Fine-Tuning Tomcat 8 JDBC Connection Pool
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🔧 1. Right-Size maxActive
Description: Maximum number of active connections in the pool.
🛑 Issue: Too low = connection starvation. Too high = DB overload.
✅ Recommendation:
maxActive="100"
⏱ 2. Set a Sensible maxWait
Description: How long (in ms) to wait for a connection before throwing an exception.
🛑 Issue: Low value = frequent timeouts under load.
✅ Recommendation:
maxWait="10000"
✅ 3. Avoid Stale Connections with validationQuery, testOnBorrow, and validationInterval
Description: Checks that a DB connection is valid before returning it to the app.
🛑 Issue: Stale connections lead to failed transactions.
✅ Recommendation:
testOnBorrow="true"
validationQuery="SELECT 1"
validationInterval="30000"
📎 Tomcat 8 Docs - validationQuery & testOnBorrow
💤 4. Manage Idle Connections with minIdle, maxIdle, timeBetweenEvictionRunsMillis, minEvictableIdleTimeMillis
Description: Controls idle connection cleanup to avoid leaks and unnecessary DB usage.
✅ Recommendation:
minIdle="10"
maxIdle="30"
timeBetweenEvictionRunsMillis="30000"
minEvictableIdleTimeMillis="60000"
📎 Tomcat 8 Docs - Idle Connection Settings
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