Don't default to Eco JVM settings for unknown dynos #282
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edmorley
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Jan 5, 2024
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Currently, if a Dyno type cannot be determined via
ulimit -uoutput matching the JVM options forEcodynos will be used. These are the most aggressively and specifically tuned options for a low-memory environment. This PR changes this behaviour to explicitly match forEco,BasicandStandard-1Xdynos and default to using JVM ergonomics with a heap maximum of 80% of system memory.JVM ergonomics work well enough as a default for environment that are not memory constrained. In addition, JVM ergonomics are not Heroku specific and should be less surprising for customers.
We could potentially default
Performance-MandPerformance-LDynos to JVM ergonomics as well, but I decided to keep the already established defaults to avoid surprising behaviour for existing customers. The only benefit for us would be the removal of two trivial lines of code. That said, it might be worth making this change for the CNB future.I manually verified that the JVM settings on each existing Dyno type do not change between main and this PR.
Ref: GUS-W-4634736