*: support cgroup with systemd (#48096)

tidb-server/main.go

@@ -197,6 +197,7 @@ func main() {
  checkTempStorageQuota()
  }
  setupLog()
+ memory.InitMemoryHook()
  setupExtensions()
 
  err := cpuprofile.StartCPUProfiler()

util/memory/meminfo.go

@@ -21,8 +21,10 @@ import (
  "github.com/pingcap/failpoint"
  "github.com/pingcap/tidb/parser/terror"
  "github.com/pingcap/tidb/util/cgroup"
+ "github.com/pingcap/tidb/util/logutil"
  "github.com/pingcap/tidb/util/mathutil"
  "github.com/shirou/gopsutil/v3/mem"
+ "go.uber.org/zap"
 )
 
 // MemTotal returns the total amount of RAM on this system
@@ -50,6 +52,10 @@ func MemTotalNormal() (uint64, error) {
  if time.Since(t) < 60*time.Second {
  return total, nil
  }
+ return memTotalNormal()
+}
+
+func memTotalNormal() (uint64, error) {
  v, err := mem.VirtualMemory()
  if err != nil {
  return v.Total, err
@@ -139,6 +145,7 @@ func MemUsedCGroup() (uint64, error) {
  return memo, nil
 }
 
+// it is for test and init.
 func init() {
  if cgroup.InContainer() {
  MemTotal = MemTotalCGroup
@@ -162,6 +169,36 @@ func init() {
  terror.MustNil(err)
 }
 
+// InitMemoryHook initializes the memory hook.
+// It is to solve the problem that tidb cannot read cgroup in the systemd.
+// so if we are not in the container, we compare the cgroup memory limit and the physical memory,
+// the cgroup memory limit is smaller, we use the cgroup memory hook.
+func InitMemoryHook() {
+ if cgroup.InContainer() {
+ logutil.BgLogger().Info("use cgroup memory hook because TiDB is in the container")
+ return
+ }
+ cgroupValue, err := cgroup.GetMemoryLimit()
+ if err != nil {
+ return
+ }
+ physicalValue, err := memTotalNormal()
+ if err != nil {
+ return
+ }
+ if physicalValue > cgroupValue && cgroupValue != 0 {
+ MemTotal = MemTotalCGroup
+ MemUsed = MemUsedCGroup
+ logutil.BgLogger().Info("use cgroup memory hook", zap.Int64("cgroupMemorySize", int64(cgroupValue)), zap.Int64("physicalMemorySize", int64(physicalValue)))
+ } else {
+ logutil.BgLogger().Info("use physical memory hook", zap.Int64("cgroupMemorySize", int64(cgroupValue)), zap.Int64("physicalMemorySize", int64(physicalValue)))
+ }
+ _, err = MemTotal()
+ terror.MustNil(err)
+ _, err = MemUsed()
+ terror.MustNil(err)
+}
+
 // InstanceMemUsed returns the memory usage of this TiDB server
 func InstanceMemUsed() (uint64, error) {
  used, t := serverMemUsage.get()