... Java so fast it blows women's cloths off!

The question I am trying to answer is what does it take to get Java to perform so fast it blows women's cloths off. The goal is not to understand what is fast - but simply to look at techniques which are faster than anything else available.

1. Never use java.util (collections). They generate tremendous amount of garbage and are slow.

• Trove
• Colt
• If you don't believe me - http://b010.blogspot.nl/2009/05/speed-comparison-of-1-javas-built-in.html   

2. Avoid garbage collection

• http://docs.oracle.com/cd/E19900-01/819-4742/abeik/index.html - No minor GC collections until Eden fills up - so make your Eden larger. (-XX:MaxNewSize)
• http://java-performance.info/overview-of-memory-saving-techniques-java/

 3. Reuse strings.

• http://java-performance.info/string-intern-in-java-6-7-8/
• https://github.com/OpenHFT/Java-Lang/blob/master/lang/src/main/java/net/openhft/lang/pool/StringInterner.java - very quick way to do on heap intern

3. Async Logging - i.e. don't spend all your time writing logs

• http://logging.apache.org/log4j/2.x/manual/async.html
• https://github.com/OpenHFT/Java-Chronicle - record everything for high-frequency-trading (read fast enough to blow women's cloths off)

4. Don't use the Heap - i.e. No heap = no GC.

• https://github.com/OpenHFT/HugeCollections - off heap storage
• https://github.com/OpenHFT/Java-Lang

5.  Know what the heck your system is doing. Maybe it's the machine and not your crappy-code?

• http://www.azulsystems.com/jhiccup - unexplained processing pauses
• http://dtrace.org/blogs/brendan/2013/06/08/linux-performance-analysis-and-tools/ - tools to monitor Linux
• http://www.joyent.com/blog/the-new-systems-performance - some more tools

6. Use a ring instead of a queue / thread message passing

• http://lmax-exchange.github.io/disruptor/ - inter thread message passing.

7. Maybe the problem isn't with your code at all - but with the watch you use?

• https://github.com/hajile/microclock - library implementing RDTSC (let's count the CPU clock cycles)
• http://www.strchr.com/performance_measurements_with_rdtsc
• https://github.com/giltene/HdrHistogram - more precise measurements

8. Keep your methods short and sweet - helps with hotspot

•  Write code that is easy for the optimizer - https://wikis.oracle.com/display/HotSpotInternals/PerformanceTechniques

9. Try some exotic features

• https://github.com/OpenHFT/Java-Thread-Affinity - Thread affinity
• http://www.docjar.com/docs/api/sun/misc/Unsafe.html - a magical class in the JDK, which does everything a magnitude faster, but don't use it without protection. It's unsafe. 
• http://architects.dzone.com/articles/getting-cc-performance-java - serialization using Unsafe

 10. CAS / optimistic locking / lock free

• http://java.dzone.com/articles/lock-based-vs-lock-free - no locks is a lot faster than with locks (no shit).
• http://www.infoq.com/articles/memory_barriers_jvm_concurrency - use volatile but only at your own risk
• 
  

DemiGods in this space - 

• http://mechanical-sympathy.blogspot.com/ - LMAX Tech Architect Guy
• http://vanillajava.blogspot.com/ - HFT Java Guy

JVM Monitoring List

Yes - it's another list. In the last few days, I've had a perverse desire to make lists. This one is for tools that allow for JVM monitoring both internal or external.


Tools:

• http://visualvm.java.net/ - Visual VM
• http://docs.oracle.com/javase/7/docs/technotes/guides/management/jconsole.html - JConsole
• http://www.oracle.com/technetwork/java/javaseproducts/mission-control  - Mission Control 
• http://docs.oracle.com/javase/7/docs/technotes/tools/share/jstat.html
• http://docs.oracle.com/javase/6/docs/technotes/tools/share/jmap.html

Open Source:

• http://code.google.com/p/javasimon/

Vendors:

