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Clean up wasm cache entries based on irreversibility & fix wavm module cleanup #6983
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When we instantiate a wasm with wavm we get back a ModuleInstance. But deleting this object is a noop because wavm has its own garpage collection thing. Implement the code to interface with the garbage collection so that deleting a ModuleInstance can really free up the objects that are associated with it
previously wasm cache entries would remain indefinitely, becoming a sort of "memory leak". This is a naive change that cleans up entries once a replacement has occured and passed irreversiblity
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superseded by other PRs |
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Change Description
wasm cache entries have previously remained indefinitely creating a sort of memory leak. If using the wavm runtime this also creates a performance drag. This change is a naive fix to clean the wasm cache. It improves upon #2701 in that it waits for irreversibility before cleaning the cache (reducing cache thrashing around forks), and it also implements the garbage collection tracking for wavm so that wavm will actually free its instances.
Unfortunately there are still problems with this naive approach that makes this change not acceptable. For one, code instantiated on a fork that is thrown out is never pruned. More severely, code that is shared by multiple accounts tends to be overly pruned because getting a reference count of code used upon nodeos startup is required to avoid that.
This is mainly be put up as draft at this time to judge improvement with #6909. Unfortunately we still leave a lot of performance on the table with wavm (nearly 50%) even with this fix but it should at least not grind to a halt any longer.
Consensus Changes
API Changes
Documentation Additions