Module: Ductwork::PollingInterval

Defined in:
lib/ductwork/polling_interval.rb

Overview

NOTE: pollers start in lockstep and stay there. A runner spawns its advancer (or worker) threads in a tight loop, so they all reach their first idle sleep within microseconds of each other, and because every subsequent sleep is the same fixed interval the phase alignment never decays on its own. Aligned pollers wake together, run the same candidate SELECT against the same rows, and all but one lose the claim race -- the very contention that sampling a candidate window in BranchClaim is meant to spread out. Spreading the wake-ups spreads the queries.

The jitter is re-rolled on every sleep rather than being a per-thread offset chosen once at startup, because a burst of work re-synchronizes the pollers no matter how they were staggered: they all stay busy while the queue drains and then all go idle together the moment it empties.

The spread is symmetric so the configured polling timeout stays the average wait. Someone who sets polling_timeout: 1 still gets a one second average poll latency instead of a quietly slower one.

Constant Summary collapse

JITTER_RATIO = 
0.25

Class Method Summary collapse

Class Method Details

.jittered(timeout) ⇒ Object 



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# File 'lib/ductwork/polling_interval.rb', line 24

def self.jittered(timeout)
  spread = timeout * JITTER_RATIO

  timeout + Kernel.rand(-spread..spread)
end