high usage of metaspace after upgrade to 4.22.0

[andre-pt]

Hi,

we had an application for some years working with 4.14.0 and today we rolled out an update to 4.22.0.

We noticed instances getting java.lang.OutOfMemoryError: Metaspace and started investigating.

Metaspace usage was constant before this update and now we had to increase it to avoid running into OutOfMemory:

We also noticed that loaded classes increased significantly:

We are using the following 2 methods:

    public static String toJson(Object o) {
        return JsonIo.toJson(o, null);
    }

    public static <T> T toObject(String json, Class<T> rootType) {
        return JsonIo.toObjects(json, null, rootType);
    }

Is this behavior expected? Is there anything we can do to limit the usage of metaspace?

Thanks a lot Andre

[andre-pt]

I just noticed a huge performance improvement by reusing the ReadOptions and WriteOptions:

    private static final WriteOptions DEFAULT_WRITE_OPTIONS = new WriteOptionsBuilder().build();
    private static final ReadOptions DEFAULT_READ_OPTIONS = new ReadOptionsBuilder().build();

    public static String toJson(Object o) {
        return JsonIo.toJson(o, DEFAULT_WRITE_OPTIONS);
    }

    public static <T> T toObject(String json, Class<T> rootType) {
        return JsonIo.toObjects(json, DEFAULT_READ_OPTIONS, rootType);
    }

We will try this on production and I will report back

[andre-pt]

my previous solution resolved the metaspace usage issue.

[jdereg]

Andre, thank you for posting your ReadOptions/WriteOptions journey. You are absolutely correct in your conclusion, a ReadOptions / WriteOptions instance should be created and held onto. I will make sure our documentation is more clear on that. Thank you again for your posts.

[andre-pt]

Hey As an alternative, you could make a singleton or a static default object used when the parameter is null It would avoid issues for less careful users like me.

Additionally we are experiencing a memory leak in LRUCache class. I will investigate more next week, but it's very similar to what's described here: https://hoangx281283.wordpress.com/2012/11/18/wrong-use-of-linkedhashmap-causes-memory-leak/

Andre

On Fri, May 31, 2024, 16:59 John DeRegnaucourt @.***> wrote:

Andre, thank you for posting the journey you made. You are absolutely correct in your conclusion, that the intention is that we expect a ReadOptions instance and a WriteOptions instance should be created and held onto. I will make sure our documentation is more clear on that. Thank you again for your posts.

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