While going through the heap dump - seeing duplicate java.lang.invoke.LambdaForm class instance. Please find attached.
Related
created a script with this configuration:
Number of threads (users) - 200 users
Duration assertion - 3 seconds
Ramp-up period - 10 seconds
Think time - 2 seconds
Jmeter version 5.2.1
Java 8
Laptop configuration:
Microsoft windows 10
Intel i7 processor
RAM 16gb
I also increased the size of the memory to 1024m in batch file
: "${HEAP:="-Xms1g -Xmx1g -XX:MaxMetaspaceSize=1024m"}"
Still I am facing the out of memory issue. can you please help me out
As per Java command line arguments
-XX:MaxMetaspaceSize=size
Sets the maximum amount of native memory that can be allocated for class metadata. By default, the size is not limited. The amount of metadata for an application depends on the application itself, other running applications, and the amount of memory available on the system.
So if you're getting java.lang.OutOfMemoryError: Metaspace error you need to either increase the metaspace size more or just remove this parameter from the JVM arguments so it will be unlimited.
Most probably you're getting java.lang.OutOfMemoryError: Java heap space, if this is the case - you need to increase the -Xmx1g to somewhat bigger, i.e. -Xmx4g
Actually OutOfMemoryError exception has many faces so it's not possible to provide exact steps for this without seeing the full output from stdout/stderr/jmeter.log file/ .hprof file
See 9 Easy Solutions for a JMeter Load Test “Out of Memory” Failure article for more JMeter tuning tips.
I run peak test in Jmeter, got OOM error, but when i add the heap size in Jmeter.bat file, it still got OOM error. My PC is RAM is 16G, updated the max heap to 8G. Below are my updated jmeter.bat file.
set HEAP=-Xms3g -Xmx8g -XX:MaxMetaspaceSize=5120m
OutOfMemoryError can have many faces, it is not necessarily the lack of heap space, the other reasons could be in:
GC Overhead Limit Exceeded when the garbage collector is running and the program itself is not (or very slow)
Requested array size exceeds VM limit when you try to allocate too large objects
Unable to Create New Native Thread when it is not possible to create a thread due to underlying operating system limits
etc.
Not knowing the details of your test plan and not seeing the full jmeter.log file (preferably with debug logging enabled) it is not possible to come up with the comprehensive answer, going forward consider including more details as "OOM" doesn't tell anything to us.
I am getting metaspace issue in Wildfly.
Currently XX:MaxMetaspaceSize is 256M. But i am getting following issue multiple times in multiple server groups in different projects (50 projects in total distributed among server groups). And facing following exception daily.
failed to define class: OutOfMemoryException: Metaspace
Most of posts(stackoverflow and others) suggest it should be 2GB in case of wildfly.
But i have read in various article which suggests that in Java 8 there is no need to increasing Metaspace:
In Java 8, the metaspace that holds your classes can expand without limit by default,
Could you please resolve this confusion that - if Metaspace is automatically increased and suppose i have set 256 then does it not automatically increase? What benefit i will get at 2G.
Per the Oracle docs, in Java 8, the class metadata is stored in native memory and by default is unlimited. MaxMetaspaceSize puts an upper limit on the native memory that's used for class metadata.
If you also have UseCompressedOops and UseCompressedClassesPointers enabled, then MaxMetaspaceSize sets the upper limit on the sum of both areas of native memory used for class metadata - the area for the compressed class metadata, and the area for all other class metadata.
Also, 2GB sounds a bit high. I would slowly increase and test to be sure you're setting this to an optimal value for your needs.
What condition triggers the garbage collection of Metaspace when MaxMetaspaceSize property is not set on the jvm.
Say if i close few unused classloaders there is a scope to free up the memory in the metaspace memory. My questions is does the full gc trigger the cleanup of metaspace memory or is it triggered in some other way.
since by default Metaspace in Java 8 is not limited, when does jvm understands that it need to clean up the unreferenced classes from its metaspace.
Metaspace itself is not garbage-collected. But the java heap is. When java.lang.Class objects get collected the underlying metadata gets freed too. So in most circumstances regular GC cycles will also free up metaspace if there are any classes that are eligible for unloading.
but want to understand when does the gc get triggered to cleanup the metaspace memory of the undeployed apps.
At the latest when the current capacity of the metaspace is full, possibly earlier when regular garbage collections unload classes.
Yes, it's the full GC that cleans up the metaspace, specifically you should see entries like this Full GC (Metadata GC Threshold) after enabling verbose mode on the gc.
It's clearly documented here, I may just quote it here.
-XX:MetaspaceSize=size
Sets the size of the allocated class metadata space that will trigger a garbage collection the first time it is exceeded. This threshold for a garbage collection is increased or decreased depending on the amount of metadata used. The default size depends on the platform.
direct quote but the emphasis is mine ;)
Might be helpful to check the answer from #Holger.
Pls use System.gc() or Runtime.gc()
Is native memory (Metaspace) for a java application gets space from heap memory or there is completely a different set of memory dedicated for it?
I think it uses the memory which is used by OS to manage all their applications, but not clear.
Java Heap Space
Java Heap space is used by java runtime to allocate memory to Objects and JRE classes. Whenever we create any object, it’s always created in the Heap space. Garbage Collection runs on the heap memory to free the memory used by objects that doesn’t have any reference. Any object created in the heap space has global access and can be referenced from anywhere of the application.
Java Stack Memory
Java Stack memory is used for execution of a thread. They contain method specific values that are short-lived and references to other objects in the heap that are getting referred from the method. Stack memory is always referenced in LIFO (Last-In-First-Out) order. Whenever a method is invoked, a new block is created in the stack memory for the method to hold local primitive values and reference to other objects in the method. As soon as method ends, the block becomes unused and become available for next method. Stack memory size is very less compared to Heap memory.
Difference between Java Heap Space and Stack Memory
Heap memory is used by all the parts of the application whereas stack memory is used only by one thread of execution.
Whenever an object is created, it’s always stored in the Heap space and stack memory contains the reference to it. Stack memory only contains local primitive variables and reference variables to objects in heap space.
Objects stored in the heap are globally accessible whereas stack memory can’t be accessed by other threads.
Memory management in stack is done in LIFO manner whereas it’s more complex in Heap memory because it’s used globally. Heap memory is divided into Young-Generation, Old-Generation etc, more details at Java Garbage Collection.
Stack memory is short-lived whereas heap memory lives from the start till the end of application execution.
We can use -Xms and -Xmx JVM option to define the startup size and maximum size of heap memory. We can use -Xss to define the stack memory size.
When stack memory is full, Java runtime throws java.lang.StackOverFlowError whereas if heap memory is full, it throws java.lang.OutOfMemoryError: Java Heap Space error.
Stack memory size is very less when compared to Heap memory. Because of simplicity in memory allocation (LIFO), stack memory is very fast when compared to heap memory.
Reference:
Java Heap Space vs Stack – Memory Allocation in Java
Java (JVM) Memory Model – Memory Management in Java
This is the basic of Java Memory Management but going through the reference material should give you comprehensive idea.
Edit
Thanks to #rajvineet to pointing out to this great article on how the JVM uses native memory on Windows and Linux. Specially the section, how the Java runtime uses native memory describes everything clearly.