denis256 notes and projects

Collection of less used parameters passed to java process.

Aggregated list of less used java parameters, may be useful in some cases.

1. -XX:OnOutOfMemoryError:

   • Usage: Specify a script or command to execute when an OutOfMemoryError occurs.
   • Example:

     java -XX:OnOutOfMemoryError="kill -9 %p"
     

     This command will kill the Java process (%p) when an OutOfMemoryError is encountered.

2. -XX:SoftRefLRUPolicyMSPerMB:

   • Usage: Adjust the soft reference LRU policy based on memory consumption.
   • Example:

     java -XX:SoftRefLRUPolicyMSPerMB=1000
     

     This sets the policy to clear soft references more aggressively when memory consumption exceeds 1000 milliseconds per MB.

3. -XX:MaxDirectMemorySize:

   • Usage: Set the maximum size of direct memory available to your application.
   • Example:

     java -XX:MaxDirectMemorySize=256m -jar myapp.jar
     

     This limits the direct memory to 256 megabytes.

4. -XX:MaxMetaspaceSize:

   • Usage: Set an upper limit on the size of the metaspace, which stores class metadata.
   • Example:

     java -XX:MaxMetaspaceSize=128m -jar myapp.jar
     

     This caps the metaspace at 128 megabytes.

5. -XX:ThreadStackSize:

   • Usage: Adjust the stack size for Java threads.
   • Example:

     java -XX:ThreadStackSize=256k -jar myapp.jar
     

     This sets the thread stack size to 256 kilobytes.

6. -XX:+UseBiasedLocking:

   • Usage: Enable biased locking, which can improve performance in some cases by reducing synchronization overhead.
   • Example:

     java -XX:+UseBiasedLocking -jar myapp.jar
     

     This enables biased locking for the application.

7. -XX:+UseLargePages:

   • Usage: Enable the use of large memory pages to improve memory management performance.
   • Example:

     java -XX:+UseLargePages -jar myapp.jar
     

     This enables large memory pages for the JVM.

8. -XX:AllocateHeapAt:

   • Usage: Specify the base address for the heap (used with certain operating systems).
   • Example:

     java -XX:AllocateHeapAt=0x0000000100000000 -jar myapp.jar
     

     This sets the base address of the heap memory.

9. -XX:FlightRecorderOptions:

   • Usage: Configure Java Flight Recorder (JFR) options for advanced profiling and diagnostics.
   • Example:

     java -XX:FlightRecorderOptions=defaultrecording=true -jar myapp.jar
     

     This enables default JFR recording.

10. -XX:MaxFDLimit:

    • Usage: Set the maximum number of file descriptors that can be opened by the JVM.
    • Example:

      java -XX:MaxFDLimit=8192 -jar myapp.jar
      

      This increases the maximum file descriptor limit to 8192 for the application.

These less commonly used Java parameters can be helpful in specific situations where fine-tuning or advanced configuration is necessary. However, they should be used with caution, as improper settings can impact application performance and stability.