我有一堆服务器。它们是裸机和虚拟机的混合体。全部运行 Ubuntu Bionic。这两种类型的服务器都存在此问题。
仅供参考，我读过类似的问题，也读过答案。我相信这是一个独特的问题。
我是这里的 Infra 人员，我已经想不出主意了。我找不到使用 RAM 的东西。一旦情况变得危急，就会引发 OOM。服务器不使用 Swap。
# free -h
total used free shared buff/cache available
Mem: 7.7G 7.2G 205M 9.9M 369M 499M
Swap: 0B 0B 0B
# cat /proc/meminfo
MemTotal: 8126308 kB
MemFree: 183608 kB
MemAvailable: 497976 kB
Buffers: 30536 kB
Cached: 263980 kB
SwapCached: 0 kB
Active: 1470404 kB
Inactive: 111476 kB
Active(anon): 1285424 kB
Inactive(anon): 8952 kB
Active(file): 184980 kB
Inactive(file): 102524 kB
Unevictable: 4 kB
Mlocked: 0 kB
SwapTotal: 0 kB
SwapFree: 0 kB
Dirty: 160 kB
Writeback: 0 kB
AnonPages: 1287448 kB
Mapped: 142868 kB
Shmem: 10168 kB
Slab: 279184 kB
SReclaimable: 95864 kB
SUnreclaim: 183320 kB
KernelStack: 11648 kB
PageTables: 18184 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 4063152 kB
Committed_AS: 4175792 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 0 kB
VmallocChunk: 0 kB
HardwareCorrupted: 0 kB
AnonHugePages: 0 kB
ShmemHugePages: 0 kB
ShmemPmdMapped: 0 kB
CmaTotal: 0 kB
CmaFree: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 7810548 kB
DirectMap2M: 536576 kB
DirectMap1G: 0 kB
# top
top - 16:23:00 up 185 days, 20:54, 1 user, load average: 0.26, 0.36, 0.43
Tasks: 239 total, 1 running, 144 sleeping, 0 stopped, 1 zombie
%Cpu(s): 1.6 us, 4.0 sy, 0.0 ni, 93.4 id, 0.0 wa, 0.0 hi, 1.1 si, 0.0 st
KiB Mem : 8126308 total, 168140 free, 7534988 used, 423180 buff/cache
KiB Swap: 0 total, 0 free, 0 used. 516260 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
16846 freerad 20 0 903852 417960 5392 S 0.0 5.1 14:21.93 freeradius
16864 bind 20 0 927648 242732 2512 S 0.7 3.0 42:38.28 named
29219 tunnelmon 20 0 3869952 107172 23700 S 0.0 1.3 25:58.11 tunnelmonitor.py
16859 scrambl+ 20 0 110416 58644 2404 S 0.0 0.7 0:02.08 obfsproxy
26697 root 20 0 3933520 43580 2548 S 0.0 0.5 82:43.79 dockerd
19858 timesca+ 20 0 305048 33032 8312 S 0.0 0.4 0:58.58 node
16865 stunnel 20 0 4209416 30900 3092 S 1.7 0.4 26:42.16 stunnel4
11899 diamond 20 0 86376 26956 3216 S 0.0 0.3 0:00.00 diamond
16842 diamond 20 0 86376 26828 3088 S 0.0 0.3 2:03.70 diamond
3244 root 20 0 1865764 25932 572 S 0.0 0.3 581:23.11 containerd
16144 browser+ 20 0 795684 25316 2128 S 2.7 0.3 11:23.89 httpproxy
17278 fpsync 20 0 94484 24516 2324 S 0.0 0.3 0:03.22 gunicorn
18243 diamond 20 0 83908 23584 2412 S 0.0 0.3 0:12.34 diamond
18369 diamond 20 0 83908 23484 2384 S 0.0 0.3 0:35.92 diamond
