[Experiment] default to Loom on

build.gradle.kts

@@ -85,7 +85,7 @@ subprojects {
 
   configure<JavaPluginExtension> {
     toolchain {
-      languageVersion.set(JavaLanguageVersion.of(17))
+      languageVersion.set(JavaLanguageVersion.of(21))
     }
   }
 
@@ -202,7 +202,7 @@ subprojects {
   }
 
   tasks.withType<JavaCompile> {
-    sourceCompatibility = JavaVersion.VERSION_1_8.toString()
+    sourceCompatibility = JavaVersion.VERSION_21.toString()
     targetCompatibility = JavaVersion.VERSION_1_8.toString()
   }
 }
@@ -213,7 +213,7 @@ subprojects {
     dokkaSourceSets.configureEach {
       reportUndocumented.set(false)
       skipDeprecated.set(true)
-      jdkVersion.set(8)
+      jdkVersion.set(21)
       perPackageOption {
         matchingRegex.set(".*\\.internal.*")
         suppress.set(true)

okhttp/src/main/kotlin/okhttp3/Dispatcher.kt

@@ -19,13 +19,17 @@ import java.util.ArrayDeque
 import java.util.Collections
 import java.util.Deque
 import java.util.concurrent.ExecutorService
+import java.util.concurrent.Executors
+import java.util.concurrent.Executors.newVirtualThreadPerTaskExecutor
 import java.util.concurrent.SynchronousQueue
 import java.util.concurrent.ThreadPoolExecutor
 import java.util.concurrent.TimeUnit
+import okhttp3.internal.SuppressSignatureCheck
 import okhttp3.internal.assertThreadDoesntHoldLock
 import okhttp3.internal.connection.RealCall
 import okhttp3.internal.connection.RealCall.AsyncCall
 import okhttp3.internal.okHttpName
+import okhttp3.internal.platform.Platform
 import okhttp3.internal.threadFactory
 
 /**
@@ -88,12 +92,18 @@ class Dispatcher() {
 
   private var executorServiceOrNull: ExecutorService? = null
 
+  @SuppressSignatureCheck
   @get:Synchronized
   @get:JvmName("executorService") val executorService: ExecutorService
     get() {
       if (executorServiceOrNull == null) {
-        executorServiceOrNull = ThreadPoolExecutor(0, Int.MAX_VALUE, 60, TimeUnit.SECONDS,
+        executorServiceOrNull = if (Platform.majorVersion < 21) {
+          ThreadPoolExecutor(0, Int.MAX_VALUE, 60, TimeUnit.SECONDS,
             SynchronousQueue(), threadFactory("$okHttpName Dispatcher", false))
+        } else {
+          @Suppress("Since15")
+          newVirtualThreadPerTaskExecutor()
+        }
       }
       return executorServiceOrNull!!
     }

okhttp/src/main/kotlin/okhttp3/internal/SuppressSignatureCheck.kt

@@ -2,11 +2,9 @@ package okhttp3.internal
 
 import java.lang.annotation.Documented
 import kotlin.annotation.AnnotationRetention.BINARY
-import kotlin.annotation.AnnotationTarget.CLASS
-import kotlin.annotation.AnnotationTarget.CONSTRUCTOR
-import kotlin.annotation.AnnotationTarget.FUNCTION
+import kotlin.annotation.AnnotationTarget.*
 
 @Retention(BINARY)
 @Documented
-@Target(CONSTRUCTOR, CLASS, FUNCTION)
+@Target(CONSTRUCTOR, CLASS, FUNCTION, PROPERTY)
 internal annotation class SuppressSignatureCheck

okhttp/src/main/kotlin/okhttp3/internal/platform/Platform.kt

@@ -293,5 +293,16 @@ open class Platform {
       }
       return result.readByteArray()
     }
+
+    val majorVersion: Int by lazy {
+      when (val jvmSpecVersion = getJvmSpecVersion()) {
+        "1.8" -> 8
+        else -> jvmSpecVersion.toInt()
+      }
+    }
+
+    fun getJvmSpecVersion(): String {
+      return System.getProperty("java.specification.version", "unknown")
+    }
   }
 }