check-connection-pool

Connection Pool Performance Analysis

Analyze PHP code for connection pool issues and database connection management problems.

When to Use

• Reviewing database-heavy PHP applications
• Investigating connection exhaustion or memory leaks
• Auditing long-running workers (queue consumers, daemons)
• Checking Doctrine EntityManager lifecycle issues
• Reviewing HTTP client usage patterns

Analysis Approach

1. Scan for connection creation patterns (PDO, Redis, Guzzle)
2. Check loop bodies for repeated connection instantiation
3. Verify try/finally cleanup on pool acquire/release
4. Check timeout configuration on all connection types
5. Review persistent connection usage and state reset
6. Audit worker processes for connection refresh logic

Detection Rules

ID	Pattern	What to Look For
CP-01	Connection leak	new PDO without cleanup in exception/early-return paths
CP-02	Connection in loop	new PDO/new Redis/new Client inside foreach/while
CP-03	Missing timeout	PDO without ATTR_TIMEOUT, Redis without connect timeout
CP-04	Persistent misuse	ATTR_PERSISTENT => true without shutdown cleanup
CP-05	Pool exhaustion	Multiple connections opened without reuse
CP-06	Missing finally	$pool->release() not in finally block
CP-07	State not reset	Connection returned to pool with modified session state
CP-08	Doctrine issues	EntityManager not cleared, long-held transactions
CP-09	Worker stale conn	Long-running worker without connection refresh
CP-10	HTTP no pooling	file_get_contents in loop, no keep-alive headers

Grep Patterns

# New connection in loops
Grep: "foreach.*\{[^}]*new PDO|while.*\{[^}]*new PDO" --glob "**/*.php" --multiline

# Missing connection close
Grep: "new Redis\(\)" --glob "**/*.php"

# Persistent connections
Grep: "ATTR_PERSISTENT" --glob "**/*.php"

# Connection without timeout
Grep: "new PDO\s*\([^)]+\)\s*;" --glob "**/*.php"

# Static connection storage
Grep: "static.*PDO|static.*connection" --glob "**/*.php"

Severity Classification

Pattern	Severity
Connection in loop	Critical
Connection leak (no finally)	Critical
No connection timeout	Major
Pool exhaustion risk	Major
Missing connection health check	Major
Persistent connection misuse	Minor
Static connection storage	Minor

Output Format

### Connection Pool: [Description]

**Severity:** Critical/Major/Minor
**Location:** `file.php:line`
**Impact:** [Database overload, connection exhaustion, memory leak]

**Issue:**
[Description of the connection management problem]

**Code:**
[Problematic code snippet]

**Fix:**
[Proper connection management code]

**Expected Improvement:**
- Connection count: 100 -> 10 (pooled)
- Memory usage: -50% (connections reused)
- DB load: -80% (connection overhead eliminated)

References

• references/patterns.md — detailed detection patterns with code examples, secure pool implementations, health check and worker refresh patterns