Proffiling

gistfile1.txt

# jstack
 jstack -l <PID> > threads.txt
 
 Generate Heap dump on EOM error
 -XX:+HeapDumpOnOutOfMemoryError
 
 #Heap
 jmap -dump:file=DumpFile.dump <PID>
 jhat DumpFile.dump
 Eclipse MAT -> dominator tree
 
## Display the class name of all ClassLoaders
select classof(cl).name from instanceof java.lang.ClassLoader cl

Query an int array with a length greater than or equal to 256
select a from [I a where a.length >= 256

#async
java -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints -XX:+UseCountedLoopSafepoints -jar <JAR.FILE>
./profiler.sh -d 30 -f /tmp/flamegraph.html <PID>

#Linux process memory
pmap -x <PID>

#Native memoty tracking
java -XX:NativeMemoryTracking=summary -jar <JAR.FILE>
jcmd <PID> VM.native_memory

#Classloader statistic
jcmd <PID> VM.native_memory

#Class statistic
jcmd <PID> GC.class_stats

#LTAB allocation
sudo apt-get install openjdk-8-dbg
./profiler.sh -e alloc -d 10 -f /tmp/flamegraph.html <PID>

#Run application with eadger memory allocation
java -Xms=10G -Xmx=10Gb -XX:+AlwaysPreTouch -jar <JAR.FILE>

#Profile syscalls
profiler.sh -d 10 -e syscall:open <PID>

#Lock
profiler.sh -d 10 -e lock <PID>

#Start JFR
jcmd <PID> JFR.start duration=100s filename=flight.jfr
java -XX:StartFlightRecording=settings=profile.jfc -jar <JAR.FILE>

#Linux show process open files
ls -l /proc/<PID>/fd

#Show process listen sockets
netstat -tulpn | grep <PID>