[ https://issues.apache.org/jira/browse/OAK-808?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
angela resolved OAK-808. ------------------------ Resolution: Later > Significant performance issue in TargetImportHandler's prefix mapping handling > ------------------------------------------------------------------------------ > > Key: OAK-808 > URL: https://issues.apache.org/jira/browse/OAK-808 > Project: Jackrabbit Oak > Issue Type: Bug > Components: jcr > Affects Versions: 0.7 > Reporter: Lukas Eder > Attachments: Screen Shot YourKit Profiling Session.png, > TargetImportHandler.java.patch > > > While playing around with Oak, I have observed a significant performance > bottleneck in > {code} > org.apache.jackrabbit.oak.jcr.xml.TargetImportHandler > {code} > The problem can be seen in the attached Screenshot taken from a Yourkit > profiling session. The TargetImportHandler contains a reference to a > "documentContext" ListMultimap, which acts like a stack of prefix - namespace > mappings. To the outside, however, it is exposed as "documentPrefixMap", a > regular prefix - namespace mapping map, which only references the last > namespace for a prefix. > What's problematic here: "documentPrefixMap" is eagerly copied from > "documentContext" every time the latter is modified, which may happen a lot > in upstream products, such as Adobe CQ5. Instead, "documentPrefixMap" should > be a Map view exposing the desired data. An example implementation using > Guava: > {code} > // Create this view once, in the constructor > this.documentPrefixMap = Maps.transformValues(documentContext.asMap(), > new Function<Collection<String>, String>() { > @Override > public String apply(Collection<String> input) { > return Iterables.getLast(input, null); > } > }); > {code} > The above implementation might work, as "documentPrefixMap" is a read-only > view of the "documentContext" map. More explicit, verbose implementations may > prove to be even faster. > Before I write a patch, please let me know what you think. Having a live view > may of course create concurrency issues, etc. -- This message was sent by Atlassian JIRA (v6.1#6144)