fix the open issue #11794

http-client-core/src/main/java/io/micronaut/http/client/exceptions/ReadTimeoutException.java

@@ -15,6 +15,8 @@
  */
 package io.micronaut.http.client.exceptions;
 
+import io.micronaut.core.annotation.Nullable;
+
 /**
  * An exception thrown when a read timeout occurs.
  *
@@ -23,9 +25,14 @@
  */
 public final class ReadTimeoutException extends HttpClientException {
 
-    public static final ReadTimeoutException TIMEOUT_EXCEPTION = new ReadTimeoutException();
+    public static final ReadTimeoutException TIMEOUT_EXCEPTION = new ReadTimeoutException("Read Timeout");
+
+    public ReadTimeoutException(String message) {
+        super(message);
+    }
 
-    private ReadTimeoutException() {
-        super("Read Timeout", null, true);
+    public ReadTimeoutException(String message, @Nullable String serviceId) {
+        super(message);
+        setServiceId(serviceId);
     }
 }

http-client/src/main/java/io/micronaut/http/client/netty/DefaultHttpClient.java

@@ -918,7 +918,7 @@ private <I, O, E> Mono<HttpResponse<O>> exchange(io.micronaut.http.HttpRequest<I
                 mono = mono.timeout(requestTimeout, scheduler.get(), null)
                     .onErrorResume(throwable -> {
                         if (throwable instanceof TimeoutException) {
-                            return ExecutionFlow.error(ReadTimeoutException.TIMEOUT_EXCEPTION);
+                            return ExecutionFlow.error(new ReadTimeoutException("Read Timeout", informationalServiceId));
                         }
                         return ExecutionFlow.error(throwable);
                     });
@@ -2050,7 +2050,7 @@ private <E extends HttpClientException> E decorate(E exc) {
         } else if (cause instanceof io.micronaut.http.exceptions.BufferLengthExceededException blee) {
             result = decorate(new ContentLengthExceededException(blee.getAdvertisedLength(), blee.getReceivedLength()));
         } else if (cause instanceof io.netty.handler.timeout.ReadTimeoutException) {
-            result = ReadTimeoutException.TIMEOUT_EXCEPTION;
+            result = new ReadTimeoutException("Read Timeout", informationalServiceId);
         } else if (cause instanceof HttpClientException hce) {
             result = decorate(hce);
         } else {

reproduce_issue.groovy

@@ -0,0 +1,83 @@
+import groovy.transform.Field
+
+@Field
+String testSource = """
+package io.micronaut.reproduce
+
+import io.micronaut.http.client.exceptions.ReadTimeoutException
+import spock.lang.Specification
+import io.micronaut.http.client.exceptions.HttpClientException
+
+/**
+ * Reproduces the issue where ReadTimeoutException's serviceId remains null
+ * due to HttpClientException's `serviceIdLocked` flag being set during
+ * ReadTimeoutException's construction.
+ *
+ * If this test passes, the issue is reproduced (serviceId is null after attempting to set,
+ * and an IllegalStateException is thrown upon attempt).
+ * If this test fails, the issue is resolved (serviceId can be set).
+ */
+class ReproduceIssueSpec extends Specification {
+
+    void "ReadTimeoutException serviceId is null and cannot be set"() {
+        setup:
+        // Use the static final instance as there is no public constructor for ReadTimeoutException
+        HttpClientException exception = ReadTimeoutException.TIMEOUT_EXCEPTION
+
+        when: "An attempt is made to set the serviceId on the shared ReadTimeoutException instance"
+        exception.setServiceId("test-service-id")
+
+        then: "An IllegalStateException should be thrown, indicating that the serviceId cannot be set"
+        thrown(IllegalStateException)
+
+        and: "The serviceId on the exception should remain null after the failed attempt"
+        // Note: The `thrown` block intercepts the exception, so subsequent `and:` blocks
+        // are still executed. If the exception was thrown, the serviceId would indeed remain null.
+        exception.getServiceId() == null
+    }
+}
+"""
+
+def testDir = new File("test-suite/src/test/groovy/io/micronaut/reproduce")
+def exitCode = 1 // Default to error
+
+try {
+    testDir.mkdirs()
+    def testFile = new File(testDir, "ReproduceIssueSpec.groovy")
+    testFile.write(testSource)
+
+    println "Executing test to reproduce the issue..."
+    // Target the 'test-suite' project where the test file is located
+    def command = "./gradlew :test-suite:test --tests io.micronaut.reproduce.ReproduceIssueSpec"
+    def process = command.execute()
+    process.waitForProcessOutput(System.out, System.err)
+    def gradleExitValue = process.exitValue()
+
+    // Gradle test exit codes:
+    // 0: All tests passed
+    // >0: Tests failed or other Gradle error
+
+    if (gradleExitValue == 0) {
+        // If the Spock test "ReadTimeoutException serviceId is null and cannot be set" passes,
+        // it means the IllegalStateException was thrown AND getServiceId() was null,
+        // which confirms the issue IS reproduced.
+        println "Test passed: ReadTimeoutException's serviceId remained null and could not be set. Issue reproduced (exit code 129)."
+        exitCode = 129
+    } else {
+        // If the Spock test failed, it means either the IllegalStateException was NOT thrown
+        // or getServiceId() was NOT null, meaning the issue is NOT reproduced/fixed.
+        println "Test failed: ReadTimeoutException's serviceId was settable or the expected exception was not thrown. Issue NOT reproduced (exit code 0)."
+        exitCode = 0
+    }
+
+} catch (Exception e) {
+    e.printStackTrace()
+    exitCode = 1 // Script error
+} finally {
+    // Clean up the created test file and directory
+    if (testDir.exists()) {
+        testDir.deleteDir()
+    }
+}
+
+System.exit(exitCode)