SOLR內存不足錯誤讀取索引大型索引時

Question

索引大量數據時，Solr遇到OOM錯誤。我知道一般的建議是將索引拆分成碎片，但事實上情況已經如此。我正在索引分片，並且在這一點上進一步分裂不是一種選擇。我想了解正在發生的事情，爲什麼會出現此錯誤，以及是否有任何事情可以處理，而不是分割或提供更多內存。

如果在這種情況下RAM消耗是線性的（或更糟糕的），我會感到難過，我寧願讓它呈現亞線性。

這種情況是我用隨機字符串索引文件（因此字典非常大）。每份文件都有一對20-30個字符的字段和一個字段大約200-500個字符。每個分片中的索引大小約爲250-260GB，處理該索引的每個solr實例都有大約4GB的內存。當OOM發生時，在重新啓動之後，Solr HeapDump看起來差不多，所以它可能與索引無關，但與Solr搜索器相關。就在OOM前堆轉儲的最大對象如下所示：

<tree type="Heap walker - Biggest objects"> 
    <object leaf="false" class="org.apache.solr.core.SolrCore" objectId="0xf02c" type="instance" retainedBytes="120456864" retainedPercent="97.4"> 
    <outgoing leaf="false" class="org.apache.solr.search.SolrIndexSearcher" objectId="0xfb52" type="instance" retainedBytes="120383232" retainedPercent="97.3" referenceType="not specified" referenceName="[transitive reference]"> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x1018e" type="instance" retainedBytes="8161688" retainedPercent="6.6" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10185" type="instance" retainedBytes="8148072" retainedPercent="6.6" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10188" type="instance" retainedBytes="8138232" retainedPercent="6.6" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10186" type="instance" retainedBytes="8129160" retainedPercent="6.6" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10191" type="instance" retainedBytes="8124608" retainedPercent="6.6" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x1018a" type="instance" retainedBytes="8123144" retainedPercent="6.6" referenceType="not specified" referenceName="[transitive reference]"/> 

     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10192" type="instance" retainedBytes="8100904" retainedPercent="6.5" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10190" type="instance" retainedBytes="8097984" retainedPercent="6.5" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x1018b" type="instance" retainedBytes="8096160" retainedPercent="6.5" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x1018d" type="instance" retainedBytes="8081656" retainedPercent="6.5" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10187" type="instance" retainedBytes="8042504" retainedPercent="6.5" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x1018c" type="instance" retainedBytes="8039336" retainedPercent="6.5" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10189" type="instance" retainedBytes="8036952" retainedPercent="6.5" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x1018f" type="instance" retainedBytes="7948568" retainedPercent="6.4" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10195" type="instance" retainedBytes="832448" retainedPercent="0.7" referenceType="not specified" referenceName="[transitive reference]"/> 

     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10196" type="instance" retainedBytes="830584" retainedPercent="0.7" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10194" type="instance" retainedBytes="829232" retainedPercent="0.7" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10197" type="instance" retainedBytes="828808" retainedPercent="0.7" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10198" type="instance" retainedBytes="827312" retainedPercent="0.7" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10199" type="instance" retainedBytes="824736" retainedPercent="0.7" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x1019a" type="instance" retainedBytes="822608" retainedPercent="0.7" referenceType="not specified" referenceName="[transitive reference]"/> 
     <outgoing leaf="false" class="org.apache.lucene.index.ReadOnlySegmentReader" objectId="0x10193" type="instance" retainedBytes="783424" retainedPercent="0.6" referenceType="not specified" referenceName="[transitive reference]"/> 
     <cutoff objectCount="96" totalSizeBytes="534976" maximumSingleSizeBytes="87560"/> 
    </outgoing> 

    <cutoff objectCount="53" totalSizeBytes="73496" maximumSingleSizeBytes="40992"/> 
    </object> 
    <object leaf="false" class="org.mortbay.jetty.webapp.WebAppClassLoader" objectId="0xdf88" type="instance" retainedBytes="420208" retainedPercent="0.3"/> 
    <object leaf="false" class="org.apache.solr.core.SolrConfig" objectId="0xe5f5" type="instance" retainedBytes="184976" retainedPercent="0.1"/> 
..... 

的JMAP簡單轉儲看起來是這樣的：

Attaching to process ID 27000, please wait... 
Debugger attached successfully. 
Server compiler detected. 
JVM version is 20.5-b03 

using thread-local object allocation. 
Parallel GC with 2 thread(s) 

Heap Configuration: 
    MinHeapFreeRatio = 40 
    MaxHeapFreeRatio = 70 
    MaxHeapSize  = 268435456 (256.0MB) 
    NewSize   = 1310720 (1.25MB) 
    MaxNewSize  = 17592186044415 MB 
    OldSize   = 5439488 (5.1875MB) 
    NewRatio   = 2 
    SurvivorRatio = 8 
    PermSize   = 21757952 (20.75MB) 
    MaxPermSize  = 85983232 (82.0MB) 

Heap Usage: 
PS Young Generation 
Eden Space: 
    capacity = 31719424 (30.25MB) 
    used  = 17420488 (16.61347198486328MB) 
    free  = 14298936 (13.636528015136719MB) 
    54.92056854500258% used 
From Space: 
    capacity = 26673152 (25.4375MB) 
    used  = 10550856 (10.062080383300781MB) 
    free  = 16122296 (15.375419616699219MB) 
    39.55608995892199% used 
To Space: 
    capacity = 27000832 (25.75MB) 
    used  = 0 (0.0MB) 
    free  = 27000832 (25.75MB) 
    0.0% used 
PS Old Generation 
    capacity = 178978816 (170.6875MB) 
    used  = 168585552 (160.7757110595703MB) 
    free  = 10393264 (9.911788940429688MB) 
    94.19302002757689% used 
PS Perm Generation 
    capacity = 42008576 (40.0625MB) 
    used  = 41690016 (39.758697509765625MB) 
    free  = 318560 (0.303802490234375MB) 
    99.24167865152106% used 

我在這裏看不到任何東西，都會給我任何線索，如何處理它，除了提供更多的內存，在一般情況下這不是一個解決方案，我想知道是怎麼回事，爲什麼Searcher和它的ReadOnlySegmentReaders佔用所有內存，他們真的需要，我可以做些什麼嗎？

更新： 我已經做了一個大約150萬字（而不是隨機單詞）的小詞典測試，我達到了大約350GB的索引大小，並沒有OOME，所以這不是直接連接到索引大小，可能必須做更多的術語矢量大小（獨特的條款）。但是我仍然想了解我的侷限性，以及如何繞過它們。

Answer 1

它取決於您獲取您的服務器場的每個「分片」上索引的所有文檔。對於分佈式索引沒有現成的支持，但是您的方法可以像循環技術一樣簡單：將每個文檔索引到圓圈中的下一個服務器。一個簡單的哈希系統也可以工作，Solr Wiki建議uniqueId.hashCode（）％numServers作爲一個適當的哈希函數。

請記住，Solr不計算通用術語/文檔頻率。在大規模情況下，tf/idf在碎片級別計算不太可能是重要的 - 但是，如果您的集合在服務器上的分佈嚴重偏離，則可能會對相關性結果產生影響。它可能是最好的隨機分發文件到你的碎片。 請注意>>>>>>>嘗試使用散列碼代替隨機字符串來索引文檔