README
¶
gctuner
Introduction
Inspired by How We Saved 70K Cores Across 30 Mission-Critical Services (Large-Scale, Semi-Automated Go GC Tuning @Uber) .
_______________ => limit: host/cgroup memory hard limit
| |
|---------------| => gc_trigger: heap_live + heap_live * GCPercent / 100
| |
|---------------|
| heap_live |
|_______________|
Go runtime trigger GC when hit gc_trigger which affected by GCPercent and heap_live.
Assuming that we have stable traffic, our application will always have 100 MB live heap, so the runtime will trigger GC
once heap hits 200 MB(by default GOGC=100). The heap size will be changed like: 100MB => 200MB => 100MB => 200MB => ....
But in real production, our application may have 4 GB memory resources, so no need to GC so frequently.
The gctuner helps to change the GOGC(GCPercent) dynamically at runtime, set the appropriate GCPercent according to current memory usage.
How it works
_______________ => limit: host/cgroup memory hard limit
| |
|---------------| => threshold: increase GCPercent when gc_trigger < threshold
| |
|---------------| => gc_trigger: heap_live + heap_live * GCPercent / 100
| |
|---------------|
| heap_live |
|_______________|
threshold = inuse + inuse * (gcPercent / 100)
=> gcPercent = (threshold - inuse) / inuse * 100
if threshold < 2*inuse, so gcPercent < 100, and GC positively to avoid OOM
if threshold > 2*inuse, so gcPercent > 100, and GC negatively to reduce GC times
Usage
The recommended threshold is 70% of the memory limit.
// Get mem limit from the host machine or cgroup file.
limit := 4 * 1024 * 1024 * 1024
threshold := limit * 0.7
gctuner.Tuning(threshold)
// Friendly input
gctuner.TuningWithFromHuman("1g")
// Auto
// There may be problems with multiple services in one pod.
gctuner.TuningWithAuto(false) // Is it a container? Incoming Boolean
Documentation
¶
Overview ¶
Package gctuner implements https://github.com/bytedance/gopkg
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func GetMaxGCPercent ¶
func GetMaxGCPercent() uint32
GetMaxGCPercent returns the max gc percent value.
func GetMinGCPercent ¶
func GetMinGCPercent() uint32
GetMinGCPercent returns the min gc percent value.
func SetMaxGCPercent ¶
SetMaxGCPercent sets the new max gc percent value.
func SetMinGCPercent ¶
SetMinGCPercent sets the new min gc percent value.
func Tuning ¶
func Tuning(threshold uint64)
Tuning sets the threshold of heap which will be respect by gc tuner. When Tuning, the env GOGC will not be take effect. threshold: disable tuning if threshold == 0
func TuningWithAuto ¶
func TuningWithAuto(isContainer bool)
TuningWithAuto By automatic calculation of the total amount
func TuningWithFromHuman ¶
func TuningWithFromHuman(threshold string)
TuningWithFromHuman eg. "b/B", "k/K" "kb/Kb" "mb/Mb", "gb/Gb" "tb/Tb" "pb/Pb".
Types ¶
This section is empty.
Source Files