Production checklist

Note that the advice on this page is not always applicable for every use case and thus should be applied with caution. Do not apply the changes you really do not need.

You may want to consider the following options before putting your Armeria application into production.

Specify the maximum number of accepted connections. The default is unbounded.

import com.linecorp.armeria.server.Server;
import com.linecorp.armeria.server.ServerBuilder;

ServerBuilder sb = Server.builder();
sb.maxNumConnections(500);

Specify an alternative blockingTaskExecutor based on expected workload if your server has a service that uses it, such as TomcatService, JettyService and THttpService with synchronous service implementation. The default is a simple ScheduledThreadPoolExecutor with maximum 200 threads, provided by CommonPools.
```
import com.linecorp.armeria.server.ServerBuilder;

ServerBuilder sb = Server.builder();
sb.blockingTaskExecutor(myScheduledExecutorService);
```

Specify the default limits of an HTTP request or response.

import java.time.Duration;
import com.linecorp.armeria.client.ClientBuilder;
import com.linecorp.armeria.server.ServerBuilder;

// Server-side
ServerBuilder sb = Server.builder();
sb.maxRequestLength(1048576); // bytes (default: 10 MiB)
sb.requestTimeout(Duration.ofSeconds(7)); // (default: 10 seconds)

// Client-side
ClientBuilder cb = Clients.builder(...); // or WebClient.builder(...)
cb.maxResponseLength(1048576); // bytes (default: 10 MiB)
cb.responseTimeout(Duration.ofSeconds(10)); // (default: 15 seconds)

Decorate your services with ThrottlingService which lets you fail the incoming requests based on a policy, such as 'fail if the rate of requests exceed a certain threshold.

import com.linecorp.armeria.server.throttling.ThrottlingService;
import com.linecorp.armeria.server.throttling.ThrottlingStrategy;

ServerBuilder sb = Server.builder();
sb.service("/my_service", // Allow up to 1000 requests/sec.
           myService.decorate(ThrottlingService.newDecorator(
                   ThrottlingStrategy.rateLimiting(1000.0))));

Decorate your clients with RetryingClient. See Automatic retry.
Decorate your clients with CircuitBreakerClient. See Circuit breaker.

You can use Armeria's CircuitBreaker API for non-Armeria clients without circuit breaker support. See Using CircuitBreaker with non-Armeria client.

Tune the socket options.

import com.linecorp.armeria.client.ClientBuilder;
import com.linecorp.armeria.client.ClientFactory;
import com.linecorp.armeria.client.ClientFactoryBuilder;
import com.linecorp.armeria.server.ServerBuilder;
import io.netty.channel.ChannelOption;

// Server-side
ServerBuilder sb = Server.builder();
sb.channelOption(ChannelOption.SO_BACKLOG, ...);
sb.channelOption(ChannelOption.SO_REUSEADDR, ...);
sb.childChannelOption(ChannelOption.SO_SNDBUF, ...);
sb.childChannelOption(ChannelOption.SO_RCVBUF, ...);

// Client-side
ClientFactoryBuilder cfb = ClientFactory.builder();
cfb.channelOption(ChannelOption.SO_REUSEADDR, ...);
cfb.channelOption(ChannelOption.SO_SNDBUF, ...);
cfb.channelOption(ChannelOption.SO_RCVBUF, ...);
ClientFactory cf = cfb.build();
ClientBuilder cb = Clients.builder(...);
cb.factory(cf);

Consider increasing ClientFactoryBuilder.maxNumEventLoopsPerEndpoint() and ClientFactoryBuilder.maxNumEventLoopsPerHttp1Endpoint() when a client needs to send a large number of requests to a specific endpoint. The client will assign more CPU resources and create more connections by increasing the number of event loops up to the quantity in ClientFactory.eventLoopGroup().

import com.linecorp.armeria.client.Clients;
import com.linecorp.armeria.client.ClientBuilder;
import com.linecorp.armeria.client.ClientFactory;
import com.linecorp.armeria.client.ClientFactoryBuilder;

ClientFactoryBuilder cfb = ClientFactory.builder();
cfb.maxNumEventLoopsPerEndpoint(16); // default: 1
cfb.maxNumEventLoopsPerHttp1Endpoint(16); // default: 1
ClientFactory cf = cfb.build();
ClientBuilder cb = Clients.builder(...);
cb.factory(cf);