[BUG] MetadataImage leak or hold ref too long cause oom

[lifepuzzlefun]

Version & Environment

1.2

What went wrong?

MetadataImage leak

What should have happened instead?

no leak

How to reproduce the issue?

have no idea

Additional information

log missing.

only heapdump 24G if needed

[lifepuzzlefun]

I wonder if StreamMetadataManager.fetch0 may hold one ref of Image at epoch of 29 for very long time.

[super-213]

possible causes:

1. metadata images are cached without an appropriate eviction policy.

2. old references are not cleaned up during metadata updates or epoch changes.

3. some long-lived objects hold strong references to these images.

4. metadata image objects are no longer in use but are still held by a chain of references.

solution

1. add epoch-aware cleanup mechanism

`public void onEpochChange(int newEpoch) {

for (Iterator<Map.Entry<String, MetadataImage>> it = imageCache.entrySet().iterator(); it.hasNext();) {

    Map.Entry<String, MetadataImage> entry = it.next();

    if (entry.getValue().getEpoch() < newEpoch) {

        it.remove();

    }

}

}`

2. use WeakHashMap instead of ordinary HashMap
3. add regularly executed cleanup tasks