• http://www.appdynamics.com/
• http://chrononsystems.com/
• http://newrelic.com/java 
• http://www.yourkit.com/ 
• https://profiler.netbeans.org/ 
• http://www.ej-technologies.com/products/jprofiler/overview.html
• http://www.correlsense.com
• http://www.quest.com/foglight-for-java/
• http://www.manageengine.com/products/applications_manager/monitor-jvm-performance.html

• http://www.compuware.com/en_us/application-performance-management/products/purepath-technology.html (DynaTrace)

Metrics:

• https://github.com/Netflix/servo/
• https://github.com/etsy/statsd
• https://github.com/etsy/skyline

Log Aggregation

• http://www.elasticsearch.org/overview/kibana/
• http://www.elasticsearch.org/
• http://logstash.net/
• http://www.splunk.com
• http://sematext.com/logsene/index.html

Tutorials:

• http://www.joyent.com/blog/the-new-systems-performance
• http://dtrace.org/blogs/brendan/2013/06/08/linux-performance-analysis-and-tools/
• http://dtrace.org/blogs/brendan/2012/03/07/the-use-method-linux-performance-checklist/
• http://codeascraft.com/2011/02/15/measure-anything-measure-everything/

Distributed File System List

I feel like making lists. I guess it's a human condition to make lists and organize things. So to satisfy my desire below is a list of distributed file system providers:

Providers:

• http://hadoop.apache.org/docs/stable/hdfs_design.html  - HDFS
• http://fuse.sourceforge.net/  - FUSE
• http://www.xtreemfs.org/  
• http://ceph.com/
• http://www.coda.cs.cmu.edu/
• http://code.google.com/p/kosmosfs/
• https://github.com/quantcast/qfs

 Tutorials:

• http://www.cs.nmsu.edu/~pfeiffer/fuse-tutorial/
• http://www.ibm.com/developerworks/library/l-fuse/
• http://www.ibm.com/developerworks/library/wa-introhdfs/

LP Solvers List

I am feeling like making lists. I guess it's the human condition to want to organize and categorize. For this post, I will focus on linear programming solver libraries and links:


Open Source:

• http://www.gnu.org/software/glpk/
• http://sourceforge.net/projects/lpsolve/
• http://commons.apache.org/proper/commons-math/userguide/linear.html
• http://ojalgo.org/
• http://www.coin-or.org/projects/Clp.xml
• http://www.joptimizer.com/
• http://jscience.org/
• http://mikiobraun.github.io/jblas/

 Commercial:

• http://www-01.ibm.com/software/commerce/optimization/cplex-optimizer/
• http://msdn.microsoft.com/en-us/devlabs/hh145003.aspx - Microsoft Solver Foundation
• http://reference.wolfram.com/mathematica/tutorial/ConstrainedOptimizationLinearProgramming.html - Wolfram Mathematica
• http://www.gurobi.com/
• http://www.lindo.com/
• http://www.fico.com/en/Products/DMTools/Pages/FICO-Xpress-Optimization-Suite.aspx
• http://www.mosek.com/ 
• http://www.solver.com/ - Excel Solver
• http://www.ziena.com/
• http://www.ampl.com/
• http://numericalmethod.com/suanshu/
• http://www.ateji.com/optimj/index.html

GC Parameters List

I am always on the lookout for common GC parameters. So I figured I'll compile a list of some of the common parameters and places where I found them:

Super Lists of All Parameters:

1. http://www.oracle.com/technetwork/java/javase/tech/vmoptions-jsp-140102.html 
2. http://stas-blogspot.blogspot.fi/2011/07/most-complete-list-of-xx-options-for.html
3. http://blog.ragozin.info/2011/09/hotspot-jvm-garbage-collection-options.html
4. http://reins.altervista.org/java/A_Collection_of_JVM_Options_MP.html 

Blog Roll

• http://practicingtechie.wordpress.com/2013/06/15/java-vm-options/
  
  • -XX:+UseConcMarkSweepGC
  • -XX:+HeapDumpOnOutOfMemoryError
  • -XX:HeapDumpPath=$APP_HOME_DIR
  • -XX:OnOutOfMemoryError=
  • -XX:OnError=
  • -XX:+PrintGCDetails
  • -XX:+PrintGCTimeStamps
  • -Xloggc:$APP_HOME_DIR/gc.log
  • -XX:-UseGCLogFileRotation
  • -XX:GCLogFileSize=M 
  • -XX:NumberOfGCLogFiles=

