Suresh's Tech Notes 1.0 Help

JVM Profiling

1. Flight Recorder

2. Java Mission Control

# https://jdk.java.net/jmc/ # https://adoptium.net/jmc # https://github.com/adoptium/jmc-build/releases # https://github.com/corretto/corretto-jmc/releases # https://www.oracle.com/java/technologies/jdk-mission-control.html # https://www.azul.com/products/components/zulu-mission-control/ $ curl https://github.com/adoptium/jmc-build/releases/download/8.2.0/org.openjdk.jmc-8.2.0-macosx.cocoa.x86_64.tar.gz | tar xv - $ rm -rf "/Applications/JDK Mission Control.app" $ mv "JDK Mission Control.app" /Applications $ open '/Applications/JDK Mission Control.app' # To run with a JDK $ ./jmc -vm %JAVA_HOME%\bin # or $ open '/Applications/JDK Mission Control.app' --args -vm $JAVA_HOME/bin

3. Visualization

FlameGraph of java threads

$ wget https://github.com/brendangregg/FlameGraph/raw/master/flamegraph.pl $ wget https://github.com/brendangregg/FlameGraph/raw/master/stackcollapse-jstack.pl $ chmod +x *.pl # Run multiple times to get more samples $ jcmd GradleDaemon Thread.print >> jcmd.tdump $ stackcollapse-jstack.pl jcmd.tdump > jcmd.tdump.folded $ flamegraph.pl --color=io --title "Thread Dump" --countname "Samples" --width 1080 jcmd.tdump.folded > jcmd.tdump.svg

JFR to FlameGraph

# Download the latest release from Github $ LOCATION=$(curl -sL https://api.github.com/repos/jvm-profiling-tools/async-profiler/releases/latest \ | grep -i "browser_download_url" \ | grep -i "converter.jar" \ | awk '{ print $2 }' \ | sed 's/,$//' \ | sed 's/"//g' ) \ ; curl --progress-bar -L -o ${HOME}/install/tools/converter.jar ${LOCATION} $ java -cp ${HOME}/install/tools/converter.jar \ jfr2flame --total --dot --lines \ openjdk-playground.jfr flame.html $ open flame.html

CPU/Memory Viz of a process

Script

# Download the script $ wget https://github.com/sureshg/openjdk-playground/raw/main/scripts/cpu-mem-viz.sh # Record CPU/Memory usage of a process $ ./scripts/cpu-mem-viz.sh --pid <pid> # Generate visualization using gunplot $ ./scripts/cpu-mem-viz.sh --pid <pid> -a gnuplot $ open -a "Google Chrome" gnuplot-<pid>.svg # Generate visualization using vega-lite $ sudo npm install -g vega-lite vega-cli $ ./scripts/cpu-mem-viz.sh --pid <pid> -a vega $ open -a "Google Chrome" vega-lite-<pid>.svg

Misc Tools

# Using htop $ htop -p $(pgrep -f idea) # Using psrecord $ pip install matplotlib psrecord $ psrecord $(pgrep -f idea) --plot plot.png --log activity.txt --include-children --duration 5 $ open plot.png

4. Profilers & Tools

5. Commands

  • Wizard to create configuration files (.jfc)

    $ jfr configure --interactive $ jfr summary openjdk-playground.jfr # Concat multiple JFR files $ jfr assemble <repository> <file> // cat jfr_file_version_* >> combined.jfr # Print specific event details $ jfr print --events 'jdk.*' --stack-depth 64 openjdk-playground.jfr $ jfr print --events CPULoad,GarbageCollection openjdk-playground.jfr # Pinned virtual threads $ jfr print --events jdk.VirtualThreadPinned openjdk-playground.jfr # Remove passwords from JFR $ jfr scrub --exclude-events InitialEnvironmentVariable recording.jfr no-psw.jfr # Search for JFR metadata $ jfr metadata | grep -i -e "tls" -e "x509" -e "security" | grep -i "@Name"

