8008188: Add regression test for 8005875

Add regression test for crash seen in 8005875. Test is run with G1 and PGCT=0 and issues "jcmd <pid> Thread.print" against itself. Without the fix for 8005875 the test will crash.

Reviewed-by: brutisso

hotspot/test/gc/TestG1ZeroPGCTJcmdThreadPrint.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2013, 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.
+ */
+
+/* @test TestG1ZeroPGCTJcmdThreadPrint
+ * @key gc
+ * @bug 8005875
+ * @summary Use jcmd to generate a thread dump of a Java program being run with PGCT=0 to verify 8005875
+ * @library /testlibrary
+ * @run main/othervm -XX:+UseG1GC -XX:ParallelGCThreads=0 -XX:+IgnoreUnrecognizedVMOptions TestG1ZeroPGCTJcmdThreadPrint
+ */
+
+import com.oracle.java.testlibrary.*;
+
+public class TestG1ZeroPGCTJcmdThreadPrint {
+  public static void main(String args[]) throws Exception {
+
+    // Grab the pid from the current java process
+    String pid = Integer.toString(ProcessTools.getProcessId());
+
+    // Create a ProcessBuilder
+    ProcessBuilder pb = new ProcessBuilder();
+
+    // Run jcmd <pid> Thread.print
+    pb.command(JDKToolFinder.getJDKTool("jcmd"), pid, "Thread.print");
+
+    OutputAnalyzer output = new OutputAnalyzer(pb.start());
+
+    // There shouldn't be a work gang for concurrent marking.
+    output.shouldNotContain("G1 Parallel Marking Threads");
+
+    // Make sure we didn't crash
+    output.shouldHaveExitValue(0);
+  }
+}