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Limit Server Execution Time

Overview

In this guide, you can learn about the single timeout setting in the Go driver, also known as the client-side operation timeout (CSOT).

When you use the Go driver to perform a server operation, you can also limit the amount of time in which the server can finish the operation. The timeout applies to all steps needed to complete the operation, including server selection, connection checkout, and server-side execution. When the timeout expires, the Go driver raises a timeout exception.

Note

Experimental Feature

The CSOT feature is experimental and might change in future driver releases.

timeoutMS Option

To specify a timeout when connecting to a MongoDB deployment, set the timeoutMS connection option to the timeout length in milliseconds. You can set the timeoutMS option in the following ways:

Calling the SetTimeout() method when specifying options for your Client instance
Setting the timeoutMS parameter in your connection string

The following code examples set a client-level timeout of 200 milliseconds. Select the Client or Connection String tab to see the corresponding code.

opts := options.Client().SetTimeout(200 * time.Millisecond)
client, err := mongo.Connect(opts)

uri := "<connection string>/?timeoutMS=200"
client, err := mongo.Connect(options.Client().ApplyURI(uri))

Note

Retries Under Timeout Specification

If you set a timeout on your Client or in an operation-level Context and the server returns a retryable error, the driver retries the operation as many times as possible before the timeout expires.

Once the timeout expires, the driver returns a timeout error. See the Server manual for more information about retryable reads and retryable writes.

Accepted Timeout Values

The following table describes the timeout behavior corresponding to the accepted values for timeoutMS:

Value	Behavior
Positive integer	Sets the timeout to use for operation completion.
`0`	Specifies that operations never time out.
`null` or unset	Defers the timeout behavior to the following settings: waitQueueTimeoutMS socketTimeoutMS wTimeoutMS maxTimeMS These settings are deprecated and are ignored if you set `timeoutMS`.

If you specify the timeoutMS option, the driver automatically applies the specified timeout to each server operation.

Timeout Inheritance

By default, all operations in your application inherit the Timeout option from Client if you do not set a different timeout on specific operations in the operation's Context.

If you set a timeout on a Context passed into an operation, the driver uses that value for the operation. If you do not specify a Context timeout, the operation Context derives the timeout from the Client instance.

The following table describes how the timeout value is inherited at each level:

Level	Inheritance Description
Operation	Takes the highest precedence and overrides the timeout options that you set at any other level.
Transaction	Takes precedence over the timeout value that you set at the client level.
Client	Applies to all databases, collections, sessions, transactions, and operations within that client that do not otherwise specify a Context timeout.

For more information on overrides and specific options, see the following Overrides section.

Overrides

The Go driver supports various levels of configuration to control the behavior and performance of database operations.

You can specify a timeoutMS option at a more specific level to override the client-level configuration. The table in the preceding section describes the levels at which you can specify a timeout setting. This allows you to customize timeouts based on the needs of individual operations.

The following example shows how to set an operation-level timeout in a Context, which takes priority over the client-level timeout:

opts = options.Client().SetTimeout(200 * time.Millisecond)
client, err = mongo.Connect(opts)
if err != nil {
	log.Fatal(err)
}
coll := client.Database("db").Collection("people")
ctx, cancel := context.WithTimeout(context.TODO(), 300*time.Millisecond)
defer cancel()
_, err = coll.InsertOne(ctx, bson.D{{"name", "Agnes Georgiou"}})

Transactions

When you perform a transaction by using the WithTransaction() method, you can apply a timeout to the transaction operations by setting a timeout within the Context.

The following code demonstrates how to set a Context timeout when calling the WithTransaction() method to perform a transaction:

txnContext, cancel := context.WithTimeout(context.TODO(), 300*time.Millisecond)
defer cancel()
result, err := session.WithTransaction(txnContext, func(ctx context.Context) (string, error) {
	// Perform transaction operations
})

If you do not specify a Context timeout, the driver inherits the timeout value set on the parent Client.

You can also pass Context timeouts to the following session methods:

AbortTransaction()
CommitTransaction()
EndSession()

To learn more about transactions, see the Transactions guide.

Cursors

Cursors offer configurable timeout settings when using the CSOT feature. You can adjust cursor timeouts by passing Contexts that have timeout specifications to Cursor methods.

For operations that create cursors, the timeout setting can either limit the lifetime of the cursor or be applied separately to the original operation and all subsequent calls.

For example, if you pass a Context timeout to the Cursor.Next() method, the timeout applies to each action to fetch a result document. If you pass a Context timeout to the Cursor.All() method, the timeout applies to the entire lifetime of the cursor.

To learn more about cursors, see the Access Data From a Cursor guide.

API Documentation

To learn more about using timeouts with the Go driver, see the following API documentation:

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