Performance Tuning

JVM Memory

Set heap sizes in bin/setenv.sh (create it if missing):

JAVA_OPTS="-Xms1g -Xmx2g -XX:MaxMetaspaceSize=512m -XX:+UseG1GC"
export JAVA_OPTS

Do not set Xmx higher than free RAM; the JVM and the OS need headroom. Tune with -Xss1m only if you see StackOverflowError.

Connector Threads

<Connector port="8080" protocol="HTTP/1.1" maxThreads="200"
           minSpareThreads="25" acceptCount="100" connectionTimeout="20000"/>

• maxThreads - do not set blindly high; each thread costs memory. 200 is a sane start.
• acceptCount - how many connections queue before refusing.
• Blocking DB calls per thread: pool accordingly, add secondaries for reads.

Compression

<Connector ... compression="on" compressionMinSize="2048"
           compressibleMimeType="text/html,text/xml,text/css,text/javascript,application/json"/>

Gzip/br text output reduces payloads by 60-80%. Enable for JSON and HTML APIs.

Static Content

• Serve static files from a CDN or nginx - Tomcat is a servlet engine, not a static server.
• Set cache headers / far-future-expiry on immutable assets (images, css, js) via filter or nginx.

Warm Up and Monitor

• JIT warm-up: hit the app with synthetic traffic after restart.
• Measure, change one thing, measure again (heap, GC logs, thread usage).

Key Points

• RAM > thread count; profile before raising limits.
• Compression and caching win more than connector tweaks usually.
• Always keep a test: benchmarking before and after.