Add test which runs Kotlin compiler in parallel

This will be useful in diagnosing issues like KT-45007 in the future.

 #KT-45007

compiler/tests-common/tests/org/jetbrains/kotlin/integration/KotlinIntegrationTestBase.java

@@ -104,7 +104,7 @@ public abstract class KotlinIntegrationTestBase extends TestCaseWithTmpdir {
         KotlinTestUtils.assertEqualsToFile(expectedFile, normalizedContent);
     }
 
-    private static int runProcess(GeneralCommandLine commandLine, StringBuilder executionLog) throws ExecutionException {
+    protected static int runProcess(GeneralCommandLine commandLine, StringBuilder executionLog) throws ExecutionException {
         OSProcessHandler handler =
                 new OSProcessHandler(commandLine.createProcess(), commandLine.getCommandLineString(), commandLine.getCharset());
 
@@ -132,7 +132,7 @@ public abstract class KotlinIntegrationTestBase extends TestCaseWithTmpdir {
         }
     }
 
-    private static File getJavaRuntime() {
+    protected static File getJavaRuntime() {
         File javaHome = new File(System.getProperty("java.home"));
         String javaExe = SystemInfo.isWindows ? "java.exe" : "java";
 

compiler/tests/org/jetbrains/kotlin/integration/ParallelBuildTest.kt

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.integration
+
+import com.intellij.execution.configurations.GeneralCommandLine
+import org.jetbrains.kotlin.cli.AbstractCliTest
+import org.jetbrains.kotlin.cli.common.ExitCode
+import org.jetbrains.kotlin.cli.jvm.K2JVMCompiler
+import org.jetbrains.kotlin.test.util.KtTestUtil
+import org.jetbrains.kotlin.utils.PathUtil.kotlinPathsForDistDirectory
+import java.io.File
+
+class ParallelBuildTest : KotlinIntegrationTestBase() {
+    fun testParallelBuild() {
+        val testDataDir = KtTestUtil.getTestDataPathBase() + "/integration/smoke/helloApp"
+        val programText = """
+            import org.jetbrains.kotlin.cli.common.messages.MessageRenderer
+            import org.jetbrains.kotlin.cli.common.ExitCode
+            import org.jetbrains.kotlin.cli.jvm.K2JVMCompiler
+            import java.util.concurrent.Executors
+            import java.util.concurrent.TimeUnit
+
+            // Increase `totalRuns` and change `threads` to `Runtime.getRuntime().availableProcessors()` to reproduce more reliably locally
+            val totalRuns = 100
+            val threads = 2
+
+            fun main() {
+                var errors = 0 
+
+                val pool = Executors.newFixedThreadPool(threads)
+                repeat(totalRuns) {
+                    pool.submit {
+                        try {
+                            val code = K2JVMCompiler().exec(
+                                System.err, MessageRenderer.PLAIN_RELATIVE_PATHS,
+                                "$testDataDir/hello.kt",
+                                "-d", "$tmpdir/output"
+                            )
+                            if (code != ExitCode.OK) errors++
+                        } catch (e: Throwable) {
+                            errors++
+                            throw e
+                        }
+                    }
+                }
+                pool.shutdown()
+                pool.awaitTermination(120L, TimeUnit.SECONDS)
+
+                println("" + errors + " errors")
+                if (errors > 0) {
+                    System.exit(1)
+                }
+            }
+        """.trimIndent()
+
+        val programSource = File(tmpdir, "program.kt")
+        programSource.writeText(programText)
+
+        val program = File(tmpdir, "program").absolutePath
+        val (output, exitCode) = AbstractCliTest.executeCompilerGrabOutput(
+            K2JVMCompiler(),
+            listOf(
+                programSource.path,
+                "-d", program,
+                "-cp", kotlinPathsForDistDirectory.compilerPath.absolutePath,
+            ),
+        )
+        assertEquals("Compilation failed:\n$output", ExitCode.OK, exitCode)
+
+        val result = runJava(
+            testDataDir,
+            "-cp",
+            listOf(
+                program,
+                kotlinPathsForDistDirectory.compilerPath.absolutePath,
+            ).joinToString(File.pathSeparator),
+            "ProgramKt",
+        )
+        assertEquals(
+            "Run failed:\n$result",
+            "OUT:\n0 errors\n\nReturn code: 0\n", result
+        )
+    }
+
+    private fun runJava(testDataDir: String, vararg arguments: String): String {
+        val commandLine = GeneralCommandLine().withWorkDirectory(testDataDir)
+        commandLine.exePath = getJavaRuntime().absolutePath
+        commandLine.addParameters(*arguments)
+        val executionLog = StringBuilder()
+        val exitCode = runProcess(commandLine, executionLog)
+        assertEquals("Non-zero exit code ($exitCode):\n$executionLog", 0, exitCode)
+        return executionLog.toString()
+    }
+}