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Tag: jvm

Jmeter Injector Heap size

We have a jmeter injector box which uses 32GB heap size for jmeter jvm. When running load tests we noticed a big dip in injecting load when GC activity happens. Anyone experienced this before? Which GC algorithm we can use here?? Answer Most probably you’re seeing so called Stop-The-World There are garbage collection algorithms like: ZGC Shenandoah C4 which can

Is JVM or JIT able to reduce duplicate method calls?

I have a function that checks if a map has some value for key (map.get(key) != null) and then returns the value, or else create new value. I’m wondering is there any JVM or JIT magic that doesn’t have to do 2 map lookups when the value exists for the given key? According to my benchmark, it seems no optimisation

How to inspect jvm module contents from the command line?

I would like to inspect the contents of a resource file of a java module of my locally installed jvm from the command line. Based on a question about mime type support in a jvm I would like to see the contents of /sun/net/www/ in module java.base of my locally installed jvm. However when scrolling through the files installed for

What is the use of the “dup2_x2” instruction in JVM bytecode?

Java has a dup2_x2 instruction which, according to the documentation, has the following behavior: Duplicate the top one or two values on the operand stack and insert the duplicated values, in the original order, into the operand stack. Does javac produce bytecode with this instruction? What are its potential use cases? Answer For example, the following code compiles to See,

Print a value of an extended class object from mother class object

I’ve declared a table that has the mother class type and i’ve filled it with many objects that have the extended classe type, everything looks fine and the table is successfully filled, the problem is when i’m trying to access to the table values i cannot ( in the exemple i’m trying to get the salaire attribut ) MOTHER CLASS