From ad436757c3162ee62c0c794d7db0af5ccf4d134c Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Fri, 28 Jun 2019 15:34:24 +0300
Subject: [PATCH] lib/memory: an attempt to read proper memory limit inside LXC
container
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/84
---
lib/memory/memory_linux.go | 48 +++++++++++++++++++++++++++------
lib/memory/memory_linux_test.go | 19 +++++++++++++
2 files changed, 59 insertions(+), 8 deletions(-)
create mode 100644 lib/memory/memory_linux_test.go
diff --git a/lib/memory/memory_linux.go b/lib/memory/memory_linux.go
index 4dc3510fb3..5e75eb33d0 100644
--- a/lib/memory/memory_linux.go
+++ b/lib/memory/memory_linux.go
@@ -2,6 +2,7 @@ package memory
import (
"io/ioutil"
+ "os/exec"
"strconv"
"syscall"
@@ -19,17 +20,48 @@ func sysTotalMemory() int {
// See https://stackoverflow.com/questions/42187085/check-mem-limit-within-a-docker-container .
data, err := ioutil.ReadFile("/sys/fs/cgroup/memory/memory.limit_in_bytes")
if err != nil {
- return totalMem
+ // Try determining the amount of memory inside lxc container.
+ mem, err := readLXCMemoryLimit(totalMem)
+ if err != nil {
+ return totalMem
+ }
+ return mem
}
- for len(data) > 0 && data[len(data)-1] == '\n' {
- data = data[:len(data)-1]
- }
- mem, err := strconv.Atoi(string(data))
+ mem, err := readPositiveInt(data, totalMem)
if err != nil {
return totalMem
}
- if mem > totalMem {
- mem = totalMem
- }
return mem
}
+
+func readLXCMemoryLimit(totalMem int) (int, error) {
+ // Read memory limit according to https://unix.stackexchange.com/questions/242718/how-to-find-out-how-much-memory-lxc-container-is-allowed-to-consume
+ // This should properly determine the limit inside lxc container.
+ // See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/84
+ cmd := exec.Command("/bin/sh", "-c",
+ `cat $(mount | grep cgroup | grep memory | cut -d" " -f3)$(cat /proc/self/cgroup | grep memory | cut -d: -f3)/memory.limit_in_bytes`)
+ data, err := cmd.Output()
+ if err != nil {
+ return 0, err
+ }
+ return readPositiveInt(data, totalMem)
+}
+
+func readPositiveInt(data []byte, maxN int) (int, error) {
+ for len(data) > 0 && data[len(data)-1] == '\n' {
+ data = data[:len(data)-1]
+ }
+ n, err := strconv.ParseUint(string(data), 10, 64)
+ if err != nil {
+ return 0, err
+ }
+ if int64(n) < 0 || int64(int(n)) != int64(n) {
+ // Int overflow.
+ return maxN, nil
+ }
+ ni := int(n)
+ if ni > maxN {
+ return maxN, nil
+ }
+ return ni, nil
+}
diff --git a/lib/memory/memory_linux_test.go b/lib/memory/memory_linux_test.go
new file mode 100644
index 0000000000..b74bb98589
--- /dev/null
+++ b/lib/memory/memory_linux_test.go
@@ -0,0 +1,19 @@
+package memory
+
+import (
+ "testing"
+)
+
+func TestReadLXCMemoryLimit(t *testing.T) {
+ const maxMem = 1<<31 - 1
+ n, err := readLXCMemoryLimit(maxMem)
+ if err != nil {
+ t.Fatalf("unexpected error in readLXCMemoryLimit: %s", err)
+ }
+ if n < 0 {
+ t.Fatalf("n must be positive; got %d", n)
+ }
+ if n > maxMem {
+ t.Fatalf("n must be smaller than maxMem=%d; got %d", maxMem, n)
+ }
+}