diff --git a/core/lib/Drupal/Core/Test/TestDatabase.php b/core/lib/Drupal/Core/Test/TestDatabase.php
index 682c792..9bfa25d 100644
--- a/core/lib/Drupal/Core/Test/TestDatabase.php
+++ b/core/lib/Drupal/Core/Test/TestDatabase.php
@@ -115,7 +115,10 @@ protected function getTestLock() {
     // tests are run concurrently.
     do {
       $lock_id = mt_rand(10000000, 99999999);
-      if (@symlink(__FILE__, $this->getLockFile($lock_id)) === FALSE) {
+      // If we're only running with a concurrency of 1 there's no need to create
+      // a test lock file as there is no chance of the random number generated
+      // clashing.
+      if (getenv('RUN_TESTS_CONCURRENCY') > 1 && @symlink(__FILE__, $this->getLockFile($lock_id)) === FALSE) {
         $lock_id = NULL;
       }
     } while ($lock_id === NULL);
@@ -123,20 +126,6 @@ protected function getTestLock() {
   }
 
   /**
-   * Releases a test lock.
-   *
-   * This should only be called once the related test fixtures have been cleaned
-   * up.
-   */
-  public function releaseTestLock() {
-    $concurrency = getenv('RUN_TESTS_CONCURRENCY');
-    // If we're doing concurrent testing then ensure no dupes in the whole run.
-    if (!$concurrency || $concurrency == 1) {
-      unlink($this->getLockFile($this->lockId));
-    }
-  }
-
-  /**
    * Releases all test locks.
    *
    * This should only be called once all the test fixtures have been cleaned up.
diff --git a/core/modules/simpletest/src/TestBase.php b/core/modules/simpletest/src/TestBase.php
index 5fb36a4..fe25f95 100644
--- a/core/modules/simpletest/src/TestBase.php
+++ b/core/modules/simpletest/src/TestBase.php
@@ -1366,10 +1366,6 @@ private function restoreEnvironment() {
     // Delete test site directory.
     file_unmanaged_delete_recursive($this->siteDirectory, array($this, 'filePreDeleteCallback'));
 
-    // Release the test lock.
-    $test_db = new TestDatabase($test_prefix);
-    $test_db->releaseTestLock();
-
     // Restore original database connection.
     Database::removeConnection('default');
     Database::renameConnection('simpletest_original_default', 'default');
diff --git a/core/scripts/run-tests.sh b/core/scripts/run-tests.sh
index d064331..c025f7d 100755
--- a/core/scripts/run-tests.sh
+++ b/core/scripts/run-tests.sh
@@ -5,6 +5,7 @@
  * This script runs Drupal tests from command line.
  */
 
+use Drupal\Component\FileSystem\FileSystem;
 use Drupal\Component\Utility\Html;
 use Drupal\Component\Utility\Timer;
 use Drupal\Component\Uuid\Php;
@@ -455,6 +456,12 @@ function simpletest_script_init() {
   $_SERVER['HTTP_USER_AGENT'] = 'Drupal command line';
 
   if ($args['concurrency'] > 1) {
+    $directory = FileSystem::getOsTemporaryDirectory();
+    $test_symlink = @symlink(__FILE__, $directory . '/test_symlink');
+    if (!$test_symlink) {
+      throw new \RuntimeException('In order to use a concurrency higher than 1 the test system needs to be able to create symlinks in ' . $directory);
+    }
+    unlink($directory . '/test_symlink');
     putenv('RUN_TESTS_CONCURRENCY=' . $args['concurrency']);
   }
 
diff --git a/core/tests/Drupal/KernelTests/KernelTestBase.php b/core/tests/Drupal/KernelTests/KernelTestBase.php
index c34e45f..8c2492a 100644
--- a/core/tests/Drupal/KernelTests/KernelTestBase.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBase.php
@@ -701,10 +701,6 @@ protected function tearDown() {
     $this->vfsRoot = NULL;
     $this->configImporter = NULL;
 
-    // Release the prefix.
-    $test_db = new TestDatabase($test_prefix);
-    $test_db->releaseTestLock();
-
     // Free up memory: Custom test class properties.
     // Note: Private properties cannot be cleaned up.
     $rc = new \ReflectionClass(__CLASS__);
diff --git a/core/tests/Drupal/Tests/BrowserTestBase.php b/core/tests/Drupal/Tests/BrowserTestBase.php
index f9f443c..d0fabd3 100644
--- a/core/tests/Drupal/Tests/BrowserTestBase.php
+++ b/core/tests/Drupal/Tests/BrowserTestBase.php
@@ -601,10 +601,6 @@ protected function cleanupEnvironment() {
 
     // Delete test site directory.
     file_unmanaged_delete_recursive($this->siteDirectory, array($this, 'filePreDeleteCallback'));
-
-    // Release the prefix.
-    $test_db = new TestDatabase($test_prefix);
-    $test_db->releaseTestLock();
   }
 
   /**