Try: import java.lang.management.ManagementFactory; import java.lang.management.RuntimeMXBean; import java.util.List; public void runtimeParameters() { RuntimeMXBean bean = ManagementFactory.getRuntimeMXBean(); List<String> aList = bean.getInputArguments(); for (int i = 0; i < aList.size(); i++) { System.out.println( aList.get( i ) ); } } That should show all JVM parameters. Note: we do not have JVM parameter in VCS either, but in a … Read more
I have not dug up the Java Language Specification, but I’d guess that it has to do with this difference: i++ < (Integer.MAX_VALUE – 1) never overflows. Once i reaches Integer.MAX_VALUE – 1 it is incremented to Integer.MAX_VALUE and then the loop terminates. i++ < Integer.MAX_VALUE contains an integer overflow. Once i reaches Integer.MAX_VALUE, it … Read more
JRockit was originally developed by Appeal and BEA Systems before being acquired by Oracle to run server software.1 It was meant to be optimized for large applications requiring long running tasks, a lot of memory and a scalable environment, pushing optimizations for these scenarios even further than the Sun HotSpot JVM in server-mode (see also: … Read more
-XX:PermSize specifies the initial size that will be allocated during startup of the JVM. If necessary, the JVM will allocate up to -XX:MaxPermSize.
One important point is that Mission Control is potentially not free to use on production environments. It is free for applications running in DEV & QA and Oracle are not currently enforcing the charges for production applications (as of Nov 2014). However, their executives have made it clear this may change in time.
Most HotSpot JVM in the last year have had it on by default. This option allows references to be 32-bit in a 64-bit JVM and access close to 32 GB of heap. (more than 32-bit pointers can) (You can have near unlimited off heap memory as well). This can save a significant amount of memory … Read more
ReservedCodeCacheSize (and InitialCodeCacheSize) is an option for the (just-in-time) compiler of the Java Hotspot VM. Basically it sets the maximum size for the compiler’s code cache. The cache can become full, which results in warnings like the following: Java HotSpot(TM) 64-Bit Server VM warning: CodeCache is full. Compiler has been disabled. Java HotSpot(TM) 64-Bit Server … Read more
jmap vs. jmap -F, as well as jstack vs. jstack -F use completely different mechanisms to communcate with the target JVM. jmap / jstack When run without -F these tools use Dynamic Attach Mechanism. This works as follows. Before connecting to Java process 1234, jmap creates a file .attach_pid1234 at the working directory of the … Read more
The definition of what exactly is a Java Virtual Machine is stated in the Java Virtual Machine Specification The JVM is by definition a virtual machine, i.e. a software machine that simulates what a real machine does. Like a real machine, it has an instruction set, a virtual computer architecture and an execution model. It … Read more
⚠️ For JetBrains IntelliJ IDEA: Go to Help -> Edit Custom Properties…. Create the file if it asks you to create it. To disable the error message paste the following to the file you created: idea_rt idea.no.launcher=true This will take effect on the restart of the IntelliJ.