Production usage

Get your NRedisStack app ready for production

This guide offers recommendations to get the best reliability and performance in your production environment.

Checklist

Each item in the checklist below links to the section for a recommendation. Use the checklist icons to record your progress in implementing the recommendations.

Recommendations

The sections below offer recommendations for your production environment. Some of them may not apply to your particular use case.

Event handling

The ConnectionMultiplexer class publishes several different types of events for situations such as configuration changes and connection failures. Use these events to record server activity in a log, which you can then use to monitor performance and diagnose problems when they occur. See the StackExchange.Redis Events page for the full list of events.

Server notification events

Some servers (such as Azure Cache for Redis) send notification events shortly before scheduled maintenance is due to happen. You can use code like the following to respond to these events (see the StackExchange.Redis docs for the full list of supported events). For example, you could inform users who try to connect that service is temporarily unavailable rather than letting them run into errors.

using NRedisStack;
using StackExchange.Redis;

ConnectionMultiplexer muxer = ConnectionMultiplexer.Connect("localhost:6379");

muxer.ServerMaintenanceEvent += (object sender, ServerMaintenanceEvent e) => {
    // Identify the event and respond to it here.
    Console.WriteLine($"Maintenance event: {e.RawMessage}");
};

Timeouts

If a network or server error occurs while your code is opening a connection or issuing a command, it can end up hanging indefinitely. To prevent this, NRedisStack sets timeouts for socket reads and writes and for opening connections.

By default, the timeout is five seconds for all operations, but you can set the time (in milliseconds) separately for connections and commands using the ConnectTimeout, SyncTimeout, and AsyncTimeout configuration options:

var muxer = ConnectionMultiplexer.Connect(new ConfigurationOptions {
    ConnectTimeout = 1000,  // 1 second timeout for connections.
    SyncTimeout = 2000,     // 2 seconds for synchronous commands.
    AsyncTimeout = 3000     // 3 seconds for asynchronous commands.
        .
        .
});

var db = muxer.GetDatabase();

The default timeouts are a good starting point, but you may be able to improve performance by adjusting the values to suit your use case.

Exception handling

Redis handles many errors using return values from commands, but there are also situations where exceptions can be thrown. In production code, you should handle exceptions as they occur. The list below describes some the most common Redis exceptions:

• RedisConnectionException: Thrown when a connection attempt fails.
• RedisTimeoutException: Thrown when a command times out.
• RedisCommandException: Thrown when you issue an invalid command.
• RedisServerException: Thrown when you attempt an invalid operation (for example, trying to access a stream entry using an invalid ID).

Retries

During the initial ConnectionMultiplexer.Connect() call, NRedisStack will keep trying to connect if the first attempt fails. By default, it will make three attempts, but you can configure the number of retries using the ConnectRetry configuration option:

var muxer = ConnectionMultiplexer.Connect(new ConfigurationOptions {
    ConnectRetry = 5,  // Retry up to five times.
        .
        .
});

After the initial Connect() call is successful, NRedisStack will automatically attempt to reconnect if the connection is lost. You can specify a reconnection strategy with the ReconnectRetryPolicy configuration option. NRedisStack provides two built-in classes that implement reconnection strategies:

• ExponentialRetry: (Default) Uses an exponential backoff strategy, where you specify an increment to the delay between successive attempts and, optionally, a maximum delay, both in milliseconds.
• LinearRetry: Uses a linear backoff strategy with a fixed delay between attempts, in milliseconds.

The example below shows how to use the ExponentialRetry class:

var muxer = ConnectionMultiplexer.Connect(new ConfigurationOptions {
    // 500ms increment per attempt, max 2000ms.
    ReconnectRetryPolicy = new ExponentialRetry(500, 2000),  
        .
        .
});

You can also implement your own custom retry policy by creating a class that implements the IReconnectRetryPolicy interface.

NRedisStack doesn't provide an automated retry mechanism for commands, but you can implement your own retry logic in your application code. Use a loop with a try/catch block to catch RedisConnectionException and RedisTimeoutException exceptions and then retry the command after a suitable delay, as shown in the example below:

const int MAX_RETRIES = 3;

for (int i = 0; i < MAX_RETRIES; i++) {
    try {
        string value = db.StringGet("foo");
        break;
    } catch (RedisConnectionException) {
        // Wait before retrying.
        Thread.Sleep(500 * (i + 1));
    } catch (RedisTimeoutException) {
        // Wait before retrying.
        Thread.Sleep(500 * (i + 1));
    }
}