RFR: 8003246: Add Supplier to ThreadLocal (original) (raw)

Vitaly Davidovich vitalyd at gmail.com
Thu Dec 6 12:12:11 UTC 2012

Understood - I'm just trying to make sure I don't have the wrong mental model of this in my mind. Taking pathology aside (e.g. code cache is full when time to recompile, poor tiering interaction, etc), I'd expect the fast inlined path to be restored assuming call site type profile (of the ones we care about) doesn't change after other subclasses are loaded. Would be good if someone can correct that if it's inaccurate. Apologies if this is slightly hijacking the thread, but it's Remi's fault :).

Sent from my phone On Dec 6, 2012 7:03 AM, "Doug Lea" <dl at cs.oswego.edu> wrote:

On 12/06/12 06:56, Vitaly Davidovich wrote:

Doug,

When you see the fast to slow ThreadLocal transition due to class loading invalidating inlined get(), do you not then see it get restored back to fast mode since the receiver type in your call sites is still the monomorphic ThreadLocal (and not the unrelated subclasses)? Just trying to understand what Rémi and you are saying.

The possible outcomes are fairly non-deterministic, depending on hotspot's mood about recompiles, tiered-compile interactions, method size, Amddahl's law interactions, phase of moon, etc. (In j.u.c, we have learned that our users appreciate things being predictably fast enough rather than being unpredictably sometimes even faster but often slower. So when we see such cases, as with ThreadLocal, they get added to todo list.) -Doug

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