Marcel Reutegger created OAK-2621: ------------------------------------- Summary: Too many reads for child nodes Key: OAK-2621 URL: https://issues.apache.org/jira/browse/OAK-2621 Project: Jackrabbit Oak Issue Type: Bug Affects Versions: 1.0 Reporter: Marcel Reutegger Priority: Minor Fix For: 1.1.9
The DocumentNodeStore issues a lot of reads when sibling nodes are deleted, which are also index with a property index. The following calls will become a hotspot: {noformat} at org.apache.jackrabbit.oak.plugins.document.mongo.MongoDocumentStore.query(MongoDocumentStore.java:406) at org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore.readChildDocs(DocumentNodeStore.java:846) at org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore.readChildren(DocumentNodeStore.java:788) at org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore.getChildren(DocumentNodeStore.java:753) at org.apache.jackrabbit.oak.plugins.document.DocumentNodeState.getChildNodeCount(DocumentNodeState.java:194) at org.apache.jackrabbit.oak.plugins.memory.ModifiedNodeState.getChildNodeCount(ModifiedNodeState.java:198) at org.apache.jackrabbit.oak.plugins.memory.MutableNodeState.getChildNodeCount(MutableNodeState.java:265) at org.apache.jackrabbit.oak.plugins.memory.MemoryNodeBuilder.getChildNodeCount(MemoryNodeBuilder.java:293) at org.apache.jackrabbit.oak.plugins.index.property.strategy.ContentMirrorStoreStrategy.prune(ContentMirrorStoreStrategy.java:456) {noformat} I think the code triggering this issue is in {{ModifiedNodeState.getChildNodeCount()}}. It keeps track of already deleted children and requests {{max += deleted}}. The actual {{max}} is always 1 as requested from {{ContentMirrorStoreStrategy.prune()}}, but as more nodes get deleted, the higher {{max}} gets passed to {{DocumentNodeState.getChildNodeCount()}}. The DocumentNodeStore then checks if it has the children in the cache, only to find out the cache entry has too few entries and it needs to fetch one more. It would be best to have a minimum number of child nodes to fetch from MongoDB in this case. E.g. when NodeState.getChildNodeEntries() is called, the DocumentNodeState fetches 100 children. -- This message was sent by Atlassian JIRA (v6.3.4#6332)