Package cormoran.pepper.jvm

Interface Summary

Interface	Description
IGCInspector	Interface for GC activity monitoring
IHeapIsTooHigh	Abstract the information defining when we run out of heap.
IPepperGarbageCollectionNotificationInfo	Wraps the not-specified but much useful information in com.sun.management.GarbageCollectionNotificationInfo
IPepperJVMConstants	Typical JVM arguments Class memory parameterization -XX:+UseG1GC -XX:+ExplicitGCInvokesConcurrent -Xmx3G -Xms3G -XX:MaxDirectMemorySize=7G -XX:MaxPermSize=512M java -XX:+PrintFlagsFinal -version > flags.log -XX:+PrintGCApplicationStoppedTime - it prints all STW pauses not only related to GC -XX:+PrintSafepointStatistics - prints safe points details -XX:PrintSafepointStatisticsCount=1 - make JVM report every safe point https://bugs.openjdk.java.net/browse/JDK-6950794 Minimum logs in sysout -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps For -Xloggc, %p.%t are very important else gc logs will be overridden on each restart -Xloggc:../log/jvm_gc.%p.%t.log -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps -XX:+PrintGCDetails -XX:+PrintClassHistogramBeforeFullGC -XX:+PrintClassHistogramAfterFullGC -XX:+PrintGCApplicationStoppedTime -XX:+PrintSafepointStatistics –XX:PrintSafepointStatisticsCount=1 GC rolling -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=10 XX:GCLogFileSize=10M In Prod -XX:-OmitStackTraceInFastThrow will prevent cutting stacks, even if at least the first stack occurrence has been complete http://stackoverflow.com/questions/2411487/nullpointerexception-in-java-with-no-stacktrace # CheckIP with: hostname -i -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=1088 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false -Djava.rmi.server.hostname= Typical monitoring commands jstat -gclog jstack jstack -F Add debug in tomcat: "-Xdebug -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=n" OS Environment variable: JAVA_TOOL_OPTIONS http://www.oracle.com/technetwork/java/javase/tech/vmoptions-jsp-140102.html
IPepperJVMConstants.IPepperActivePivot	-DdefaultChunkSize=131072 -DbufferAllocatorClass=com.qfs.buf.impl.HeapBufferAllocator -DchunkAllocatorClass=com.qfs.chunk.buffer.impl.HeapBufferChunkAllocator -DchunkAllocatorClass=com.qfs.chunk.direct.impl.DirectChunkAllocator -DchunkAllocatorClass=com.qfs.chunk.direct.impl.MmapDirectChunkAllocator -DchunkAllocatorClass=com.qfs.chunk.direct.allocator.impl.SlabMemoryAllocator JGroups does not work with IPv6 -Djava.net.preferIPv4Stack=true
IPepperJVMConstants.IPepperJITAnalysis	JIT Class Compilation audit -XX:+UnlockDiagnosticVMOptions -XX:+LogCompilation -XX:+TraceClassLoading Optionally add -XX:+PrintAssembly https://github.com/AdoptOpenJDK/jitwatch/ https://github.com/AdoptOpenJDK/jitwatch/wiki/Instructions Profiling based on ThreadDumps http://techblog.netflix.com/2015/07/java-in-flames.html
IPepperJVMConstants.IPepperJMCConstants	Enable Java Mission Control http://docs.oracle.com/cd/E15289_01/doc.40/e15070/usingjfr.htm -XX:+UnlockCommercialFeatures -XX:+FlightRecorder One may want additional Stack-traces out of safe points: -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints https://docs.oracle.com/cd/E15289_01/doc.40/e15070/config_rec_data.htm Start from startup.

Class Summary

Class	Description
GCInspector	This class registers itself as listener on GC events.
HeapIsTooHigh	This component enables switching some special mode when the memory is too high: cancel old queries, stop enqueuing in transaction wrapper,...
PepperForOracleJVM	Holds all call to methods/fields not in the Java spec but present in the Oracle jvm
PepperGarbageCollectionNotificationInfo	Wrap the usage of GarbageCollectionNotificationInfo which is restricted API
PepperHeapDumpHelper	Various helpers related to heap-dumps
PepperMathHelper	Helpers related to math and numbers