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WebObjects Optimization
- 1. MONTREAL JUNE 30,JULY 1ST AND 2ND 2012 WebObjects Optimization: EOF and Beyond Chuck Hill,VP Development Global Village Consulting, Inc. Ranked 76th in 24th annual PROFIT 200 ranking of Canada’s Fastest-Growing Companies by PROFIT Magazine! WOWODC 2012
- 2. Session Overview • Outline: • Follow the architecture • Three kinds of optimization: • low effort, high effort, application specific • Most is pretty easy
- 3. A WOrd ofAdvice • Be Productive: Measure, don’t Guess • Seek High ROI (Return On Investment) • Premature Optimization
- 4. Performance Measuring • Use realistic set of data • Beware the first request! • jperf, jmeter, shark, range of options • Simple as NSTimestamp and logging • Wonder has functionality too • WOEvent and EOEvent can be used also
- 5. ERProfiling and HeatMap • From Mike Schrag and Apple • Understand how your app is functioning • Understand why it's slow • Designed around WebObjects • Page-based approach to profiling • Look at the statistics for individual pages and actions
- 6. End to End WO Adaptor Relational Database Client Web Server App Instances
- 7. Browser Considerations • gzip compression • er.extensions.ERXApplication.responseCompressionEnabled=true • Minify js • Combine CSS • Combine images • Minify HTML and CSS
- 8. WebServer Side • mod_gzip • mod_deflate • mod_expires <IfModule mod_expires.c> ExpiresActive On ExpiresDefault A60 ExpiresByType application/javascript A3600 ExpiresByType text/css A3600 ExpiresByType text/html A1
- 9. Apache Tuning • MinSpareServers 10 • KeepAliveTimeout 15 • MaxSpareServers 20 • ServerLimit 2048 • MaxRequestsPerChild 10000 • ListenBackLog 511 • Timeout 45 • MaxClients 128 • MaxKeepAliveRequests 50000
- 10. WO Adaptor Settings • FastCGI in Wonder • Keep worker threads and listen queue size low • Only default (Round Robin) load balancing works(?) • Interleave instances across servers
- 11. Application and Session • setAllowsConcurrentRequestHandling(true); • setCachingEnabled(true); • -WODebuggingEnabled=false • setSessionTimeOut(10 * 60); • setPageCacheSize(5); • setPermanentPageCacheSize(5);
- 12. WOComponents • Stateless components are harder to write but lowers memory usage • Manual binding synchronization requires more code but less processing • Return context().page() instead of null • Lazy creation defers processing and memory usage until needed public String someValue() { if (someValue == null) { // Create someValue here } return someValue; }
- 13. Java • new Integer(8) Integer.valueOf(8) • StringBuffer StringBuilder • Null references when not needed • Heap Size -Xms256m -Xmx512m • Google for advanced heap size tuning articles
- 14. Using the SnapshotCache • Rows for fetches objects stored in EODatabase as snapshots • Snapshots have a Global ID, retain count, and fetch timestamp • Using the row snapshots is fast • following relationships • objectForGlobalID, faultForGlobalID • Consider object freshness needs • Fetch Specs go to database • Raw rows go to database
- 15. EOSharedEditingContext ERXEnterpriseObjectCache • Both address “read mostly” frequent access data • Both prevent snapshots from being discarded • EOSharedEditingContext requires few changes • ... but may introduce bugs. Maybe. • ERXEnterpriseObjectCache requires more work • Key based object access (or global ID) • ... but you have the source and it is commonly used • EOModel “Cache in Memory” never refreshes
- 16. ERXEnterpriseObjectCache Usage ERXEnterpriseObjectCache cache= new ERXEnterpriseObjectCache( entityName, keyPath, restrictingQualifier, timeout, shouldRetainObjects, shouldFetchInitialValues, shouldReturnUnsavedObjects); ERXEnterpriseObjectCache cache = new ERXEnterpriseObjectCache( “BranchOffice”, branchCode, null, 0, true, true, true); public static BranchOffice branchWithCode(EOEditingContext ec, Long id){ return (BranchOffice)officeCache().objectForKey(ec, id); } BranchOffice montrealBranch = BranchOffice.branchWithCode(ec, “MTL”);
- 17. Mass Updates • Sometimes EOF is not the best solution • e.g. bulk deletions will fetch all of the EOs first • ERXEOAccessUtilities • deleteRowsDescribedByQualifier() • updateRowsDescribedByQualifier() • insertRows() • ERXEOAccessUtilities.evaluateSQLWithEntityNamed
- 18. Using Custom SQL • Sometimes there is no other way • Easier than writing a custom EOQualifier • EOUtilities • ERXEOAccessUtilities
- 19. ERXBatchingDisplayGroup • Drop-in replacement for WODisplayGroup • Alternative to limiting data set size • Fetches one batch of EOs at a time • Low memory and fetch overhead • Still fetches all Primary Keys • Kieran’s LIMIT option • ERXBatchNavigationBar • AjaxGrid and AjaxGridNavBar
