Master Linux Kernel, Nginx, MySQL & Tomcat Tuning for High‑Performance Servers

1. Linux kernel parameters

Common parameters for /etc/sysctl.conf:

net.core.netdev_max_backlog = 32768    # maximum packets queued
net.core.rmem_max = 8388608           # socket read buffer size
net.core.wmem_max = 8388608           # socket write buffer size
net.core.somaxconn = 32768            # max listen queue length per port
net.ipv4.ip_local_port_range = 1024 65000   # allowed port range
net.ipv4.tcp_fin_timeout = 30        # TIME_WAIT to CLOSED wait time
net.ipv4.tcp_keepalive_time = 1200   # keepalive interval
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_synack_retries = 2
net.ipv4.tcp_syn_retries = 2
net.ipv4.tcp_synack_retries = 1      # SYN+ACK retries before giving up
net.ipv4.tcp_syn_retries = 1          # SYN retries before giving up
net.ipv4.tcp_max_tw_buckets = 6000   # max TIME_WAIT sockets
net.ipv4.tcp_tw_recycle = 1          # fast recycle of TIME_WAIT sockets (default 0)
net.ipv4.tcp_tw_reuse = 1            # allow reuse of TIME_WAIT sockets (default 0)
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_max_orphans = 3276800
net.ipv4.tcp_max_syn_backlog = 65536 # SYN queue length
fs.file-max = 65535                  # max open files system-wide
fs.nr_open = 65535                   # must be >= fs.file-max

Apply changes: sysctl -p Adjust /etc/security/limits.conf to raise file descriptor limits:

* soft nofile 65535
* hard nofile 65535

Verify with:

ulimit -a

2. Nginx main tuning parameters

Worker and connection settings (place in nginx.conf):

worker_processes 8;                 # match CPU cores
worker_rlimit_nofile 65535;         # max file descriptors per worker
use epoll;                          # epoll event model
worker_connections 102400;         # max connections per worker

keepalive_timeout 60;               # keepalive timeout
client_body_buffer_size 64K;
client_header_buffer_size 8k;
large_client_header_buffers 4 128k;
client_max_body_size 8m;
open_file_cache max=204800 inactive=30s;
open_file_cache_valid 30s;
open_file_cache_min_uses 1;

3. MySQL configuration (example for an 8 GB server)

[mysqld]
port = 3306
socket = /var/lib/mysql/mysql.sock
user = mysql
default_storage_engine = InnoDB
skip_name_resolve
key_buffer_size = 32M
myisam_recover = FORCE,BACKUP
max_allowed_packet = 16M
max_connect_errors = 1000000
log_bin = /var/lib/mysql/mysql-bin
expire_logs_days = 7
sync_binlog = 0
tmp_table_size = 32M
max_heap_table_size = 32M
query_cache_type = 1
query_cache_size = 32M
max_connections = 500
thread_cache_size = 50
open_files_limit = 65535
table_definition_cache = 1024
table_open_cache = 2048
innodb_flush_method = O_DIRECT
innodb_log_files_in_group = 2
innodb_log_file_size = 256M
innodb_flush_log_at_trx_commit = 2
innodb_file_per_table = 1
innodb_buffer_pool_size = 4G
log_error = /var/log/mysql-error.log
log_queries_not_using_indexes = 1
slow_query_log = 1
slow_query_log_file = /var/log/mysql-slow.log

4. Tomcat connector tuning

In server.xml under the Connector for port 8080, add:

connectionTimeout="20000"
processorCache="1000"
acceptCount="5000"
acceptorThreadCount="8"   # match CPU cores
maxThreads="2000"
minSpareThreads="100"
socket.appReadBufSize="1024"
socket.appWriteBufSize="1024"
socket.bufferPool="1000"

Adjust JVM options in catalina.sh (example):

JAVA_OPTS="-server -Xms1048m -Xmx3072m -Xss1024K -XX:PermSize=64m -XX:MaxPermSize=128m -XX:NewRatio=4"

5. Hardware load monitoring commands

top               # CPU usage
free -m           # memory usage
iostat -kx 2      # disk I/O
sar -n DEV 2      # network traffic

Reference: Nginx optimization for over 100k concurrent connections.