ConcMarkSweep probably won't help. Solr 1.4 is not very good at 'near real time' committing. There are some features post-1.4, that I don't know if they are in trunk yet or still just patches, that I have not investigated myself, but google (or JIRA search) for 'near real time'.
http://wiki.apache.org/solr/SolrPerformanceFactors#Updates_and_Commit_Frequency_Tradeoffs This seems to be a very frequent issue these days; everyone running Solr should at least read that wiki section to understand what's going on. ________________________________________ From: John Russell [jjruss...@gmail.com] Sent: Monday, December 13, 2010 8:47 PM To: solr-user@lucene.apache.org Subject: Re: OutOfMemory GC: GC overhead limit exceeded - Why isn't WeakHashMap getting collected? Wow, you read my mind. We are committing very frequently. We are trying to get as close to realtime access to the stuff we put in as possible. Our current commit time is... ahem.... every 4 seconds. Is that insane? I'll try the ConcMarkSweep as well and see if that helps. On Mon, Dec 13, 2010 at 17:38, Jonathan Rochkind <rochk...@jhu.edu> wrote: > Forgive me if I've said this in this thread already, but I'm beginning to > think this is the main 'mysterious' cause of Solr RAM/gc issues. > > Are you committing very frequently? So frequently that you commit faster > than it takes for warming operations on a new Solr index to complete, and > you're getting over-lapping indexes being prepared? > > But if the problem really is just GC issues and not actually too much RAM > being used, try this JVM setting: > > -XX:+UseConcMarkSweepGC > > Will make GC happen in a different thread, instead of the same thread as > solr operations. > > I think that is also something that many many Solr installations probably > need, but don't realize they need. > > > On 12/13/2010 3:42 PM, John Russell wrote: > >> Thanks for the response. >> >> The date types are defined in our schema file like this >> >> <fieldType name="date" class="solr.TrieDateField" omitNorms="true" >> precisionStep="0" positionIncrementGap="0"/> >> >> <!-- A Trie based date field for faster date range queries and date >> faceting. --> >> <fieldType name="tdate" class="solr.TrieDateField" omitNorms="true" >> precisionStep="6" positionIncrementGap="0"/> >> >> Which appears to be what you mentioned. Then we use them in fields like >> this >> >> <field name="sc.publishedDate" type="date" indexed="true" >> stored="false" >> required="false" multiValued="false" /> >> <field name="sc.createdDate" type="date" indexed="true" stored="false" >> required="false" multiValued="false" /> >> >> So I think we have the right datatypes for the dates. Most of the other >> ones are strings. >> >> As for the doc we are adding, I don't think it would be considered "huge". >> It is basically blog posts and tweets broken out into fields like author, >> title, summary etc. Each doc probably isn't more than 1 or 2k tops. Some >> probably smaller. >> >> We do create them once and then update the indexes as we perform work on >> the >> documents. For example, we create the doc for the original incoming post >> and then update that doc with tags or the results of filtering so we can >> look for them later. >> >> We have solr set up as a separate JVM which we talk to over HTTP on the >> same >> box using the solrj client java library. Unfortunately we are on 32 bit >> hardware so solr can only get 2.6GB of memory. Any more than that and the >> JVM won't start. >> >> I really just need a way to keep the cache from breaking the bank. As I >> pasted below there are some config elements in the XML that appear to be >> related to caching but I'm not sure that they are related to that specific >> hashmap which eventually grows to 2.1GB of our 2.6GB heap. It never >> actually runs out of heap space but GC's the CPU to death. >> >> Thanks again. >> >> John >> >> On Sat, Dec 11, 2010 at 17:46, Erick Erickson<erickerick...