lots of org.jenkinsci.plugins.pipeline.modeldefinition.ast objects on heap

[Radoslaw Moszczynski]

Hi,

We recently upgraded to 2.504.1 and we're seeing something new in terms of memory usage, compared to what we saw on previous versions.

If I grab a heap histogram from our instance, the top 25 rows include these:

org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTKey 1,781,309 8 76,002,555 12
org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTValue$ConstantValue 1,638,513 7 69,909,920 11
org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTKeyValueOrMethodCallPair 1,280,275 6 54,625,073 8
org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTStage 535,756 2 7,619,649 1
org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTValue$GStringValue 356,297 1 15,202,023 2
org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTBuildParameter 355,548 1 15,170,050 2
org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTTreeStep 284,657 1 9,109,032 1
org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTBranch 214,622 1 9,157,217 1
org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTSingleArgument 213,434 1 9,106,528 1


That's a couple gigs worth of objects, all from org.jenkinsci.plugins.pipeline.modeldefinition.ast. I haven't seen this in the past on previous versions, so I wonder where this is coming from.

It doesn't look like a leak, because the number of instances is reduced from time to time:

[2025-06-02 Mon 15:43] org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTKey 1,801,626 8 76,869,393
[2025-06-02 Mon 16:38] org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTKey 1,801,662 8 76,870,929
[2025-06-03 Tue 08:33] org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTKey 1,801,852 8 76,879,035
[2025-06-04 Wed 13:40] org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTKey 1,802,594 8 76,910,718
[2025-06-05 Thu 09:02] org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTKey 1,803,241 8 76,938,305
[2025-06-06 Fri 08:19] org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTKey 1,804,019 8 76,971,487
[2025-06-06 Fri 14:16] org.jenkinsci.plugins.pipeline.modeldefinition.ast.ModelASTKey 1,781,309 8 76,002,555


Any ideas?


Thanks,
Radek