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resizer.go
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resizer.go
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package pond
import (
"runtime"
)
var maxProcs = runtime.GOMAXPROCS(0)
// Preset pool resizing strategies
var (
// Eager maximizes responsiveness at the expense of higher resource usage,
// which can reduce throughput under certain conditions.
// This strategy is meant for worker pools that will operate at a small percentage of their capacity
// most of the time and may occasionally receive bursts of tasks. It's the default strategy.
Eager = func() ResizingStrategy { return RatedResizer(1) }
// Balanced tries to find a balance between responsiveness and throughput.
// It's suitable for general purpose worker pools or those
// that will operate close to 50% of their capacity most of the time.
Balanced = func() ResizingStrategy { return RatedResizer(maxProcs / 2) }
// Lazy maximizes throughput at the expense of responsiveness.
// This strategy is meant for worker pools that will operate close to their max. capacity most of the time.
Lazy = func() ResizingStrategy { return RatedResizer(maxProcs) }
)
// ratedResizer implements a rated resizing strategy
type ratedResizer struct {
rate uint64
hits uint64
}
// RatedResizer creates a resizing strategy which can be configured
// to create workers at a specific rate when the pool has no idle workers.
// rate: determines the number of tasks to receive before creating an extra worker.
// A value of 3 can be interpreted as: "Create a new worker every 3 tasks".
func RatedResizer(rate int) ResizingStrategy {
if rate < 1 {
rate = 1
}
return &ratedResizer{
rate: uint64(rate),
}
}
func (r *ratedResizer) Resize(runningWorkers, minWorkers, maxWorkers int) bool {
if r.rate == 1 || runningWorkers == 0 {
return true
}
r.hits++
return r.hits%r.rate == 1
}