Do not load a CoroutineExceptionHandler SL eagerly on Android as it c…

…auses verification of the whole JAR/dex (-> file I/O) and ANR

Fixes #3180

kotlinx-coroutines-core/jvm/src/CoroutineExceptionHandlerImpl.kt

@@ -4,6 +4,7 @@
 
 package kotlinx.coroutines
 
+import kotlinx.coroutines.internal.*
 import java.util.*
 import kotlin.coroutines.*
 
@@ -17,14 +18,29 @@ import kotlin.coroutines.*
  * We are explicitly using the `ServiceLoader.load(MyClass::class.java, MyClass::class.java.classLoader).iterator()`
  * form of the ServiceLoader call to enable R8 optimization when compiled on Android.
  */
-private val handlers: List<CoroutineExceptionHandler> = ServiceLoader.load(
+private val handlers: List<CoroutineExceptionHandler> by lazy {
+    ServiceLoader.load(
         CoroutineExceptionHandler::class.java,
         CoroutineExceptionHandler::class.java.classLoader
-).iterator().asSequence().toList()
+    ).iterator().asSequence().toList()
+}
 
 internal actual fun initializeDefaultExceptionHandlers() {
+    /**
+     * For Android, we do not want to allow arbitrary disks read (service loader JAR scanning)
+     * as it causes ANR, so we are postponing service loading until the actual exception (crash in case of Android).
+     * For other applications it's not the issue to read the JAR, but it is the issue
+     * to read from disk/call service loader when e.g. OOM was thrown, as exception reporting will also throw,
+     * so we are initializing it eagerly.
+     *
+     * Alternatively, we can use our own FastServiceLoader (as for Dispatchers.Main) here as it gives x20 speedup, see
+     * https://github.com/Kotlin/kotlinx.coroutines/issues/878#issuecomment-445815632
+     * but it doesn't seem worth the trouble.
+     */
+    if (ANDROID_DETECTED) return
     // Load CEH and handlers
     CoroutineExceptionHandler
+    handlers
 }
 
 /**