gogctest
Running it
go get && go build . && GODEBUG=gctrace=1, ./gogctest -lrusize 10000000 -addrate 10000
It needs approximately 3 GB of memory by default (modify -lrusize argument to adjust).
What is it
A small test intended to to exercise a workload that most traditional garbage collectors fail at.
It creates a number of goroutines, each having an LRU cache at a fixed size (number of entries), and indefinitely adds small items to it in a rate limited fashion.
Despite being very simple, traditional GCs tend to cause non-trivial pause times under this workload because of a combination of properties (some of which may not apply depending on GC):
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The heap size is non-trivially large.
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There are lots of tiny objects.
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There are lots of pointers.
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Many of the pointers are intergenerational/interregion (if running with such a GC).
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There is lots of pointer mutation to bold old and new pointers.
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The nature of the LRU means that objects mostly die old. This is the worst case for a generational GC.
A similar one for the JVM is at https://github.com/scode/lrugctest