18280 diamond 20 0 83908 23392 2388 S 0.0 0.3 0:25.64 diamond
17558 diamond 20 0 83776 23176 2344 S 0.0 0.3 0:12.33 diamond
18328 diamond 20 0 83908 23148 2140 S 0.0 0.3 0:07.82 diamond
18150 diamond 20 0 83520 23032 2224 S 0.0 0.3 0:14.70 diamond
17523 diamond 20 0 83388 22668 2160 S 0.0 0.3 0:08.29 diamond
18117 diamond 20 0 83520 22620 1896 S 0.0 0.3 0:13.21 diamond
18208 diamond 20 0 83776 22612 1764 S 0.0 0.3 0:01.44 diamond
17405 diamond 20 0 83132 22032 1624 S 0.0 0.3 1:12.88 diamond
17541 diamond 20 0 83528 21604 1000 S 0.0 0.3 0:41.34 diamond
17576 diamond 20 0 83520 21556 900 S 0.0 0.3 0:30.24 diamond
23418 strongs+ 20 0 68596 21324 8268 S 3.3 0.3 0:00.10 python3
16638 root 20 0 69176 21112 2404 S 0.0 0.3 11:32.82 supervisord
22541 root 19 -1 102988 20940 12004 S 0.3 0.3 8:22.35 systemd-journal
17484 strongs+ 20 0 1632772 17592 4712 S 0.3 0.2 48:52.86 charon
19628 telegraf 20 0 5037948 16768 4 S 0.0 0.2 3:25.14 telegraf
16843 fpsync 20 0 59092 15752 1676 S 0.0 0.2 0:30.13 gunicorn
19977 obfs4pr+ 20 0 66352 14932 5496 S 0.0 0.2 0:00.11 python3
16851 openvpn 20 0 46312 14352 3264 S 24.6 0.2 166:22.47 openvpn
16848 openvpn 20 0 44864 13036 3300 S 1.3 0.2 175:15.40 openvpn
17028 diamond 20 0 1090552 12604 0 S 0.0 0.2 1:56.94 diamond
16850 openvpn 20 0 43948 12160 3348 S 5.0 0.1 167:30.49 openvpn
6754 root 20 0 169264 10304 8764 S 0.0 0.1 0:00.02 sshd
21308 root 20 0 139148 9616 228 S 0.0 0.1 0:13.55 fail2ban-server
16840 openvpn 20 0 180084 9304 3380 S 0.0 0.1 0:07.93 openvpn-api-gra
16847 openvpn 20 0 40764 9208 3572 S 1.0 0.1 58:54.04 openvpn
7008 root 20 0 161708 8792 7360 S 0.0 0.1 0:00.68 sudo
30989 syslog 20 0 299448 6288 3152 S 0.3 0.1 2:42.85 rsyslogd
19979 obfs4pr+ 20 0 1497424 5712 0 S 1.0 0.1 10:05.53 obfs4proxy
1 root 20 0 226484 5640 2024 S 0.0 0.1 396:39.45 systemd
6757 tbear 20 0 76756 5556 4360 S 0.0 0.1 0:00.15 systemd
19816 root 20 0 1670468 4244 1548 S 0.0 0.1 0:19.03 docker-proxy
2662 message+ 20 0 53680 4180 0 S 0.0 0.1 114:04.87 dbus-daemon
7015 root 20 0 21612 4028 3452 S 0.0 0.0 0:00.16 bash
22288 root 20 0 39828 3876 3096 R 0.3 0.0 0:00.22 top
# uname -r
4.15.0-66-generic
我也检查了一下slabtop，发现用处不大。另外，从中可以看出/proc/meminfo。我还尝试了不同的方法，例如使用ps_mem来跟踪内存使用情况。我已经没有主意了。如果有人有任何想法，我将不胜感激。谢谢注意：重新启动可以暂时解决问题，但这不是一个实用的解决方案。
答案1
如果你运行以下命令，你的系统是否会感觉更好：
#memory before
free -h
#clear pagecache, dentries, inode
sync
echo 3 > /proc/sys/vm/drop_caches
#memory after
free -h
如果情况良好并且您有更多的可用内存，您可以考虑将此命令添加到每日 CRON JOB 中：此处提供了此命令的每日 CRON 示例