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cmd/utils: size Go memory limit from cgroup-aware limit

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jonny rhea 2026-07-09 16:46:22 -05:00
parent a61099fe36
commit ca3a72e8c2
1 changed files with 16 additions and 25 deletions
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41
cmd/utils/flags.go
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@ -1771,32 +1771,23 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *ethconfig.Config) {
// burned ~20% of CPU on `runtime.scanobject`/`gcDrain`/`findObject`
// (confirmed by CPU profile of newPayload).
//
// Modern Go (1.19+) supports SetMemoryLimit, which lets the runtime
// keep GOGC at the default 100 (fewer/larger collections) while still
// guaranteeing memory stays below a soft cap. We size the cap so it's
// large enough that GOGC=100 governs steady-state behavior, but the
// limit kicks in if real memory pressure appears.
cache := ctx.Int(CacheFlag.Name)
var memLimit int64
if mem, memErr := gopsutil.VirtualMemory(); memErr == nil && mem.Total > 0 {
// Leave half the host memory for the OS / page cache / other
// processes; cap the rest at roughly 4× the configured DB cache
// to avoid runaway growth on machines with lots of RAM but a
// modest --cache.
halfHost := int64(mem.Total / 2)
fourCache := int64(cache) * 4 * 1024 * 1024
memLimit = min(halfHost, fourCache)
} else {
// Fallback when the host's total memory isn't reportable.
memLimit = int64(cache) * 4 * 1024 * 1024
// Modern Go (1.19+) supports SetMemoryLimit, which lets the runtime keep
// GOGC at the default 100 (fewer/larger collections) while still keeping
// memory below a soft cap. We size the cap from the same cgroup-aware
// limit used for the cache sanitizer above (total), so it's large enough
// that GOGC=100 governs steady state but the limit engages under real
// memory pressure. When the effective limit can't be determined, leave
// Go's defaults untouched.
if total > 0 {
cache := int64(ctx.Int(CacheFlag.Name)) * 1024 * 1024
// Target ~4× the cache so GOGC=100 governs steady state, but cap at
// half of memory. The rest is for the OS, page cache, and off-heap
// caches like Pebble that SetMemoryLimit doesn't count.
memLimit := min(int64(total)/2, cache*4)
log.Debug("Setting Go memory limit", "MB", memLimit/1024/1024, "source", source)
godebug.SetMemoryLimit(memLimit)
godebug.SetGCPercent(100)
}
if memLimit < int64(cache)*1024*1024*2 {
// Always allow at least 2× the cache so the cache itself fits.
memLimit = int64(cache) * 1024 * 1024 * 2
}
log.Debug("Setting Go memory limit", "MB", memLimit/1024/1024)
godebug.SetMemoryLimit(memLimit)
godebug.SetGCPercent(100)
if ctx.IsSet(SyncTargetFlag.Name) {
cfg.SyncMode = ethconfig.FullSync // dev sync target forces full sync