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 *

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 * published by the Free Software Foundation.

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 * 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

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 */

/*

 * @test

 * @bug 8140520

 * @summary Setting small CompilerThreadStackSize, ThreadStackSize, and

 * VMThreadStackSize values should result in an error message that shows

 * the minimum stack size value for each thread type.

 * @library /test/lib

 * @modules java.base/jdk.internal.misc

 *          java.management

 * @run main TooSmallStackSize

 */

/*

 * The primary purpose of this test is to make sure we can run with a

 * stack smaller than the minimum without crashing. Also this test will

 * determine the minimum allowed stack size for the platform (as

 * provided by the JVM error message when a very small stack is used),

 * and then verify that the JVM can be launched with that stack size

 * without a crash or any error messages.

 *

 * Note: The '-Xss<size>' and '-XX:ThreadStackSize=<k-bytes>' options

 * both control Java thread stack size. This repo's version of the test

 * exercises the '-XX:ThreadStackSize' VM option. The jdk repo's version

 * of the test exercises the '-Xss' option.

 */

import jdk.test.lib.process.ProcessTools;

import jdk.test.lib.process.OutputAnalyzer;

public class TooSmallStackSize {

    /* for debugging. Normally false. */

    static final boolean verbose = false;

    static final String CompilerThreadStackSizeString = "CompilerThreadStackSize";

    static final String ThreadStackSizeString = "Java thread stack size";

    static final String VMThreadStackSizeString = "VMThreadStackSize";

    /*

     * Returns the minimum stack size this platform will allowed based on the

     * contents of the error message the JVM outputs when too small of a

     * stack size was used.

     *

     * The testOutput argument must contain the result of having already run

     * the JVM with too small of a stack size.

     */

    static String getMinStackAllowed(String testOutput) {

        /*

         * The JVM output will contain in one of the lines:

         *   "The CompilerThreadStackSize specified is too small. Specify at least 100k"

         *   "The Java thread stack size specified is too small. Specify at least 100k"

         *   "The VMThreadStackSize specified is too small. Specify at least 100k"

         * Although the actual size will vary. We need to extract this size

         * string from the output and return it.

         */

        String matchStr = "Specify at least ";

        int match_idx = testOutput.indexOf(matchStr);

        if (match_idx >= 0) {

            int size_start_idx = match_idx + matchStr.length();

            int k_start_idx = testOutput.indexOf("k", size_start_idx);

            // don't include the 'k'; the caller will have to

            // add it back as needed.

            return testOutput.substring(size_start_idx, k_start_idx);

        }

        System.out.println("Expect='" + matchStr + "'");

        System.out.println("Actual: " + testOutput);

        System.out.println("FAILED: Could not get the stack size from the output");

        throw new RuntimeException("test fails");

    }

    /*

     * Run the JVM with the specified stack size.

     *

     * Returns the minimum allowed stack size gleaned from the error message,

     * if there is an error message. Otherwise returns the stack size passed in.

     */

    static String checkStack(String stackOption, String optionMesg, String stackSize) throws Exception {

        String min_stack_allowed;

        System.out.println("*** Testing " + stackOption + stackSize);

        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(

            stackOption + stackSize,

            // Uncomment the following to get log output

            // that shows actual thread creation sizes.

            // "-Xlog:os+thread",

            "-version");

        OutputAnalyzer output = new OutputAnalyzer(pb.start());

        if (verbose) {

            System.out.println("stdout: " + output.getStdout());

        }

        if (output.getExitValue() == 0) {

            // checkMinStackAllowed() is called with stackSize values

            // that should be the minimum that works. This method,

            // checkStack(), is called with stackSize values that

            // should be too small and result in error messages.

            // However, some platforms fix up a stackSize value that is

            // too small into something that works so we have to allow

            // for checkStack() calls that work.

            System.out.println("PASSED: got exit_code == 0 with " + stackOption + stackSize);

            min_stack_allowed = stackSize;

        } else {

            String expect = "The " + optionMesg + " specified is too small";

            if (verbose) {

                System.out.println("Expect='" + expect + "'");

            }

            output.shouldContain(expect);

            min_stack_allowed = getMinStackAllowed(output.getStdout());

            System.out.println("PASSED: got expected error message with " + stackOption + stackSize);

        }

        return min_stack_allowed;

    }

    /*

     * Run the JVM with the minimum allowed stack size. This should always succeed.

     */

    static void checkMinStackAllowed(String stackOption, String optionMesg, String stackSize) throws Exception {

        System.out.println("*** Testing " + stackOption + stackSize);

        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(

            stackOption + stackSize,

            // Uncomment the following to get log output

            // that shows actual thread creation sizes.

            // "-Xlog:os+thread",

            "-version");

        OutputAnalyzer output = new OutputAnalyzer(pb.start());

        output.shouldHaveExitValue(0);

        System.out.println("PASSED: VM launched with " + stackOption + stackSize);

    }

    public static void main(String... args) throws Exception {

        /*

         * The result of a 16k stack size should be a quick exit with a complaint

         * that the stack size is too small. However, for some win32 builds, the

         * stack is always at least 64k, and this also sometimes is the minimum

         * allowed size, so we won't see an error in this case.

         *

         * This test case will also produce a crash on some platforms if the fix

         * for 6762191 is not yet in place.

         */

        checkStack("-XX:ThreadStackSize=", ThreadStackSizeString, "16");

        /*

         * Try with a 32k stack size, which is the size that the launcher will

         * set to if you try setting to anything smaller. This should produce the same

         * result as setting to 16k if the fix for 6762191 is in place.

         */

        String min_stack_allowed = checkStack("-XX:ThreadStackSize=", ThreadStackSizeString, "32");

        /*

         * Try again with a the minimum stack size that was given in the error message

         */

        checkMinStackAllowed("-XX:ThreadStackSize=", ThreadStackSizeString, min_stack_allowed);

        /*

         * Now redo the same tests with the compiler thread stack size:

         */

        checkStack("-XX:CompilerThreadStackSize=", CompilerThreadStackSizeString, "16");

        min_stack_allowed = checkStack("-XX:CompilerThreadStackSize=", CompilerThreadStackSizeString, "32");

        checkMinStackAllowed("-XX:CompilerThreadStackSize=", CompilerThreadStackSizeString, min_stack_allowed);

        /*

         * Now redo the same tests with the VM thread stack size:

         */

        checkStack("-XX:VMThreadStackSize=", VMThreadStackSizeString, "16");

        min_stack_allowed = checkStack("-XX:VMThreadStackSize=", VMThreadStackSizeString, "32");

        checkMinStackAllowed("-XX:VMThreadStackSize=", VMThreadStackSizeString, min_stack_allowed);

    }

}