• http://community.gemstone.com/display/gemfire60/GC+Tuning
  
  • -XX:NewSize=m 
  • -XX:CMSInitiatingOccupancyFraction=N
  • -XX:+UseConcMarkSweepGC
  • -Xmxm
  • -Xmsm

• http://blog.mikiobraun.de/2010/08/cassandra-gc-tuning.html  
  
  • -XX:+UseConcMarkSweepGC 
  • -XX:ParallelCMSThreads=1  
  • -XX:+CMSIncrementalMode  
  • -XX:+CMSIncrementalPacing  
  • -XX:CMSIncrementalDutyCycleMin=0  
  • -XX:CMSIncrementalDutyCycle=10 

• https://blogs.atlassian.com/2013/02/a-little-practical-gc-tuning-on-eclipse/ 
• -server
• -XX:MaxPermSize=320m
• -XX:+UseParallelGC
• -Xmx3g
• -Xmn2g
• -XX:+DisableExplicitGC

• http://themindstorms.wordpress.com/2009/01/21/advanced-jvm-tuning-for-low-pause/ 
• -Xms2g
• -Xmx2g
• -Xmn150m 
• -XX:GCTimeRatio=2 
• -XX:ParallelGCThreads=8 
• -XX:+UseParNewGC 
• -XX:MaxGCPauseMillis=2000 
• -XX:+DisableExplicitGC

• http://forum.openspaces.org/thread.jspa?messageID=9277 
• -Xms2g 
• -Xmx2g 
• -XX:+UseConcMarkSweepGC 
• -XX:+CMSIncrementalMode 
• -XX:+CMSIncrementalPacing 
• -XX:CMSIncrementalDutyCycleMin=10 
• -XX:CMSIncrementalDutyCycle=50 
• -XX:ParallelGCThreads=8 
• -XX:+UseParNewGC 
• -Xmn150m 
• -XX:MaxGCPauseMillis=2000 
• -XX:GCTimeRatio=10 
• -XX:+DisableExplicitGC 

• http://java-is-the-new-c.blogspot.com/
• -Xms11g 
• -Xmx11g 
• -verbose:gc 
• -XX:-UseAdaptiveSizePolicy 
• -XX:SurvivorRatio=12 
• -XX:NewSize=100m 
• -XX:MaxNewSize=100m 
• -XX:MaxTenuringThreshold=2

• http://techblog.netflix.com/2013/05/garbage-collection-visualization.html
• -verbose:gc
• -verbose:sizes
• -Xloggc:/apps/tomcat/logs/gc.log
• -XX:+PrintGCDetails
• -XX:+PrintGCDateStamps
• -XX:+PrintTenuringDistribution
• -XX:-UseGCOverheadLimit
• -XX:+ExplicitGCInvokesConcurrent
• -XX:+UseConcMarkSweepGC
• -XX:+CMSScavengeBeforeRemark
• -XX:+CMSParallelRemarkEnabled

• https://access.redhat.com/site/documentation/en-US/JBoss_Enterprise_Application_Platform/5/html/Performance_Tuning_Guide/sect-Performance_Tuning_Guide-Java_Virtual_Machine_Tuning-Garbage_Collection_and_Performance_Tuning.html
• -Xms12288m
• -Xmx12288m
• -XX:+UseLargePages
• -XX:+UseParallelOldGC

• http://onthejvm.blogspot.com/2013/05/java-gc-tuning-for-high-frequency.html
• -XX:+UnlockDiagnosticVMOptions 
• -Xmx4g 
• -Xms4g 
• -XX:MaxNewSize=3g 
• -XX:NewSize=3g 
• -XX:ParallelGCThreads=7 
• -XX:+UseGCTaskAffinity 
• -XX:+BindGCTaskThreadsToCPUs 
• -XX:ParGCCardsPerStrideChunk=32768
  

