8211821: PrintStringTableStatistics crashes JVM

During JVM exit, print the Symbol and String tables before current thread gets deleted.

Reviewed-by: iklam, dholmes

test/hotspot/jtreg/runtime/PrintStringTableStats/PrintStringTableStatsTest.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import jdk.test.lib.process.ProcessTools;
+import jdk.test.lib.process.OutputAnalyzer;
+
+/*
+ * @test PrintStringTableStatsTest
+ * @bug 8211821
+ * @library /test/lib
+ * @run main PrintStringTableStatsTest
+ */
+
+public class PrintStringTableStatsTest {
+    public static void main(String... args) throws Exception {
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
+            "-XX:+PrintStringTableStatistics",
+            "--version");
+        OutputAnalyzer output = new OutputAnalyzer(pb.start());
+        output.shouldContain("Number of buckets");
+        output.shouldHaveExitValue(0);
+    }
+}