@gmail.com >> >wrote: >> >> "unfortunately I can't check the statistics page. For some reason the >>> solr >>> webapp itself is only returning a directory listing." >>> >>> This is very weird and makes me wonder if there's something really wonky >>> with your system. I'm assuming when you say "the solr webapp itself" >>> you're >>> taking about ...localhost:8983/solr/admin/...... You might want to be >>> looking >>> at the stats page (and frantically hitting refresh) before you have >>> problems. >>> Alternately, you could record the queries as they are sent to solr to see >>> what >>> the offending >>> >>> But onwards.... Tell us more about your dates. One of the very common >>> ways people get into trouble is to use dates that are unix-style >>> timestamps, >>> i.e. in milliseconds (either as ints or strings) and sort on them. Trie >>> fields >>> are very much preferred for this. >>> >>> Your index isn't all that large by regular standards, so I think that >>> there's >>> hope that you can get this working. >>> >>> >>> Wait, wait, wait. Looking again at the stack trace I see that your OOM >>> is happening when you *add* a document. Tell us more about the >>> document, perhaps you can print out some characteristics of the doc >>> before you add it? Is it always the same doc? Are you indexing and >>> searching on the same machine? Is the doc really huge? >>> >>> Best >>> Erick >>> >>> >>> On Fri, Dec 10, 2010 at 4:33 PM, John Russell<jjruss...@gmail.com> >>> wrote: >>> >>> Thanks a lot for the response. >>>> >>>> Unfortunately I can't check the statistics page. For some reason the >>>> >>> solr >>> >>>> webapp itself is only returning a directory listing. This is sometimes >>>> fixed when I restart but if I do that I'll lose the state I have now. I >>>> can >>>> get at the JMX interface. Can I check my insanity level from there? >>>> >>>> We did change two parts of the solr config to raise the size of the >>>> query >>>> Results and document cache. I assume from what you were saying that >>>> this >>>> does not have an effect on the cache I mentioned taking up all of the >>>> space. >>>> >>>> <queryResultCache >>>> >>>> class=*"solr.LRUCache"* >>>> >>>> size=*"16384"* >>>> >>>> initialSize=*"4096"* >>>> >>>> autowarmCount=*"0"*/> >>>> >>>> >>>> >>>> >>>> >>>> <documentCache >>>> >>>> class=*"solr.LRUCache"* >>>> >>>> size=*"16384"* >>>> >>>> initialSize=*"16384"* >>>> >>>> autowarmCount=*"0"*/> >>>> >>>> >>>> This problem gets worse as our index grows (5.0GB now). Unfortunately >>>> we >>>> are maxed out on memory for our hardware. >>>> >>>> We aren't using faceting at all in our searches right now. We usually >>>> >>> sort >>> >>>> on 1 or 2 fields at the most. I think the types of our fields are >>>> pretty >>>> accurate, unfortunately they are mostly strings, and some dates. >>>> >>>> How do the field definitions effect that cache? Is it simply that fewer >>>> fields mean less to cache? Does it not cache some fields configured in a >>>> certain way? >>>> >>>> Is there a way to throw out an IndexReader after a while and restart, >>>> >>> just >>> >>>> to restart the cache? Or maybe explicitly clear it if we see it getting >>>> >>> out >>> >>>> of hand through JMX or something? >>>> >>>> Really anything to stop it from choking like this would be awesome. >>>> >>>> Thanks again. >>>> >>>> John >>>> >>>> On Fri, Dec 10, 2010 at 16:02, Tom Hill<solr-l...@worldware.com> >>>> wrote: >>>> >>>> Hi John, >>>>> >>>>> WeakReferences allow things to get GC'd, if there are no other >>>>> references to the object referred to. >>>>> >>>>> My understanding is that WeakHashMaps use weak references for the Keys >>>>> in the HashMap. >>>>> >>>>> What this means is that the keys in HashMap can be GC'd, once there >>>>> are no other references to the key. I _think_ this occurs when the >>>>> IndexReader is closed. >>>>> >>>>> It does not mean that objects in the FieldCache will get evicted in >>>>> low memory conditions, unless that field cache entry is no longer >>>>> needed (i.e. the IndexReader has closed). It just means they can be >>>>> collected, when they