IBM WebSphere Application Server Performance Cookbook

Eclipse MicroProfile

Eclipse MicroProfile is an open standard for Java MicroServices applications: https://microprofile.io/.

MicroProfile Configuration

Standardized configuration mechanisms: https://microprofile.io/project/eclipse/microprofile-config

MicroProfile RestClient

Type-safe JAX-RS client: https://microprofile.io/project/eclipse/microprofile-rest-client

  1. Make RestClients @ApplicationScoped:

    By default, MicroProfile Rest Clients have a scope of @Dependent. When you inject them into something like a Jakarta RESTful endpoint, they inherit the scope of the Jakarta RESTful class, which is @RequestScoped by default. This will cause a new MicroProfile Rest Client to be created every time, which leads to extra CPU cost and a decent amount of class loading overhead that will slow things down. By making the MicroProfile Rest Client ApplicationScoped, the client is only created once, saving a lot of time.

    @ApplicationScoped
@Path("/")
@RegisterRestClient(configKey="appScopedRestClient")
public interface AppScopedRestClient {

  @GET
  @Path("/endpoint")
  @Produces(MediaType.TEXT_PLAIN)
  public String ping();
}

@Path("/mp-restclient-test2")
public class MicroProfileRestClientTest2 {

  @Inject @RestClient
  private AppScopedRestClient appScopedClient;
 
  @GET
  @Produces(MediaType.TEXT_PLAIN)
  public String ping() {
    return appScopedClient.ping();
  }
}

MicroProfile OpenTracing

Standardized way to trace JAX-RS requests and responses: https://microprofile.io/project/eclipse/microprofile-opentracing

MicroProfile Metrics

Standardized way to expose telemetry data: https://microprofile.io/project/eclipse/microprofile-metrics

MicroProfile OpenAPI

Standardized way to expose API documentation: https://microprofile.io/project/eclipse/microprofile-open-api

MicroProfile Fault Tolerance

Standardized methods for fault tolerance: https://microprofile.io/project/eclipse/microprofile-fault-tolerance

MicroProfile Health

Standardized application health check endpoint: https://microprofile.io/project/eclipse/microprofile-health

MicroShed Testing

MicroShed Testing helps to test MicroProfile applications.

Garbage Collection Thrashing Health Check Example

import javax.enterprise.context.ApplicationScoped;
import org.eclipse.microprofile.health.Health;
import org.eclipse.microprofile.health.HealthCheck;
import org.eclipse.microprofile.health.HealthCheckResponse;

@Health
@ApplicationScoped
public class HealthChecker implements HealthCheck
{
    public static final double HEALTH_CHECK_GC_MIN_FREE = Double
                    .parseDouble(System.getProperty("HEALTH_CHECK_GC_MIN_FREE", "0.05"));

    public static final int HEALTH_CHECK_GC_MIN_INTERVAL_MS = Integer.getInteger("HEALTH_CHECK_GC_MIN_INTERVAL_SECONDS",
                    60 * 5) * 1000;

    private static long healthCheckGcLastCheck = System.currentTimeMillis();

    @Override
    public HealthCheckResponse call()
    {
        if (isGarbageCollectionHealthy())
        {
            return HealthCheckResponse.named("healthCheck").up().build();
        }
        else
        {
            return HealthCheckResponse.named("healthCheck").down().build();
        }
    }

    public static synchronized boolean isGarbageCollectionHealthy()
    {
        try
        {
            final long now = System.currentTimeMillis();

            final boolean doCheck = now >= healthCheckGcLastCheck + HEALTH_CHECK_GC_MIN_INTERVAL_MS;

            healthCheckGcLastCheck = now;

            if (doCheck)
            {
                final int checkHeapBytes = Math.toIntExact(
                                (long) ((double) Runtime.getRuntime().maxMemory() * HEALTH_CHECK_GC_MIN_FREE));
                @SuppressWarnings("unused")
                final byte[] blob = new byte[checkHeapBytes];
            }

            return true;
        }
        catch (OutOfMemoryError oome)
        {
            return false;
        }
    }
}