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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

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 * 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

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 *

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/*

 * @test

 * @summary Test corner case that overflows malloc site hashtable bucket

 * @requires sun.arch.data.model == "32"

 * @key nmt jcmd stress

 * @build MallocSiteHashOverflow

 * @run main ClassFileInstaller sun.hotspot.WhiteBox

 * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:NativeMemoryTracking=detail MallocSiteHashOverflow

 */

import jdk.test.lib.*;

import sun.hotspot.WhiteBox;

public class MallocSiteHashOverflow {

    public static void main(String args[]) throws Exception {

        // Size of entries based on malloc tracking header defined in mallocTracker.hpp

        // For 32-bit systems, create 257 malloc sites with the same hash bucket to overflow a hash bucket

        long entries = 257;

        OutputAnalyzer output;

        WhiteBox wb = WhiteBox.getWhiteBox();

        int MAX_HASH_SIZE = wb.NMTGetHashSize();

        // Grab my own PID

        String pid = Integer.toString(ProcessTools.getProcessId());

        ProcessBuilder pb = new ProcessBuilder();

        // Verify that current tracking level is "detail"

        pb.command(new String[] { JDKToolFinder.getJDKTool("jcmd"), pid, "VM.native_memory", "statistics"});

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

        output.shouldContain("Native Memory Tracking Statistics");

        // Attempt to cause NMT to downgrade tracking level by allocating small amounts

        // of memory with random pseudo call stack

        int pc = 1;

        for (int i = 0; i < entries; i++) {

            long addr = wb.NMTMallocWithPseudoStack(1, pc);

            if (addr == 0) {

                throw new RuntimeException("NMTMallocWithPseudoStack: out of memory");

            }

            // We free memory here since it doesn't affect pseudo malloc alloc site hash table entries

            wb.NMTFree(addr);

            pc += MAX_HASH_SIZE;

            if (i == entries) {

                // Verify that tracking has been downgraded

                pb.command(new String[] { JDKToolFinder.getJDKTool("jcmd"), pid, "VM.native_memory", "statistics"});

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

                output.shouldContain("Tracking level has been downgraded due to lack of resources");

            }

        }

    }

}