Linux高并发场景下的网络参数调优实战指南

vCPU: 8核 | 内存: 16GB | 网络带宽: 4Gbps | PPS: 80万

net.core.somaxconn = 65535
net.ipv4.tcp_max_syn_backlog = 8192
net.ipv4.tcp_max_tw_buckets = 131072
net.ipv4.ip_local_port_range = 1024 61999

watch -n 1 'netstat -ant | awk '\''/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'\'''

ESTABLISHED 790
TIME_WAIT 2464
SYN_RECV 32  # 半连接重点关注！

# 查看SYN_RECV连接详情
ss -ntp state syn-recv
# 监控队列溢出
netstat -s | grep -i 'listen drops'

echo "net.ipv4.tcp_tw_reuse = 1" >> /etc/sysctl.conf
echo "net.ipv4.tcp_max_tw_buckets = 262144" >> /etc/sysctl.conf
echo "net.ipv4.ip_local_port_range = 1024 65000" >> /etc/sysctl.conf

echo "net.ipv4.tcp_fin_timeout = 30" >> /etc/sysctl.conf

echo "net.ipv4.tcp_max_syn_backlog = 65535" >> /etc/sysctl.conf
echo "net.core.somaxconn = 65535" >> /etc/sysctl.conf
echo "net.core.netdev_max_backlog = 10000" >> /etc/sysctl.conf

cat >> /etc/sysctl.conf <<EOF
net.ipv4.tcp_mem = 8388608 12582912 16777216
net.ipv4.tcp_rmem = 4096 87380 16777216
net.ipv4.tcp_wmem = 4096 65536 16777216
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
EOF

echo "net.ipv4.tcp_keepalive_time = 600" >> /etc/sysctl.conf
echo "net.ipv4.tcp_keepalive_intvl = 30" >> /etc/sysctl.conf

#!/bin/bash
while true; do
  clear
  date
  echo "---- TCP状态 ----"
  netstat -ant | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'
  echo "---- 半连接队列 ----"
  ss -ltn | awk 'NR>1 {print "Listen队列: Recv-Q="$2", Send-Q="$3}'
  echo "---- 端口使用率 ----"
  echo "已用端口: $(netstat -ant | grep -v LISTEN | awk '{print $4}' | cut -d: -f2 | sort -u | wc -l)/$((65000-1024))"
  sleep 5
done

alert: TCP_SYN_Dropped
expr: increase(node_netstat_Tcp_Ext_SyncookiesFailed{job="node"}[1m]) > 0
for: 5m
labels:
  severity: critical
annotations:
  summary: "SYN队列溢出 (实例 {{ $labels.instance }})"

wrk -t16 -c10000 -d60s http://service:8080

# 计算安全值（单位：页，1页=4KB）
echo $(( $(free -m | awk '/Mem:/ {print $2}') * 1024 / 4 / 3 )) >> /proc/sys/net/ipv4/tcp_mem

listen 80 backlog=65535;