🧰🔍 JDK BIN TOOLS YOU FORGOT YOU HAD (AND THE ONES ADDED/EVOLVED AFTER 2020)
🧰🔍 JDK BIN TOOLS YOU FORGOT YOU HAD (AND THE ONES ADDED/EVOLVED AFTER 2020)
🔸 TL;DR
The JDK ships a seriously underrated toolbox in JAVA_HOME/bin: process discovery (jps), bytecode peeking (javap), heap/thread forensics (jmap/jstack), JMX GUIs (jconsole), plus modern “do-it-all” tooling like jcmd and jfr. Bonus: newer JDKs also brought handy utilities like jwebserver.
🔸 THE “CLASSIC” DIAGNOSTIC CREW
▪️ jps – list JVM processes (often step #1 to get the PID)
▪️ javap – disassemble .class files (bytecode + signatures): “what did the compiler really generate?”
▪️ jmap – heap histogram / heap dump (.hprof) for memory investigations
▪️ jinfo – JVM flags + system properties for a running process
▪️ jstack – thread dumps: deadlocks, blocked threads, hotspots
▪️ jconsole – built-in JMX UI: threads, memory, GC, MBeans
🔸 THE MODERN MVP: JCMD
If you remember only one: jcmd. It’s the Swiss Army knife that can trigger many diagnostics from a single entry point.
▪️ Examples you’ll actually use:
▪️ jcmd VM.flags → runtime flags
▪️ jcmd VM.system_properties → system props
▪️ jcmd Thread.print → thread dump-style output
▪️ jcmd GC.heap_info → heap overview
▪️ jcmd GC.class_histogram → quick memory signal
🔸“NEW SCHOOL” BIN TOOLS WORTH KNOWING
▪️ jfr – Java Flight Recorder CLI (recordings, summaries, inspection)
▪️ jwebserver – instant static file server for quick demos/tests
▪️ jpackage – build native installers/packages for Java apps
▪️ jdeps – dependency analyzer (great for modularization and classpath sanity)
▪️ jdeprscan – scan jars/classes for deprecated Java SE API usage
▪️ jhsdb – HotSpot/serviceability debugging (deeper JVM forensics)
🔸 TAKEAWAYS
▪️ My go-to triage flow: jps → jcmd → (jstack/jmap) → jfr 🧯
▪️ jcmd reduces tool-hopping: one entry point, many diagnostics 🧰
▪️ jfr is a game-changer when you need real signal with low overhead 📈
▪️ GUI lovers: jconsole is there; VisualVM is a separate install 🖥️
▪️ Modern JDKs quietly got more “ops-friendly” than most devs realize 🚀
#java #jdk #openjdk #jvm #performance #observability #profiling #jfr #debugging #devops #sre #springboot
Go further with Java certification:
Java👇
Spring👇
SpringBook👇