Remove ThreadTracker from gradle plugin

ThreadTracker was introduced to detect memory leaks
when using gradle daemon. However, it makes
quite strong assumption about build lifecycle:
there should not be any builds started after
kotlin plugin is configured that are alive when
buildFinished callback is called.

This assumption can be broken by some gradle configurations
namely our android tests and gradle 2.13-rc.

Since we already have daemon memory leak test (KotlinGradlePluginIT#testKotlinOnlyDaemonMemory),
after some discussion it was decided to remove ThreadTracker

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/CleanUpBuildListener.kt

@@ -21,9 +21,7 @@ import org.gradle.BuildAdapter
 import org.gradle.BuildResult
 import org.gradle.api.Project
 import org.gradle.api.logging.Logging
-import org.gradle.api.tasks.compile.AbstractCompile
 import java.util.concurrent.ScheduledExecutorService
-import kotlin.properties.Delegates
 
 
 private fun comparableVersionStr(version: String) =
@@ -42,7 +40,6 @@ class CleanUpBuildListener(pluginClassLoader: ClassLoader, private val project:
     }
 
     private val log = Logging.getLogger(this.javaClass)
-    private var threadTracker: ThreadTracker? = ThreadTracker()
     private val cleanup = CompilerServicesCleanup(pluginClassLoader)
     private var startMemory: Long? = null
 
@@ -65,15 +62,11 @@ class CleanUpBuildListener(pluginClassLoader: ClassLoader, private val project:
                 log.kotlinDebug("Cleanup after kotlin")
 
                 cleanup(gradle.gradleVersion)
-
-                // checking thread leaks only then cleaning up
-                threadTracker?.checkThreadLeak(gradle)
             }
             else {
                 log.kotlinDebug("Skipping kotlin cleanup since compiler wasn't called")
             }
 
-            threadTracker = null
             gradle.removeListener(this)
 
             if (kotlinCompilerCalled) {

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/ThreadTracker.kt

@@ -1,42 +0,0 @@
-package org.jetbrains.kotlin.gradle.plugin
-
-import org.gradle.api.invocation.Gradle
-import org.gradle.api.logging.Logging
-import java.util.*
-
-class ThreadTracker {
-    val log = Logging.getLogger(this.javaClass)
-    private var before: Collection<Thread>? = getThreads()
-
-    private fun getThreads(): Collection<Thread> = Thread.getAllStackTraces().keys
-
-    fun checkThreadLeak(gradle: Gradle?) {
-        try {
-            val testThreads = gradle != null && gradle.rootProject.hasProperty(ASSERT_THREAD_LEAKS_PROPERTY)
-
-            Thread.sleep(if (testThreads) 200L else 50L)
-
-            val after = HashSet(getThreads())
-            after.removeAll(before!!)
-
-            for (thread in after) {
-                if (thread == Thread.currentThread()) continue
-
-                val name = thread.name
-
-                if (testThreads) {
-                    throw RuntimeException("Thread leaked: $thread: $name\n ${thread.stackTrace.joinToString(separator = "\n", prefix = " at ")}")
-                }
-                else {
-                    log.info("Thread leaked: $thread: $name")
-                }
-            }
-        } finally {
-            before = null
-        }
-    }
-
-    companion object {
-        const val ASSERT_THREAD_LEAKS_PROPERTY = "kotlin.gradle.test.assertThreadLeaks"
-    }
-}

libraries/tools/kotlin-gradle-plugin/src/test/kotlin/org/jetbrains/kotlin/gradle/AbstractKotlinAndroidGradleTests.kt

@@ -13,7 +13,6 @@ abstract class AbstractKotlinAndroidGradleTests(
 
     override fun defaultBuildOptions() =
             BuildOptions(withDaemon = true,
-                         assertThreadLeaks = false,
                          androidHome = File("../../../dependencies/android-sdk-for-tests"),
                          androidGradlePluginVersion = androidGradlePluginVersion)
 

libraries/tools/kotlin-gradle-plugin/src/test/kotlin/org/jetbrains/kotlin/gradle/BaseGradleIT.kt

@@ -3,7 +3,6 @@ package org.jetbrains.kotlin.gradle
 import com.google.common.io.Files
 import com.intellij.openapi.util.io.FileUtil
 import org.gradle.api.logging.LogLevel
-import org.jetbrains.kotlin.gradle.plugin.ThreadTracker
 import org.jetbrains.kotlin.gradle.util.createGradleCommand
 import org.jetbrains.kotlin.gradle.util.runProcess
 import org.junit.After
@@ -71,10 +70,6 @@ abstract class BaseGradleIT {
             val withDaemon: Boolean = false,
             val daemonOptionSupported: Boolean = true,
             val incremental: Boolean? = null,
-            /**
-             * @see [ThreadTracker]
-             */
-            val assertThreadLeaks: Boolean = true,
             val androidHome: File? = null,
             val androidGradlePluginVersion: String? = null)
 
@@ -212,9 +207,6 @@ abstract class BaseGradleIT {
                 }
 
                 add("-PpathToKotlinPlugin=" + File("local-repo").absolutePath)
-                if (options.assertThreadLeaks) {
-                    add("-P${ThreadTracker.ASSERT_THREAD_LEAKS_PROPERTY}=true")
-                }
                 options.incremental?.let { add("-Pkotlin.incremental=$it") }
                 options.androidGradlePluginVersion?.let { add("-PandroidToolsVersion=$it")}
             }

libraries/tools/kotlin-gradle-plugin/src/test/kotlin/org/jetbrains/kotlin/gradle/Kotlin2JsGradlePluginIT.kt

@@ -1,15 +1,13 @@
 package org.jetbrains.kotlin.gradle
 
 import org.junit.Test
-import org.jetbrains.kotlin.gradle.BaseGradleIT.Project
-
 
 class Kotlin2JsGradlePluginIT : BaseGradleIT() {
     @Test
     fun testBuildAndClean() {
         val project = Project("kotlin2JsProject", "1.6")
 
-        project.build("build", "-Pkotlin.gradle.noThreadTest=true") {
+        project.build("build") {
             assertSuccessful()
             assertReportExists()