    Some config options are,

    -XX:StartFlightRecording:filename=recording.jfr -XX:FlightRecorderOptions:stackdepth=256 -XX:+HeapDumpOnOutOfMemoryError -XX:ErrorFile=$USER_HOME/java_error_in_app_%p.log -XX:HeapDumpPath=$USER_HOME/java_error_in_app.hprof

6.JFR Streaming

7. HeapDump

Analyze using JOL

$ curl -sL https://builds.shipilev.net/jol/jol-cli-latest.jar > jol-cli.jar $ java -jar jol-cli.jar heapdump-stats heapdump.hprof

8. ThreadDump

# Get all java processes $ jcmd -l $ jps -mlvV # See the available commands for all java processes $ jcmd 0 help # Use PID or main class $ jcmd dev.suresh.Main VM.version $ jcmd <dev.suresh.Main | pid> Thread.print # Virtual thread dump $ jcmd dev.suresh.Main Thread.dump_to_file -format=json openjdk-playground-threads.json # OR $ kill -3 <pid> $ kill -3 "$(jcmd -l | grep "dev.suresh.Main" | cut -d " " -f1)" # OR # Prints additional info about thread (-e extended listing) and locks (-l long listing) $ jstack -l -e <pid> # Show Native Memory $ jcmd GradleDaemon VM.native_memory

9. Load Testing

# Run Gataling Recorder and select listening port as 9999 $ ~/install/gatling/bin/recorder.sh $ Confiure it as system proxy GATALING_PROXY_PORT=9999 NETWORK_SERVICE="Wi-Fi" networksetup -getwebproxy $NETWORK_SERVICE networksetup -getsecurewebproxy $NETWORK_SERVICE networksetup -setwebproxy $NETWORK_SERVICE localhost $GATALING_PROXY_PORT networksetup -setsecurewebproxy $NETWORK_SERVICE localhost $GATALING_PROXY_PORT # Browse the application URLs, Stop recording & Switch off the proxy networksetup -setwebproxystate $NETWORK_SERVICE off networksetup -setsecurewebproxystate $NETWORK_SERVICE off # Run simulation $ ~/install/gatling/bin/gatling.sh --run-mode local --simulation dev.suresh.LoadTest

10. Unified GC Logging

$ java -Xlog:help # For G1GC $ java -XX:+UseG1GC -XX:MaxGCPauseMillis=200 -XX:InitiatingHeapOccupancyPercent=70 -XX:+PrintGC -XX:+PrintGCDateStamps -XX:+PrintGCDetails -Xloggc:/log/gclogs/app-gc.log -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=15 -XX:GCLogFileSize=10M ...

11. JVM Tools

  • Java Object Layout (JOL)

    $ wget -q https://builds.shipilev.net/jol/jol-cli-latest.jar $ java -jar jol-cli-latest.jar internals java.lang.String

12. System/Node Health

  • SAR (System Activity Report)

    $ yum install sysstat $ sar -A # Generate file for single day: $ sar -A -f /var/log/sa/sa19 > /tmp/sa19_$(hostname).txt # Generate file for multiple days files: $ ls /var/log/sa/sa?? | xargs -i sar -A -f {} > /tmp/sar_$(uname -n).txt

    • https://github.com/vlsi/ksar

    • https://github.com/sargraph/sargraph.github.io

    • https://sarcharts.tuxfamily.org/

    • https://www.cyberciti.biz/tips/top-linux-monitoring-tools.html

  • Node Exporter

  • Prometheus JFR Exporter

13. Commands

  • Grabbing a file from a remote system with ssh

    # grabbing a file from a remote system with ssh but no scp binary $ ssh user@remote-system "cat <file.txt" > file.txt $ ssh user@remote-system 'tar -S cz somedirectory' | tar -S xvz # Using Rsync: Upload $ rsync -Pavze ssh path/to/src remote-system:path/to/dst # Download $ rsync -Pavze ssh remote-system:path/to/src path/to/dst

  • Strace

    # Syscall trace $ strace -tttTf -p <pid>

  • Netstat

    $ netstat -tunalp # Socket stats $ ss -s

14. Clock Cycles

CPU Clock Cycles

15. Resources

Last modified: 21 September 2024
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