62 JDK Interception Points: In-Process Chaos Engineering with a Java Agent

                      // 62 interception targets across the JDK surface
Sealed interface ChaosSelector permits
    ThreadSelector,       // Thread.start, pool operations
    ExecutorSelector,     // ThreadPoolExecutor, ForkJoinPool
    QueueSelector,        // BlockingQueue operations
    FutureSelector,       // CompletableFuture
    SocketSelector,       // Socket, ServerSocket
    NioSelector,          // SocketChannel, Selector
    JdbcSelector,         // DataSource.getConnection, Statement
    HttpSelector,         // HttpURLConnection, HttpClient
    DnsSelector,          // InetAddress resolution
    SslSelector,          // SSLEngine, SSLSocket
    ClockSelector,        // System.currentTimeMillis, nanoTime
    GcSelector,           // System.gc
    ClassloadingSelector, // ClassLoader.loadClass
    SerializationSelector,// ObjectInputStream, ObjectOutputStream
    ThreadLocalSelector,  // ThreadLocal.get, set
    VirtualThreadSelector;// VirtualThread lifecycle
                    

                      // Hot path after JIT compilation — effectively just:
public static void connect(Socket socket, SocketAddress endpoint, int timeout) {
    Object delegate = BootstrapDispatcher.delegate;  // volatile read
    if (delegate != null) {                           // null check — fast path
        BootstrapDispatcher.handles[SOCKET_CONNECT]   // MethodHandle
            .invoke(delegate, socket, endpoint);       // → ChaosRuntime
    }
    originalConnect(socket, endpoint, timeout);       // real JDK call
}
// Zero-scenario overhead: one volatile read + one null check + one untaken branch
// Measured: ~60 ns per call in the uncontested case after warm-up
                    

                      @ChaosTest  // @SpringBootTest composed annotation
class OrderServiceChaosTest {

    @Test
    void retryLogic_handles_transient_jdbc_failures(ChaosSession session) {
        var scenario = ChaosScenario.builder("transient-db")
            .selector(ChaosSelector.jdbc(OperationType.JDBC_CONNECTION_ACQUIRE))
            .effect(ChaosEffect.reject("chaos: simulated pool timeout"))
            .activationPolicy(ActivationPolicy.builder()
                .probability(1.0)
                .maxApplications(2)   // First 2 borrows fail, 3rd succeeds
                .build())
            .build();

        try (var handle = session.activate(scenario)) {
            try (var scope = session.bind()) {
                // This thread and any executor tasks it submits
                // will see the JDBC failures — nothing else will
                var result = orderService.placeOrder(testOrder);
                assertThat(result.status()).isEqualTo(OrderStatus.CONFIRMED);
            }
        }
        // Chaos cleaned up — next test is unaffected
    }
}
                    

                      <!-- Spring Boot 3 — add to pom.xml testImplementation -->
<dependency>
    <groupId>com.macstab.chaos</groupId>
    <artifactId>chaos-agent-spring-boot3-test-starter</artifactId>
    <version>${chaos-agent.version}</version>
    <scope>test</scope>
</dependency>

<!-- That's it. No -javaagent flag. No JVM args. No beans to define. -->

<!-- Spring Boot 4 -->
<dependency>
    <groupId>com.macstab.chaos</groupId>
    <artifactId>chaos-agent-spring-boot4-test-starter</artifactId>
    <version>${chaos-agent.version}</version>
    <scope>test</scope>
</dependency>
                    

                      @SpringBootTest
@ChaosTest
class PaymentSLAChaosTest {

    @Autowired PaymentService paymentService;

    @Test
    void payment_meets_sla_under_intermittent_jdbc_pressure(ChaosSession session) {
        // Activate 20% JDBC connection failure — simulates pool under load
        var jdbcChaos = ChaosScenario.builder("jdbc-pressure")
            .selector(ChaosSelector.jdbc(OperationType.JDBC_CONNECTION_ACQUIRE))
            .effect(ChaosEffect.delay(Duration.ofMillis(150)))  // Not rejection — delay
            .activationPolicy(ActivationPolicy.probability(0.20))
            .build();

        // Also activate a background heap stressor
        var heapStressor = ChaosScenario.builder("heap-pressure")
            .effect(ChaosEffect.stressor(StressorType.HEAP_PRESSURE)
                .retainMbPerSecond(50)
                .build())
            .build();

        try (var h1 = session.activate(jdbcChaos);
             var h2 = session.activate(heapStressor)) {

            try (var scope = session.bind()) {
                long start = System.nanoTime();
                var result = paymentService.process(testPayment);
                long elapsedMs = (System.nanoTime() - start) / 1_000_000;

                assertThat(result.status()).isEqualTo(PaymentStatus.COMPLETED);
                assertThat(elapsedMs).isLessThan(500);  // SLA: p99 < 500ms
            }
        }
    }
}