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mem.go
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mem.go
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package agent
import (
"bufio"
"errors"
"fmt"
"io/ioutil"
"os"
"runtime"
"strconv"
"strings"
"github.com/sirupsen/logrus"
)
func getAvailableMemory() uint64 {
const tooBig = 322122547200 // #300GB or 0, biggest aws instance is 244GB
var availableMemory uint64 = tooBig
if runtime.GOOS == "linux" {
var err error
availableMemory, err = checkCgroup()
if err != nil {
logrus.WithError(err).Error("Error checking for cgroup memory limits, falling back to host memory available..")
}
if availableMemory >= tooBig || availableMemory <= 0 {
// Then -m flag probably wasn't set, so use max available on system
availableMemory, err = checkProc()
if availableMemory >= tooBig || availableMemory <= 0 {
logrus.WithError(err).Fatal("Cannot get the proper memory information to size server. You must specify the maximum available memory by passing the -m command with docker run when starting the server via docker, eg: `docker run -m 2G ...`")
}
}
} else {
// This still lets 10-20 functions execute concurrently assuming a 2GB machine.
availableMemory = 2 * 1024 * 1024 * 1024
}
logrus.WithFields(logrus.Fields{"ram": availableMemory}).Info("available memory")
return availableMemory
}
func checkCgroup() (uint64, error) {
f, err := os.Open("/sys/fs/cgroup/memory/memory.limit_in_bytes")
if err != nil {
return 0, err
}
defer f.Close()
b, err := ioutil.ReadAll(f)
limBytes := string(b)
limBytes = strings.TrimSpace(limBytes)
if err != nil {
return 0, err
}
return strconv.ParseUint(limBytes, 10, 64)
}
var errCantReadMemInfo = errors.New("Didn't find MemAvailable in /proc/meminfo, kernel is probably < 3.14")
func checkProc() (uint64, error) {
f, err := os.Open("/proc/meminfo")
if err != nil {
return 0, err
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
b := scanner.Text()
if !strings.HasPrefix(b, "MemAvailable") {
continue
}
// expect form:
// MemAvailable: 1234567890 kB
tri := strings.Fields(b)
if len(tri) != 3 {
return 0, fmt.Errorf("MemAvailable line has unexpected format: %v", b)
}
c, err := strconv.ParseUint(tri[1], 10, 64)
if err != nil {
return 0, fmt.Errorf("Could not parse MemAvailable: %v", b)
}
switch tri[2] { // convert units to bytes
case "kB":
c *= 1024
case "MB":
c *= 1024 * 1024
default:
return 0, fmt.Errorf("Unexpected units for MemAvailable in /proc/meminfo, need kB or MB, got: %v", tri[2])
}
return c, nil
}
return 0, errCantReadMemInfo
}