > single process (one solr node), right ?
> >> > > This seems impossible if you are sure that only one query is played
> >> at a
> >> > > time and no indexing is performed. Best thing to do is to dump stack
> >> > trace
> >> > > of the solr nodes during the query and to check what the threads are
> >> > doing.
> >> > >
> >> > > Jim
> >> > >
> >> > >
> >> > >
> >> > > 2015-11-02 10:38 GMT+01:00 Modassar Ather <modather1981@gmail.com>:
> >> > >
> >> > >> Just to add one more point that one external Zookeeper instance
is
> >> also
> >> > >> running on this particular machine.
> >> > >>
> >> > >> Regards,
> >> > >> Modassar
> >> > >>
> >> > >> On Mon, Nov 2, 2015 at 2:34 PM, Modassar Ather <
> >> modather1981@gmail.com>
> >> > >> wrote:
> >> > >>
> >> > >> > Hi Toke,
> >> > >> > Thanks for your response. My comments in-line.
> >> > >> >
> >> > >> > That is 12 machines, running a shard each?
> >> > >> > No! This is a single big machine with 12 shards on it.
> >> > >> >
> >> > >> > What is the total amount of physical memory on each machine?
> >> > >> > Around 370 gb on the single machine.
> >> > >> >
> >> > >> > Well, se* probably expands to a great deal of documents,
but a
> huge
> >> > bump
> >> > >> > in memory utilization and 3 minutes+ sounds strange.
> >> > >> >
> >> > >> > - What are your normal query times?
> >> > >> > Few simple queries are returned with in a couple of seconds.
But
> >> the
> >> > >> more
> >> > >> > complex queries with proximity and wild cards have taken
more
> than
> >> 3-4
> >> > >> > minutes and some times some queries have timed out too where
time
> >> out
> >> > is
> >> > >> > set to 5 minutes.
> >> > >> > - How many hits do you get from 'network se*'?
> >> > >> > More than a million records.
> >> > >> > - How many results do you return (the rows-parameter)?
> >> > >> > It is the default one 10. Grouping is enabled on a field.
> >> > >> > - If you issue a query without wildcards, but with approximately
> >> the
> >> > >> > same amount of hits as 'network se*', how long does it take?
> >> > >> > A query resulting in around half a million record return
within a
> >> > couple
> >> > >> > of seconds.
> >> > >> >
> >> > >> > That is strange, yes. Have you checked the logs to see if
> something
> >> > >> > unexpected is going on while you test?
> >> > >> > Have not seen anything particularly. Will try to check again.
> >> > >> >
> >> > >> > If you are using spinning drives and only have 32GB of RAM
in
> >> total in
> >> > >> > each machine, you are probably struggling just to keep things
> >> running.
> >> > >> > As mentioned above this is a big machine with 370+ gb of
RAM and
> >> Solr
> >> > >> (12
> >> > >> > nodes total) is assigned 336 GB. The rest is still a good
for
> other
> >> > >> system
> >> > >> > activities.
> >> > >> >
> >> > >> > Thanks,
> >> > >> > Modassar
> >> > >> >
> >> > >> > On Mon, Nov 2, 2015 at 1:30 PM, Toke Eskildsen <
> >> > te@statsbiblioteket.dk>
> >> > >> > wrote:
> >> > >> >
> >> > >> >> On Mon, 2015-11-02 at 12:00 +0530, Modassar Ather wrote:
> >> > >> >> > I have a setup of 12 shard cluster started with
28gb memory
> each
> >> > on a
> >> > >> >> > single server. There are no replica. The size of
index is
> around
> >> > >> 90gb on
> >> > >> >> > each shard. The Solr version is 5.2.1.
> >> > >> >>
> >> > >> >> That is 12 machines, running a shard each?
> >> > >> >>
> >> > >> >> What is the total amount of physical memory on each machine?
> >> > >> >>
> >> > >> >> > When I query "network se*", the memory utilization
goes upto
> >> 24-26
> >> > gb
> >> > >> >> and
> >> > >> >> > the query takes around 3+ minutes to execute. Also
the CPU
> >> > >> utilization
> >> > >> >> goes
> >> > >> >> > upto 400% in few of the nodes.
> >> > >> >>
> >> > >> >> Well, se* probably expands to a great deal of documents,
but a
> >> huge
> >> > >> bump
> >> > >> >> in memory utilization and 3 minutes+ sounds strange.
> >> > >> >>
> >> > >> >> - What are your normal query times?
> >> > >> >> - How many hits do you get from 'network se*'?
> >> > >> >> - How many results do you return (the rows-parameter)?
> >> > >> >> - If you issue a query without wildcards, but with approximately
> >> the
> >> > >> >> same amount of hits as 'network se*', how long does it
take?
> >> > >> >>
> >> > >> >> > Why the CPU utilization is so high and more than
one core is
> >> used.
> >> > >> >> > As far as I understand querying is single threaded.
> >> > >> >>
> >> > >> >> That is strange, yes. Have you checked the logs to see
if
> >> something
> >> > >> >> unexpected is going on while you test?
> >> > >> >>
> >> > >> >> > How can I disable replication(as it is implicitly
enabled)
> >> > >> permanently
> >> > >> >> as
> >> > >> >> > in our case we are not using it but can see warnings
related
> to
> >> > >> leader
> >> > >> >> > election?
> >> > >> >>
> >> > >> >> If you are using spinning drives and only have 32GB of
RAM in
> >> total
> >> > in
> >> > >> >> each machine, you are probably struggling just to keep
things
> >> > running.
> >> > >> >>
> >> > >> >>
> >> > >> >> - Toke Eskildsen, State and University Library, Denmark
> >> > >> >>
> >> > >> >>
> >> > >> >>
> >> > >> >
> >> > >>
> >> > >
> >> > >
> >> >
> >>
> >
> >
>

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