Projects leak in ExternalIndexableSetContributor.CACHE

[ibessonov]

Prerequisites

• Plugin is in the latest version
• Issue was not reported yet
• Stack trace (if provided) contains mobi.hsz.idea.gitignore package name

Description

ExternalIndexableSetContributor.CACHE contains disposed projects in memory dump. This causes memory leaks and increases GC time.

Problem was discovered while inspecting this issue: https://youtrack.jetbrains.com/issue/IDEA-192493

[hsz]

@ibessonov Thank you for creating this issue. I have no access to the linked ticket:

You have no permissions to view this page

Anyway, I've reviewed the code and ExternalIndexableSetContributor.invalidateCache(Project) is invoked always when the IgnoreManager project component is disposed (which is disposed when project is disposed).

[ibessonov]

Hi @hsz, I see invalidation in IgnoreManager, but at the same time I see disposed projects in CACHE map in ExternalIndexableSetContributor. I'm confused to be honest. You can investigate this dump:
ftp://ftp.intellij.net/.uploads/damien-sorel-dump-and-logs-2018-06-29.zip, you'll find disposed IgnoreManager objects with disposed projects but valid cache.

Can it be that ExternalIndexableSetContributor#getAdditionalFiles is invoked after disposal? It would create empty values in CACHE.

[hsz]

@ibessonov File is not available via the provided URL.

[hsz]

@ibessonov I have checked the code again and it's almost impossible to have disposed projects in this map. Maybe there is some border case or issue in IDE SDK - who knows.
I did the additional check on project open/close - so if there will be new project opened or previous closed - it'll iterate through CACHE and remove all disposed entries from map.

[ibessonov]

Thank you!
Sorry that I didn't provide valid dump, I completely forgot that "ftp.intellij.net" is a write-only service for anonymous users. I wasn't able to reproduce this issue myself, it's clearly some border case. It probably occurs under high loads or in some rare data races.