GOMEMLIMIT and GOGC: Tuning Go Memory Management

// GOGC=100 (default): GC triggers when heap doubles
// GOGC=50: GC triggers when heap grows 50%
// GOGC=200: GC triggers when heap triples

import "runtime/debug"

func init() {
    debug.SetGCPercent(50) // More frequent GC, less memory
}

// Or via environment:
// GOGC=50 ./myapp

import "runtime/debug"

func init() {
    // Soft memory limit - GC becomes aggressive near limit
    debug.SetMemoryLimit(1.5 * 1024 * 1024 * 1024) // 1.5GB
}

// Or via environment:
// GOMEMLIMIT=1500MiB ./myapp

# Kubernetes deployment
containers:
- name: myapp
  resources:
    limits:
      memory: 2Gi
  env:
  - name: GOMEMLIMIT
    value: "1800MiB"  # Leave headroom for OS
  - name: GOGC
    value: "100"

// Before GOMEMLIMIT, teams used "ballast":
var ballast = make([]byte, 10<<30) // 10GB unused allocation

// This tricked GC into running less often
// Now obsolete - use GOMEMLIMIT instead

# Enable GC tracing
GODEBUG=gctrace=1 ./myapp

# Output example:
# gc 5 @0.5s 2%: 0.5+2.0+0.5 ms clock, 4.0+0/2.0/0+4.0 ms cpu, 
#    4->5->2 MB, 5 MB goal, 4 P

# Meaning:
# 4->5->2 MB = heap before GC -> after GC -> live data
# 2% = percentage of CPU spent on GC