are no longer needed (but not before). >>>>> >>>>> So, if you are seeing the FieldCache for the current IndexReader >>>>> taking up 2.1, that's probably for the current cache usage. >>>>> >>>>> There isn't a "knob" you can turn to cut the cache size, but you can >>>>> evaluate your usage of the cache. Some ideas: >>>>> >>>>> How many fields are you searching on? Sorting on? Are you sorting on >>>>> String fields, where you could be using a numeric field? Numerics save >>>>> space. Do you need to sort on every field that you are sorting on? >>>>> Could you facet on fewer fields? For a String field, do you have too >>>>> many distinct values? If so, can you reduce the number or unique >>>>> terms? You might check your faceting algorithms, and see if you could >>>>> use enum, instead of fc for some of them. >>>>> >>>>> Check your statistics page, what's your insanity count? >>>>> >>>>> Tom >>>>> >>>>> >>>>> >>>>> On Fri, Dec 10, 2010 at 12:17 PM, John Russell<jjruss...@gmail.com> >>>>> wrote: >>>>> >>>>>> I have been load testing solr 1.4.1 and have been running into OOM >>>>>> >>>>> errors. >>>>> >>>>>> Not out of heap but with the GC overhead limit exceeded message >>>>>> >>>>> meaning >>> >>>> that >>>>> >>>>>> it didn't actually run out of heap space but just spent too much CPU >>>>>> >>>>> time >>>> >>>>> trying to make room and gave up. >>>>>> >>>>>> I got a heap dump and sent it through the Eclipse MAT and found that >>>>>> >>>>> a >>> >>>> single WeakHashMap in FieldCacheImpl called readerCache is taking up >>>>>> >>>>> 2.1GB >>>>> >>>>>> of my 2.6GB heap. >>>>>> >>>>>> From my understanding of WeakHashMaps the GC should be able to >>>>>> >>>>> collect >>> >>>> those >>>>> >>>>>> references if it needs to but for some reason it isn't here. >>>>>> >>>>>> My questions are: >>>>>> >>>>>> 1) Any ideas why the GC is not collecting those weak references in >>>>>> >>>>> that >>> >>>> single hashmap? >>>>>> 2) Is there a nob in the solr config that can limit the size of that >>>>>> >>>>> cache? >>>>> >>>>>> >>>>>> Also, after the OOM is thrown solr doesn't respond much at all and >>>>>> >>>>> throws >>>> >>>>> the exception below, however when I go to the code I see this >>>>>> >>>>>> try { >>>>>> processor.processAdd(addCmd); >>>>>> addCmd.clear(); >>>>>> } catch (IOException e) { >>>>>> throw new >>>>>> SolrException(SolrException.ErrorCode.SERVER_ERROR, "ERROR adding >>>>>> >>>>> document " >>>>> >>>>>> + document); >>>>>> } >>>>>> } >>>>>> >>>>>> So its swallowing the IOException and throwing a new one without >>>>>> >>>>> setting >>>> >>>>> the cause so I can't see what the IOException is. Is this fixed in >>>>>> >>>>> any >>> >>>> newer version? Should I open a bug? >>>>>> >>>>>> >>>>>> Thanks a lot for your help >>>>>> >>>>>> John >>>>>> >>>>>> >>>>>> SEVERE: org.apache.solr.common.SolrException: ERROR adding document >>>>>> SolrInputDocument[{de.id=de.id >>>>>> >>>>> (1.0)={C2B3B03F1000012C549254560A568C18}, >>>> >>>>> de.type=de.type(1.0)={Social >>>>>> Contact}, sc.author=sc.author(1.0)={Author-3944}, >>>>>> sc.sourceType=sc.sourceType(1.0)={rss}, sc.link=sc.link(1.0)={ >>>>>> http://www.cisco.com/feed/date_12.07.10_16.18.03/idx/107 >>>>>> 52}, sc.title=sc.title(1.0)={Title-erat metus eget vestibulum}, >>>>>> sc.publishedDate=sc.publishedDate(1.0)={Tue Dec 07 16:22:09 EST >>>>>> >>>>> 2010}, >>> >>>> sc.createdDate=sc.createdDate(1.0 >>>>>> )={Tue Dec 07 16:20:20 EST 2010}, >>>>>> sc.socialContactStatus=sc.socialContactStatus(1.0)={unread}, >>>>>> sc.socialContactStatusUserId=sc.socialContactStatusUserId(1.0)={}, >>>>>> >>>>> sc.soc >>>> >>>>> ialContactStatusDate=sc.socialContactStatusDate(1.0)={Tue Dec 07 >>>>>> >>>>> 16:20:20 >>>> >>>>> EST 2010}, sc.tags=sc.tags(1.0)={[]}, >>>>>> >>>>> sc.authorId=sc.authorId(1.0)={}, >>> >>>> sc.replyToId=sc.replyTo >>>>>> Id(1.0)={}, sc.replyToAuthor=sc.replyToAuthor(1.0)={}, >>>>>> sc.replyToAuthorId=sc.replyToAuthorId(1.0)={}, >>>>>> sc.feedId=sc.feedId(1.0)={[124852]}, filterResult_124932_ti=filter >>>>>> Result_124932_ti(1.0)={67}, >>>>>> filterStatus_124932_s=filterStatus_124932_s(1.0)={COMPLETED}, >>>>>> filterResult_124937_ti=filterResult_124937_ti(1.0)={67}, >>>>>> filterStatus_124937_s >>>>>> =filterStatus_124937_s(1.0)={COMPLETED}, >>>>>> campaignDateAdded_124957_tdt=campaignDateAdded_124957_tdt(1.0)={Tue >>>>>> >>>>> Dec >>> >>>> 07 >>>>> >>>>>> 16:20:20 EST 2010}, campaignStatus_124957_s=campaign >>>>>> Status_124957_s(1.0)={NEW}, >>>>>> campaignDateAdded_124947_tdt=campaignDateAdded_124947_tdt(1.0)={Tue >>>>>> >>>>> Dec >>> >>>> 07 >>>>> >>>>>> 16:20:20 EST 2010}, campaignStatus_124947_s=campaignStatus_124947 >>>>>> _s(1.0)={NEW}, >>>>>> sc.campaignResultsSummary=sc.campaignResultsSummary(1.0)={[NEW, >>>>>> >>>>> NEW]}}] >>> >>>> at >>>>>> >>>>>> org.apache.solr.handler.BinaryUpdateRequestHandler$2.document(BinaryUpdateRequestHandler.java:81) >>> >>>> at >>>>>> >>>>>> org.apache.solr.client.solrj.request.JavaBinUpdateRequestCodec$2.readOuterMostDocIterator(JavaBinUpdateRequestCodec.java:136) >>> >>>> at >>>>>> >>>>>> org.apache.solr.client.solrj.request.JavaBinUpdateRequestCodec$2.readIterator(JavaBinUpdateRequestCodec.java:126) >>> >>>> at >>>>>> >>>>>> org.apache.solr.common.util.JavaBinCodec.readVal(JavaBinCodec.java:210) >>> >>>> at >>>>>> >>>>>> org.apache.solr.client.solrj.request.JavaBinUpdateRequestCodec$2.readNamedList(JavaBinUpdateRequestCodec.java:112) >>> >>>> at >>>>>> >>>>>> org.apache.solr.common.util.JavaBinCodec.readVal(JavaBinCodec.java:175) >>> >>>> at >>>>>> >>>>>> org.apache.solr.common.util.JavaBinCodec.unmarshal(JavaBinCodec.java:101) >>>> >>>>> at >>>>>> >>>>>> org.apache.solr.client.solrj.request.JavaBinUpdateRequestCodec.unmarshal(JavaBinUpdateRequestCodec.java:141) >>> >>>> at >>>>>> >>>>>> org.apache.solr.handler.BinaryUpdateRequestHandler.parseAndLoadDocs(BinaryUpdateRequestHandler.java:68) >>> >>>> at >>>>>> >>>>>> org.apache.solr.handler.BinaryUpdateRequestHandler.access$000(BinaryUpdateRequestHandler.java:46) >>> >>>> at >>>>>> >>>>>> org.apache.solr.handler.BinaryUpdateRequestHandler$1.load(BinaryUpdateRequestHandler.java:55) >>> >>>> at >>>>>> >>>>>> org.apache.solr.handler.ContentStreamHandlerBase.handleRequestBody(ContentStreamHandlerBase.java:54) >>> >>>> at >>>>>> >>>>>> org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:131) >>> >>>> at org.apache.solr.core.SolrCore.execute(SolrCore.java:1316) >>>>>> at >>>>>> >>>>>> org.apache.solr.servlet.SolrDispatchFilter.execute(SolrDispatchFilter.java:338) >>> >>>> at >>>>>> >>>>>> org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:241) >>> >>>> at >>>>>> >>>>>> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1089) >>> >>>> at >>>>>> >>>>>> org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:365) >>>> >>>>> at >>>>>> >>>>>> org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) >>> >>>> at >>>>>> >>>>>> org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181) >>>> >>>>> at >>>>>> >>>>>> org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:712) >>>> >>>>> at >>>>>> org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405) >>>>>> at >>>>>> >>>>>> org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:211) >>> >>>> at >>>>>> >>>>>> org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114) >>> >>>> at >>>>>> >>>>>> org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139) >>>> >>>>> at org.mortbay.jetty.Server.handle(Server.java:285) >>>>>> at >>>>>> >>>>>> org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:502) >>> >>>> at >>>>>> >>>>>> org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:835) >>> >>>> at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:723) >>>>>> at >>>>>> >>>>> org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:208) >>>>> >>>>>> at >>>>>> >>>>> org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:378) >>>>> >>>>>> at >>>>>> >>>>>> org.mortbay.jetty.bio.SocketConnector$Connection.run(SocketConnector.java:226) >>> >>>> at >>>>>> >>>>>> org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:442) >>> >>
