JVM Options Categorized Quick Guide | Generated by AI
In the JVM world, there are many options you can configure, and the exact set depends on the JVM implementation (HotSpot, OpenJ9, GraalVM, etc.) and version. Broadly, JVM options fall into these categories:
1. Standard Options
These are stable, cross-version options officially documented and guaranteed to work. Examples:
-classpath/-cp→ specify classpath.-Dproperty=value→ set system properties.-version→ print JVM version.-Xms/-Xmx→ initial and maximum heap size.-ea→ enable assertions.
2. Non-Standard Options (-X)
These are JVM-specific, not guaranteed to remain stable. Examples (HotSpot):
-Xint→ interpret only (no JIT).-Xcomp→ compile all methods at first use.-Xbatch→ disable background compilation.-Xss512k→ set thread stack size.
3. Advanced Options (-XX)
These provide fine-grained tuning for GC, JIT, and runtime behavior. Examples:
-XX:+UseG1GC→ enable G1 garbage collector.-XX:+PrintGCDetails→ log GC activity.-XX:MaxMetaspaceSize=256m→ cap metaspace.-XX:+HeapDumpOnOutOfMemoryError→ dump heap when OOM occurs.-XX:+UnlockExperimentalVMOptions→ allow experimental flags.-XX:+UseStringDeduplication→ reduce memory usage by deduplicating strings.
4. Diagnostic & Experimental
Some flags are hidden and require unlocking:
-XX:+UnlockDiagnosticVMOptions→ enable diagnostic flags.-XX:+UnlockExperimentalVMOptions→ allow experimental tuning.
You can then use options like:
-XX:+PrintFlagsFinal→ list all JVM options and their values.-XX:+LogCompilation→ log JIT compiler activity.
5. Tools to Work With JVM Options
java -X→ lists non-standard options for your JVM build.java -XX:+PrintFlagsFinal→ prints all recognized options with defaults and current values.jcmd <pid> VM.flags→ show JVM flags for a running process.jcmd <pid> VM.uptime,jcmd <pid> VM.system_properties→ runtime inspection.jps+jinfo→ list Java processes and print JVM options.- VisualVM / JConsole → monitor heap, GC, and runtime parameters.
👉 A practical way to explore your environment is to run:
java -XX:+PrintFlagsFinal | grep GC
to see all GC-related options, or just:
java -X
to check available non-standard flags.
Would you like me to give you a categorized cheat-sheet of the most useful JVM options (GC, memory, debugging, performance tuning) so you don’t have to parse the huge PrintFlagsFinal list?