Hi Maulin, To clarify, when you said "...allocated 40 GB RAM to each shard." above, I'm going to assume you meant "to each node" instead. If you actually did mean "to each shard" above, please correct me and anyone who chimes in afterward.
Firstly, it's really hard to even take guesses about potential causes or remediations without more details about your load characteristics (average/peak QPS, index size, average document size, etc.). If no one gives any satisfactory advice, please consider uploading additional details to help us help you. Secondly, I don't know anything about the load characteristics you're putting on your Solr cluster, but I'm curious whether you've experimented with lower RAM settings. Generally speaking, the more RAM you have, the longer your GC pauses are likely to be (even with the tuning that various GC settings provide). If you can get away with giving the Solr process less RAM, you should see your GC pauses shrink. Was 40GB chosen after some trial-and-error experimentation, or is it something you could investigate? For a bit more overview on this, see this slightly outdated (but still useful) wiki page: https://wiki.apache.org/solr/SolrPerformanceProblems#RAM Hope that helps, even if just to disqualify some potential causes/solutions to close in on a real fix. Best, Jason On Wed, Jan 31, 2018 at 8:17 AM, Maulin Rathod <mrat...@asite.com> wrote: > Hi, > > We are using solr cloud 6.1. We have around 20 collection on 4 nodes (We > have 2 shards and each shard have 2 replicas). We have allocated 40 GB RAM > to each shard. > > Intermittently we found long GC pauses (60 sec to 200 sec) due to which > solr stops responding and hence collections goes in recovering mode. It > takes minimum 5-10 minutes (sometime it takes more and we have to restart > the solr node) for recovering all collections. We are using default GC > setting (CMS) as per solr.cmd. > > We tried different G1 GC to see if it help, but still we see long GC > pauses(60 sec to 200 sec) and also found that memory usage is more in in > case G1 GC. > > What could be reason for long GC pauses and how can fix it? Insufficient > memory or problem with GC setting or something else? Any suggestion would > be greatly appreciated. > > In our analysis, we also found some inefficient queries (which uses * many > times in query) in solr logs. Could it be reason for high memory usage? > > Slow Query > -------------- > > INFO (qtp1239731077-498778) [c:documents s:shard1 r:core_node1 > x:documents] o.a.s.c.S.Request [documents] webapp=/solr path=/select > params={df=summary&distrib=false&fl=id&shards.purpose=4& > start=0&fsv=true&sort=description+asc,id+desc&fq=&shard.url= > s1.asite.com:8983/solr/documents|s1r1.asite.com: > 8983/solr/documents&rows=250&version=2&q=((id:( > REV78364_24705418+REV78364_24471492+REV78364_24471429+ > REV78364_24470771+REV78364_24470271+))+OR+summary:((HPC*+ > AND+*+AND+*+AND+OH1150*+AND+*+AND+*+AND+U0*+AND+*+AND+*+AND+ > HGS*+AND+*+AND+*+AND+MDL*+AND+*+AND+*+AND+100067*+AND+*+AND+ > -*+AND+Reinforcement*+AND+*+AND+Mode*)+))++AND++(title:((* > HPC\+\-\+OH1150\+\-\+U0\+\-\+HGS\+\-\+MDL\+\-\+100067\+-\+ > Reinforcement\+Mode*)+))+AND+project_id:(-2+78243+78365+ > 78364)+AND+is_active:true+AND+((isLatest:(true)+AND+ > isFolderActive:true+AND+isXref:false+AND+-document_ > type_id:(3+7)+AND+((is_public:true+OR+distribution_list: > 4858120+OR+folderadmin_list:4858120+OR+author_user_id: > 4858120)+AND+((defaultAccess:(true)+OR+allowedUsers:( > 4858120)+OR+allowedRoles:(6342201+172408+6336860)+OR+ > combinationUsers:(4858120))+AND+-blockedUsers:(4858120)))) > +OR+(isLatestRevPrivate:(true)+AND+allowedUsersForPvtRev:( > 4858120)+AND+-folderadmin_list:(4858120)))&shards.tolerant=true&NOW= > 1516786982952&isShard=true&wt=javabin} hits=0 status=0 QTime=83309 > > > > > Regards, > > Maulin > > [CC Award Winners!] > >
