Connection pooling

As explained in Go by Example

A connection pool is a managed collection of reusable network connections maintained to avoid repeatedly establishing new connections.

Connection pooling keeps reusable network connections under a long-lived manager instead of establishing a new connection for every operation. Reuse avoids the network latency and handshakes of reconnecting, while the manager selects, opens, and closes connections as needed. section 10.1 section 10.1.2

In Go’s database/sql API, sql.Open verifies a registered driver and returns a *sql.DB whose pool may initially be empty. Calling PingContext verifies connectivity and, on success, adds the first connection; retain the resulting *DB for the program lifetime rather than reopening it per query. section 10.1.2

Open and verify a SQLite pool

Use sql.Open("sqlite", dsn) to create the *sql.DB handle, then call db.PingContext(ctx). Wrap either failure with context such as "opening" or "pinging" before returning the handle for later queries. section 10.1.2

A pool tracks idle and in-use connections. For a database task, it uses an idle connection when available; otherwise it establishes one. Tune capacity with SetMaxOpenConns and SetMaxIdleConns, and bound reuse with SetConnMaxLifetime and SetConnMaxIdleTime. section 10.1.2

The same reuse principle applies to HTTP: http.Transport is a RoundTripper with a TCP connection pool. Reuse one Transport while sending requests, whether it is the default transport or a selected implementation behind http.Client. section 7.4.1

Figure 10.2 Connecting to the SQLite database using Open and PingContext

Trace the transition from an empty *sql.DB pool after Open to its first reusable connection after PingContext succeeds. section 10.1.2

How Go by Example covers it

How deep it goes

Explains pool initialization, selection, lifecycle retention, and four database tuning controls without detailing their numeric trade-offs.

Examples

Demonstrates a SQLite Dial function using sql.Open and PingContext, plus HTTP requests sharing an http.Transport.

What it assumes

Assumes familiarity with Go database and HTTP APIs while introducing driver verification and connection establishment steps.

What you can do after

Apply it via *sql.DB and http.Transport by retaining shared handles and optionally configuring database pool limits.

How it connects

Connects connection pooling to database/sql, drivers, PingContext, HTTP clients, RoundTripper, and http.Transport.

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Also explained in

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  Python Concurrency with asyncioConnection pooling is the practice of maintaining reusable network connections so multiple operations can share them.
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  .NET in Action, Second EditionA connection pool is a managed collection of reusable network connections that limits and coordinates simultaneous access.
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  Rust Servers, Services, and AppsA connection pool is a managed collection of reusable database connections shared among clients or execution threads.
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  Logs and TelemetryConnection pooling is the practice of maintaining reusable database connections so operations can execute without repeatedly establishing new connections.
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  Elixir in Action, Third EditionA database connection pool is a bounded collection of reusable database connections managed to constrain simultaneous database operations.
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  PostgreSQL Mistakes and How to Avoid ThemConnection pooling is a technique that reuses a bounded set of database connections to serve a larger number of client requests.
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  100 Go Mistakes and How to Avoid ThemA database connection pool is a managed collection of reusable database connections that are allocated to operations and returned for later use.
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  ASP.NET Core in Action, 3eConnection pooling is the reuse of established network connections across multiple client requests to reduce connection-setup overhead.

Compare how 9 books explain connection pooling →

Related concepts

• database connectionuses · A database connection is an active communication channel or session through which software sends operations to and receives results from a database system.
• connection poolerimplemented by · A connection pooler is software that maintains reusable database connections and assigns them to application requests as needed.

This explainer was generated by Manning's knowledge graph from the text of Go by Example. The section links point to the parts of the book it draws on.