• http://glipho.com/albert/performance-effects-of-garbage-collection-tuning-on-java
• -XX:+UseConcMarkSweepGC
• -XX:ParallelCMSThreads=8
• -XX:+CMSIncrementalMode
• -XX:+CMSIncrementalPacing
• -XX:CMSIncrementalDutyCycleMin=0
• -XX:CMSIncrementalDutyCycle=10

• http://docs.neo4j.org/chunked/milestone/configuration-jvm.html
• -Xmx
• -XX:+UseConcMarkSweepGC
• -XX:NewRatio=#

• http://blog.igorminar.com/2010/07/dgc-ii-jvm-tuning.html 
• -XX:+UseConcMarkSweepGC
• -XX:+UseParNewGC
• -XX:CMSInitiatingOccupancyFraction=68
• -XX:MaxTenuringThreshold=31
• -XX:+CMSParallelRemarkEnabled
• -XX:SurvivorRatio=6
• -XX:TargetSurvivorRatio=90 
• -XX:+AggressiveOpts
• -XX:+DoEscapeAnalysis 
• -Xloggc:/some/path/
• -XX:+PrintGCDetails 
• -XX:+PrintGCTimeStamps
• -XX:+PrintGCDateStamps
• -XX:+PrintTenuringDistribution
• -XX:+HeapDumpOnOutOfMemoryError
• -Xmn2818m 

• http://blog.performize-it.com/2013/09/jvm-params-everyone-should-have-in.html
• -Xms{#MB}m -Xmx{#MB}m
• -XX:PermSize={#MB}m -XX:MaxPermSize={#MB}m
• -XX:+HeapDumpOnOutOfMemoryError
• -XX:+PrintFlagsFinal
• -server
• -XX:+PrintGCDetails
• -XX:+PrintGCDateStamps 
• -XX:+PrintTenuringDistribution 
• -XX:+PrintGCApplicationStoppedTime 
• -XX:+PrintGCApplicationConcurrentTime  
• -XX:+UseGCLogFileRotation
• -XX:NumberOfGCLogFiles={#files}
• -XX:GCLogFileSize={#MB}M
• -Xloggc:{some gc log file}.gc 
• -Dcom.sun.management.jmxremote
• -Dcom.sun.management.jmxremote.port={a port}
• -Dcom.sun.management.jmxremote.authenticate=false
• -Dcom.sun.management.jmxremote.authenticate=false

• Big Bank System with a very large Heap (~80gb)
• -d64
• -server
• -XX:+AggressiveOpts
• -XX:+UseConcMarkSweepGC
• -XX:+UseParNewGC
• -XX:ParallelGCThreads=4
• -XX:NewRatio=4

 Tools

1. https://github.com/foursquare/heapaudit
2. https://github.com/twitter/jvmgcprof
3. https://github.com/Netflix/gcviz
4. https://github.com/chewiebug/GCViewer

Tutorials

1. http://www.slideshare.net/aszegedi/everything-i-ever-learned-about-jvm-performance-tuning-twitter
2. http://java.dzone.com/articles/how-tame-java-gc-pauses
3. http://blog.ragozin.info/p/garbage-collection.html
4. http://blog.ragozin.info/2011/10/techtalk-garbage-collection-in-java.html
5. https://blogs.oracle.com/jonthecollector/entry/the_second_most_important_gc
6. http://stackoverflow.com/questions/17009961/understanding-the-java-memory-model-and-garbage-collection
7. http://mechanical-sympathy.blogspot.com/2013/07/java-garbage-collection-distilled.html
8. http://blog.mgm-tp.com/2013/03/garbage-collection-tuning/
9. http://www.youtube.com/watch?v=o6qx_zvpOyI  
10. http://www.infoq.com/presentations/Virtualizing-Tuning-JVM
11. https://blog.codecentric.de/en/2013/10/useful-jvm-flags-part-7-cms-collector/
12. http://blog.headius.com/2009/01/my-favorite-hotspot-jvm-flags.html 
13. http://www.oracle.com/technetwork/java/javase/gc-tuning-6-140523.html
14. http://java.dzone.com/articles/java-garbage-collection-0