- 20. Batch Faulting (Fetching) • Optimistically faults in objects • Set in EOModel • Entity or Relationship • How big should a batch be? • Two is twice as good as none • 10 - 20 is a good guess
- 21. Prefetch Relationships • Extension/alternative to batch faulting • Fetches everything at once • Allow for more precise tuning that Batch Faulting • Only useful if you need all / most of the objects • EOFetchSpecification.setPrefetchingRelationshipKeyPaths() • Can only follow class property relationship from root • One fetch per relationship key path with migrated qualifier • Not optimal if most of objects are in snapshot cache
- 22. ERXBatchFetchUtilities • Alternative to pre-fetching and batch faulting • Very focused batching of fetches • Efficiently batch fetch arbitrarily deep key paths • batchFetch(NSArray sourceObjects, NSArray keypaths) • One Gazillion options to control fetch
- 23. When to useRaw Rows • Data ONLY, no logic, no methods, no code, no anything • NSDictionary of key/value pairs • Use with a lot of data from which you only need a few EOs • EOFetchSpecification, EOUtilities, ERXEOAccessUtilities • Late promotion with: • EOUtilities.objectFromRawRow(ec, entityName, row) • ERXEOControlUtilities. faultsForRawRowsFromEntity(ec, rows, entityName)
- 24. EOFetchSpecification Limit • setFetchLimit(int limit) • This may not do what you expect • The standard is to fetch ALL rows and limit in memory • prefetchingRelationshipKeyPaths do not respect LIMIT • Check the SQL! • Wonder fixes SOME databases to LIMIT at database • YOU can fix the rest! Contribute to Wonder! • ERXEOControlUtilities.objectsInRange(ec, spec, start, end, raw)
- 25. Don‘t Model It!Just Say NO! • Avoid unnecessary relationships • Can Model It != Should Model It • Relationships from look-up tables to data • Address TO Country Country TO Address • EOF will fault in ALL of the data rows,VERY slow • Do. Not. Do. This. • Fetch the data IF you ever need it
- 26. Factor out largeCLOBs • Simple and easy to avoid • Fetching large CLOBs (or BLOBs) consumes resources • Move LOB values to their own EO • CLOB EO is to-one and Owns destination • object.clobValue() object.clob().value() • large values are fetched only on demand
- 27. Model Optimization • Trim the fat • Map multiple Entities to same table (read-only, careful!) • Reduce number of attributes locked • De-normalize (views, flattening) • Keep complex data structures in LOBS • Stored Procedures
- 28. Inheritance and Optimization • Inheritance can be very useful • Inheritance can be very slow • Keep hierarchies flat • Avoid concrete super classes • Single Table inheritance is the most efficient • Vertical inheritance is the least efficient
- 29. Monitor the SQL • easiest, cheapest, highest payback performance tuning • -EOAdaptorDebugEnabled true • Watch for: • repeated single row selects • slow queries (more data makes more obvious) • Check for: • indexes for common query terms
- 30. ERXAdaptorChannelDelegate SQLLoggingAdaptorChannelDelegate • Tracks andlogs the SQL that gets sent to the database • ERXAdaptorChannelDelegate • thresholds for logging levels • filter by Entity (regex) • SQLLoggingAdaptorChannelDelegate • CSV formatted log message output for Excel analysis • can log data fetched • can log stack trace of fetch origin
- 31. ERChangeNotificationJMS • Synchronizes EOs and snapshots between application instances • Can reduce fetching • Can reduce need to fetch fresh data • Will reduce save conflicts
- 32. Join Table Indexes • Join tables only get one index • Some EOF generated SQL can’t be optimized • Results in table scan • Manually add complementary index
- 33. Database Tuning • Check the plan, Stan • Cache, cache, cache • RAM, RAM, RAM • Check hit ratio and tune cache size
- 34.
- 35. Counters and Concurrency • Situation: you need to count records according to some criteria • Problems: • counting with a query is too slow • so, create a counters row and update it in real time for new/ updated data • thousands of users creating thousands of events on a short time • huge resource contention for the counter, lots of retries
- 36. Solution • Solution: create several sub-counters! • Counter identifier is one or more columns with whatever you need to identify your counter (FK to other tables, whatever). • SubCounter Number is a number identifying one sub counter for the counter identifier
- 37. How Does itWork? • Define a maximum number of sub counters • When reading, simply select all counters for your identifier, and obtain the sum of the value column. • To update, SubCounter is random number 0 ... max counters - 1 • That’s it.You just reduced the probability of having OL failure and repeating by a factor of 10
- 38. MONTREAL JUNE 30,JULY 1ST AND 2ND 2012 Q&A WebObjects Optimization: EOF and Beyond Chuck Hill Global Village Consulting