Fine-Tuning Tomcat 8 JDBC Connection Pool

🔧 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"

📎 Tomcat 8 Docs - maxActive

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⏱ 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"

📎 Tomcat 8 Docs - maxWait

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✅ 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

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💤 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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