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 garb…
Tag: jvm
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 …
Does survivol spaces get garbage collected before moving to the old generation?
I understand that when the Eden is full, a minor garbage collection is done. Surviving objects go to the survivol spaces. These objects will eventually arrive to the old generation. Does the objects in the survivol spaces get garbage collected as well, or they will just be moved to the tenure generation and b…
When not to use volatile，it still can see the changes which issued by other thread
if it does not have the following codes, it will not show “end”. if it has these codes, it will probably show “end”. Sometimes it does not show. when is less than 598 or not have these codes, like use 550, it will not show “end”. when is 598, it will probably show “en…
Why the java.lang.CharacterDataLatin1#digit function in JDK generates the whole digit byte array?
In the source code, it says that: Analysis has shown that generating the whole array allows the JIT to generate better code compared to a slimmed down array, such as one cutting off after ‘z’ So my questions are: What’s the root reason of this comment? Compared to the slimmed down array, how…
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/content-types.properties in module java.base of my locally installed jvm. However wh…
JVM: Non-heap memory causes OutOfMemoryError because the Garbage Collector is not run. What am I doing wrong?
I’ve encountered a weird issue where the Groovy application I’m working on grows to consume more memory (far beyond the limits of the xmx-argument, so it can’t be the heap) until the computer runs out of RAM, at which point the JVM behaves in one of two different ways – it either sudde…
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 …
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…
What exactly happens in the JVM when invoking an object’s instance method?
I think I have finally found out how to word, what is giving me so much trouble in understanding: how the virtual machine can access a classes methods and use it only on a given instance (object) with the catch that the virtual machine is only being given the reference/pointer variable. This was compounded by…