SURVIVOR | playable HTML CSS JavaScript remake | Game Engine library

The problem here is that jvmMemPoolMaxSize (OID .1.3.6.1.4.1.42.2.145.3.163.1.1.2.110.1.13) is defined in JVM-MANAGEMENT-MIB as type JvmUnsigned64TC, which seems kind of strange because Java specifically forbids the use of unsigned integer types.

The description for jvmMemPoolMaxSize implies that it's meant to represent the value returned by java.lang.management.MemoryPoolMXBean.getUsage().getMax(). The documentation for that method says "This method returns -1 if the maximum memory size is undefined."

The description of jvmMgmMIB addresses the issue with this explanation:

Where the Java programming language API uses long, or int, the MIB often uses the corresponding unsigned quantity - which is closer to the object semantics.

In those cases, it often happens that the -1 value that might be used by the API to indicate an unknown/unimplemented value cannot be used. Instead the MIB uses the value 0, which stricly speaking cannot be distinguished from a valid value. In many cases however, a running system will have non-zero values, so using 0 instead of -1 to indicate an unknown quantity does not lose any functionality.

I think it's safe to say this is one of the cases where a zero is not valid, so you should take it to mean that there is no defined maximum.

You just have to rename the column axis:

The allocated size listed in that table includes Metaspace. Metaspace is memory pool separate from the java object heap. Therefore the sum of heap and metaspace can exceed the maximum heap size.

Solved. i changed my code to like this and it work.

what is the unit here

A region. Region size varies based on heap size or an explicit setting.

it also looks like this happens almost entirely within the Eden regions - so the objects already went out of scope before even moving to the survivor space?

Most of them, a small amount might still trickle into later generations but on the other hand those regions may also contain now-dead objects that can be collected so it's mostly in equilibrium with only a very small flow towards the old generation. This kind of behavior is what makes generational collectors so efficient.

These are not comparing the same thing.

When running jmap or jstack, these attach to the existing process with PID 9, as listed in the first jps command.

When running java -XX:+PrintFlagsFinal -version, this creates a new JVM process, and prints the information for that new process. Note that the original PID 9 process has a number of additional flags that can affect the calculated heap size.

For a more accurate comparison, you could add the -XX:+PrintFlagsFinal flags to the main command run when the container starts. I would expect this to match the values returned by jinfo and jmap.

Looks like the else branch of if 'description' in dic: is never executed. If your code is indented correctly, then also the csvWriter.writerow part is never executed because of this.

That yields that no contents are written to your file.

A comment on code style:

• use with open(file) as file_variable: instead of manually using open and close. That can save you some trouble, e.g. the trouble you would get when the else branch would indeed be executed and the file would be closed multiple times :)

I believe the problem relies in the append_to_csv function because of a wrong indentation.

Look at your code: