[JENKINS-72016] Define a thread pool for ProxyConfiguration’s `Http…

…Client` (#8490)

* Define a thread pool for `ProxyConfiguration`’s `HttpClient`

* Skip test on Windows #8490 (comment)

core/src/main/java/hudson/ProxyConfiguration.java

@@ -31,7 +31,9 @@
 import hudson.model.Descriptor;
 import hudson.model.Saveable;
 import hudson.model.listeners.SaveableListener;
+import hudson.util.DaemonThreadFactory;
 import hudson.util.FormValidation;
+import hudson.util.NamingThreadFactory;
 import hudson.util.Scrambler;
 import hudson.util.Secret;
 import hudson.util.XStream2;
@@ -58,6 +60,8 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 import java.util.regex.Pattern;
 import jenkins.UserAgentURLConnectionDecorator;
@@ -370,6 +374,8 @@ public static HttpClient newHttpClient() {
         return newHttpClientBuilder().followRedirects(HttpClient.Redirect.NORMAL).build();
     }
 
+    private static final Executor httpClientExecutor = Executors.newCachedThreadPool(new NamingThreadFactory(new DaemonThreadFactory(), "Jenkins HttpClient"));
+
     /**
      * Create a new {@link HttpClient.Builder} preconfigured with Jenkins-specific default settings.
      *
@@ -397,6 +403,7 @@ public static HttpClient.Builder newHttpClientBuilder() {
         if (DEFAULT_CONNECT_TIMEOUT_MILLIS > 0) {
             httpClientBuilder.connectTimeout(Duration.ofMillis(DEFAULT_CONNECT_TIMEOUT_MILLIS));
         }
+        httpClientBuilder.executor(httpClientExecutor);
         return httpClientBuilder;
     }
 

test/src/test/java/hudson/ProxyConfigurationTest.java

@@ -0,0 +1,71 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2023 CloudBees, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package hudson;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+
+import hudson.model.InvisibleAction;
+import hudson.model.UnprotectedRootAction;
+import java.net.URI;
+import org.junit.Assume;
+import org.junit.Rule;
+import org.junit.Test;
+import org.jvnet.hudson.test.JenkinsRule;
+import org.jvnet.hudson.test.TestExtension;
+import org.kohsuke.stapler.HttpResponse;
+import org.kohsuke.stapler.HttpResponses;
+
+public final class ProxyConfigurationTest {
+
+    @Rule
+    public JenkinsRule r = new JenkinsRule();
+
+    @Test
+    public void httpClientExecutor() throws Exception {
+        Assume.assumeFalse("Too slow on Windows", Functions.isWindows());
+        for (int i = 0; i < 50_000; i++) {
+            if (i % 1_000 == 0) {
+                System.err.println("#" + i);
+            }
+            assertThat(ProxyConfiguration.newHttpClient().send(ProxyConfiguration.newHttpRequestBuilder(URI.create(r.getURL() + "ping/")).build(),
+                    java.net.http.HttpResponse.BodyHandlers.discarding()).statusCode(),
+                is(200));
+        }
+    }
+
+    @TestExtension("httpClientExecutor")
+    public static final class Ping extends InvisibleAction implements UnprotectedRootAction {
+        @Override
+        public String getUrlName() {
+            return "ping";
+        }
+
+        public HttpResponse doIndex() {
+            return HttpResponses.ok();
+        }
+    }
+
+}