The main thread polls nativeCallMessagesFromMainThread 146k times a second
with nothing to do. Between polls it now rests 100 us: nanosleep when the
governor is performance, TPAUSE (C0.2) when the CPU has WAITPKG, a spin
otherwise. Sleeping under a power-saving governor lets the render thread's
core clock down and drops frames, which is why TPAUSE is the default there.
MOCKTAIL_ENGINE_PUMP_REST=sleep|tpause|spin overrides. The profile trace
gains a slice for pumps that ran a message.
ETC2 uploads read bufferRowLength/bufferImageHeight instead of assuming
packed rows. MakeFileObject retains the path field. The main-thread pump
caches its JNI attach, but not the GetJNIEnv fallback, so a VM swap retries.
An idle launch-broker drain skips both locks.
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