How to Monitor Database Connection Pool Usage on Linux Server
Step-by-step guide to monitor database connection pool usage. Track connection count, detect pool exhaustion, and optimize connection management.
How to Monitor Database Connection Pool Usage on Linux Server
Monitor database connection pool usage to track connection count, detect pool exhaustion, and optimize connection management. This guide shows you how to monitor connection pools and set up automated monitoring.
For comprehensive database monitoring, see Database Performance Monitoring. For troubleshooting connection issues, see Database Connection Timeout Errors.
Why Monitoring Connection Pools Matters
Connection pool exhaustion can cause application failures and poor performance. Monitoring connection pool usage helps prevent pool exhaustion and ensures optimal database performance.
Method 1: Monitor MySQL Connection Pool
Check Connection Count
# Count active connections
mysql -u root -p -e "SELECT count(*) FROM information_schema.processlist;"
# Check current vs max connections
mysql -u root -p -e "SELECT
(SELECT count(*) FROM information_schema.processlist) as current_connections,
(SELECT @@max_connections) as max_connections,
ROUND((SELECT count(*) FROM information_schema.processlist) / (SELECT @@max_connections) * 100, 2) as usage_percent;"
# View connection details
mysql -u root -p -e "SELECT id, user, host, db, command, time, state FROM information_schema.processlist;"
Method 2: Monitor PostgreSQL Connection Pool
Check Connection Count
# Count active connections
psql -U postgres -c "SELECT count(*) FROM pg_stat_activity;"
# Check current vs max connections
psql -U postgres -c "SELECT
count(*) as current_connections,
(SELECT setting::int FROM pg_settings WHERE name = 'max_connections') as max_connections,
ROUND(count(*)::float / (SELECT setting::int FROM pg_settings WHERE name = 'max_connections')::float * 100, 2) as usage_percent
FROM pg_stat_activity;"
# View connection details
psql -U postgres -c "SELECT pid, usename, datname, state, client_addr FROM pg_stat_activity;"
Method 3: Automated Connection Pool Monitoring with Zuzia.app
Set up automated monitoring to track connection pool usage continuously and receive alerts when pool usage exceeds thresholds.
Step 1: Add Connection Pool Monitoring Command
-
Log in to Zuzia.app Dashboard
- Access your Zuzia.app account
- Navigate to your server
- Click "Add Scheduled Task"
-
Configure Connection Pool Check Command
# MySQL mysql -u root -pPASSWORD -e "SELECT count(*) FROM information_schema.processlist;" # PostgreSQL psql -U postgres -c "SELECT count(*) FROM pg_stat_activity;"- Set execution frequency (every 5-10 minutes)
- Configure alerts when pool usage exceeds thresholds
Step 2: Configure Alert Thresholds
- Warning: Pool usage > 70% of max_connections
- Critical: Pool usage > 85% of max_connections
- Emergency: Pool usage > 95% of max_connections
Step 3: Monitor Connection Details
Add command to check connection states:
# MySQL: Check connection states
mysql -u root -p -e "SELECT state, count(*) FROM information_schema.processlist GROUP BY state;"
# PostgreSQL: Check connection states
psql -U postgres -c "SELECT state, count(*) FROM pg_stat_activity GROUP BY state;"
Best Practices for Connection Pool Monitoring
1. Monitor Pool Usage Continuously
- Track connection count regularly
- Alert when pool usage exceeds thresholds
- Monitor connection trends over time
- Plan capacity upgrades based on data
2. Monitor Connection States
- Track active vs idle connections
- Identify connection leaks
- Monitor long-running connections
- Optimize connection usage
3. Set Appropriate Pool Limits
- Configure max_connections based on server resources
- Monitor connection usage vs limits
- Adjust limits based on actual usage
- Plan upgrades before limits are reached
4. Optimize Connection Usage
- Implement connection pooling
- Close connections properly
- Monitor connection leaks
- Optimize application connection usage
Troubleshooting Connection Pool Issues
Step 1: Identify Pool Problems
When connection pool is exhausted:
# Check current connection count
mysql -u root -p -e "SELECT count(*) FROM information_schema.processlist;"
psql -U postgres -c "SELECT count(*) FROM pg_stat_activity;"
# Check max connections
mysql -u root -p -e "SHOW VARIABLES LIKE 'max_connections';"
psql -U postgres -c "SHOW max_connections;"
Step 2: Resolve Pool Issues
Based on investigation:
-
Kill Idle Connections:
# MySQL: Kill idle connections mysql -u root -p -e "KILL <process_id>;" # PostgreSQL: Kill idle connections psql -U postgres -c "SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE state = 'idle';" -
Increase Pool Limits:
# MySQL: Increase max connections mysql -u root -p -e "SET GLOBAL max_connections = 500;" # PostgreSQL: Edit postgresql.conf # max_connections = 500 -
Fix Connection Leaks:
- Review application code
- Fix unclosed connections
- Implement connection pooling
FAQ: Common Questions About Connection Pool Monitoring
How often should I check connection pool usage?
For production databases, continuous automated monitoring is essential. Zuzia.app can check connection pool usage every few minutes, alerting you when pool usage exceeds thresholds.
What is considered high connection pool usage?
High connection pool usage depends on your max_connections setting. Generally, usage above 70-80% of max_connections indicates potential issues and should be investigated.
How do I prevent connection pool exhaustion?
Prevent connection pool exhaustion by monitoring pool usage continuously, implementing connection pooling, fixing connection leaks, optimizing connection usage, and scaling database infrastructure if needed.
Can connection pool monitoring impact database performance?
Connection pool monitoring commands have minimal impact on database performance when done correctly. Use appropriate monitoring frequency and avoid monitoring during peak database usage periods.
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