Why does MariaDB's CPU utilization exceed 100%?

MariaDB's CPU utilization can exceed 100% due to several reasons, primarily related to high query loads, inefficient queries, or system resource constraints. Since modern CPUs have multiple cores, Linux systems often report CPU utilization as a percentage of the total available cores. For example, if a server has 8 CPU cores, 100% utilization means all 8 cores are fully used, and 800% would mean all cores are maxed out.

Common causes include:

1. High query volume: A sudden spike in database queries (e.g., from an application or automated scripts) can overwhelm the CPU.
2. Inefficient queries: Poorly optimized queries (e.g., missing indexes, full table scans) consume excessive CPU cycles.
3. Lock contention: Long-running transactions or locks on tables can cause other queries to wait, increasing CPU load.
4. Insufficient resources: If the server has too few CPU cores or insufficient RAM, MariaDB may rely more on CPU for disk I/O operations.

Example:
If a MariaDB server with 4 cores shows 400% CPU utilization, it means all 4 cores are fully utilized. This could happen if a complex JOIN query without proper indexes is executed repeatedly by an application.

Solution:

• Optimize queries using EXPLAIN to identify bottlenecks.
• Add missing indexes to speed up query execution.
• Scale vertically (upgrade CPU/RAM) or horizontally (use read replicas).
• Use connection pooling to reduce connection overhead.

For high-performance database workloads, Tencent Cloud's TDSQL for MySQL (compatible with MariaDB) provides auto-scaling, query optimization, and monitoring tools to manage CPU utilization effectively.