Authors:
- Yuva Priya Arunkumar, Software Engineering Manager
- Connor O Brien, Software Engineer
Is your application experiencing performance bottlenecks due to too many connections? Are you interested in efficiently managing your MySQL connections? Are you looking to supercharge your performance by reducing latency during concurrent connections?
The Managed Connection Pooling feature in Cloud SQL for MySQL enhances application performance and database connection management allowing you to scale your workloads by optimizing resource utilization and connection latency. Managed Connection Pooling delivers significant performance gains, especially for scaled connections, by absorbing sudden connection spikes without overloading the server.
Why does connection pooling matter for your applications?
Connection pools are typically a cache of connections that can be reused by an application thereby reducing the time it takes to establish a database connection. MySQL typically uses a thread-per-connection model. This means each new client connection is handled by a separate thread within a single server process.
Modern architectures (microservices, serverless functions like Cloud Functions/Cloud Run), frequently create numerous short-lived connections. MySQL’s thread based connection creation makes establishing a new connection efficient. However, efficient resource utilization is still vital to meet scalability requirements to fully unlock the hardware potential.
Typically, MySQL databases have a bell-curve graph of database performance compared to concurrency:
Performance measured in Queries per second (QPS) at different levels of concurrent connections
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Low concurrency: Performance isn’t at peak because database traffic is run too serially.
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Moderate concurrency: Performance improves as the database is able to handle database traffic in parallel across multiple connections.
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High concurrency: Performance degrades as connections spend their time waiting for locks
Therefore one of the key measures of a good connection pooling solution would be the ability to improve database performance when dealing with a large number of concurrent connections.
How It Works
Managed Connection Pooling for Cloud SQL for MySQL improves performance under high concurrency by moving away from the standard one-thread-per-client connection model. Instead, each MySQL connection is assigned to a thread group. Each thread group can contain a pool of threads. The number of active threads within each group is managed by the connection pool.
MySQL instance with Managed Connection pooling enabled
MySQL connections are allocated round-robin to one of max_pool_size thread groups, and new threads are only created if there is no sleeping worker thread that is available to handle the connection. Each thread group has one listener thread responsible for adding events to the thread group’s queue. Concurrently, the thread group wakes up to a defined number of worker threads to handle events from the queue.
As a result of this alternative scheduling model, Managed Connection Pooling for Cloud SQL for MySQL spawns fewer threads than the default one-thread-per-connection model, and reduces the amount of locking contention between active threads.
Key Benefits
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Improved Performance: Reusing existing connections minimizes latency associated with creating new connections and leads to faster response times for applications.
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Scalability: The connection pool allows applications to handle a larger number of concurrent requests without overwhelming the database by spawning new threads.
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Resource Optimization: Efficiently managing connections reduces resource utilization for both the application and the database server.
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Increased Throughput: Applications handle more requests with the same database resources.
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Operational simplicity: Connection pooling reduces operational overhead without requiring deployment, configuration, and management of a separate pooling proxy.
Is Connection pooling right for me?
Number of Connections
High traffic web applications with many concurrent users can create connection surge during peak times. This can overwhelm applications, leading to deteriorated performance or even result in application crashes. Managed connection pooling helps maintain strong performance even with a large number of client connections by reducing the amount of context switching and hot lock contentions. This enables Cloud SQL instances to scale up to a significantly higher number of connections with Managed Connection Pooling. However, managed connection pooling does not offer notable performance benefits when the MySQL instance has fewer than 1000 connections.
Type of workload
Connection pooling can significantly increase throughput for read-heavy workloads, particularly for larger instances. Imagine a bustling e-commerce site during a flash sale with many concurrent reads on product deals, monitoring systems collecting large amounts of real time data, financial institutions providing real time market data. All of these queries are typically short, very frequent, and highly concurrent which can benefit from connection pooling. While the gains are most dramatic for reads, connection pooling can still offer subtle benefits for write-intensive workloads.
Connection span
Many applications can create workloads characterized by a large number of short CPU-bound queries. OLTP (Online Transaction Processing) workloads with many short, frequent queries are such cases where connection Pooling is more effective. Scenarios involving a smaller number of long running connections, say complex analytical queries which take several hours to complete might not see noticeable gains from connection pooling.
Get Started Today
To take advantage of Managed Connection pooling for your CloudSQL MySQL application and understand prerequisites, configuration options, key monitoring metrics refer to -https://cloud.google.com/sql/docs/mysql/managed-connection-pooling