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Clustering on Apache/Tomcat using Jakarta mod_jk

Clustering Tomcat Servlet Engines is interesting for two reasons: load balancing and failover.


Fail-over is probably the most important issue for web applications. If the front end load balancer detects that one of the nodes has gone down it will redirect all the traffic to the second instance and your clients, apart from any […]

Networking Properties – Oracle Recommed for Java

Networking Properties

There are a few standard system properties used to alter the mechanisms and behavior of the various classes of the package. Some are checked only once at startup of the VM, and therefore are best set using the -D option of the java command, while others have a more dynamic nature and […]

JAVA using More CPU

In a production environment profiling is not an option, we have seen several times that our CPU has reached almost 100%, we are running tomcat on Linux, so what is happening?

Fortunately, java comes with some great debugging tools, cooperating those tools with Linux built-in tools will let you know what is happening.

Here is what i […]

jvm opts

+AdjustConcurrency +AggressiveOpts +AllowJNIEnvProxy +AllowParallelDefineClass +AllowUserSignalHandlers +AlwaysActAsServerClassMachine +AlwaysCompileLoopMethods +AlwaysLockClassLoader +AlwaysPreTouch +AlwaysRestoreFPU +AlwaysTenure +AnonymousClasses +AssertOnSuspendWaitFailure +BackgroundCompilation +BeParanoid +BindGCTaskThreadsToCPUs +BlockLayoutByFrequency +BlockLayoutRotateLoops +BlockOffsetArrayUseUnallocatedBlock +BranchOnRegister +BytecodeVerificationLocal +BytecodeVerificationRemote +C1OptimizeVirtualCallProfiling +C1ProfileBranches +C1ProfileCalls +C1ProfileCheckcasts +C1ProfileInlinedCalls +C1ProfileVirtualCalls +C1UpdateMethodData +CICompilerCountPerCPU +CITime +CMSAbortSemantics +CMSClassUnloadingEnabled +CMSCleanOnEnter +CMSCompactWhenClearAllSoftRefs +CMSConcurrentMTEnabled +CMSDumpAtPromotionFailure +CMSExtrapolateSweep +CMSIncrementalMode +CMSIncrementalPacing +CMSLoopWarn +CMSOldPLABResizeQuicker +CMSPLABRecordAlways +CMSParallelRemarkEnabled +CMSParallelSurvivorRemarkEnabled +CMSPermGenPrecleaningEnabled +CMSPrecleanRefLists1 +CMSPrecleanRefLists2 +CMSPrecleanSurvivors1 +CMSPrecleanSurvivors2 +CMSPrecleaningEnabled +CMSPrintChunksInDump +CMSPrintObjectsInDump +CMSReplenishIntermediate […]


JVM parameters set whether you know, here and share with you, including JVMHeap regional distribution, JVM’s two GC threads and Stack set and several other parts, I believe that this introduction to your study will be helpful.

Detailed JVM parameter settings

JVMHeap regional distribution:

JavaHeap is divided into three zones, Young, Old and Permanent. Young […]

Java tunning

The general tuning guidelines for java VM. Here are some general tunning guideline to help you categorize the kinds of java tunning you will perform: 1. Be aware of ergonomics settings The -server: server compiler The -XX:+useParallelGC: parallel garbage collector The -Xms: initial heap size is 1/64th of the machine’s physical memory The -Xmx: maximum […]