jdk25 memory leak at runtime/vm/ContinuationHelpers.cpp:132

[pshipton]

Running the following test shows a memory leak at runtime/vm/ContinuationHelpers.cpp:132.

import java.util.concurrent.atomic.*;
import java.util.stream.*;
import java.util.*;

public class GTest {
public static void main(String[] args) throws Exception {
        GTest gt = new GTest();
        long startm = System.currentTimeMillis();
        for (int i = 0; i < 2000; i++) {
                if ((i + 1) % 200 == 0) {
                        long currentm = System.currentTimeMillis();
                        System.out.println("iteration " + i + " time: " + (currentm - startm));
                        startm = currentm;
                        Thread.sleep(200);
                        System.gc();
                        System.gc();
                        Thread.sleep(200);
                }
                gt.test();
        }
}
public void test() {
        AtomicInteger inc = new AtomicInteger(0);
        Stream stream = Stream.generate(inc::getAndIncrement).gather(Gatherers.mapConcurrent(40, num -> num));
        Iterator it = stream.iterator();
        for (int i = 0; i < 500; i++) {
            it.next();
        }
}
}

java -Xint -Xcheck:memory:noscan,quick,callsite=1000000 GTest &> output.txt

grep ContinuationHelpers.cpp:132 output.txt

 total alloc   | total freed   | delta alloc   | delta freed   | high water     | largest
 blocks| bytes | blocks| bytes | blocks| bytes | blocks| bytes | blocks| bytes | bytes | num   | callsite
-------+-------+-------+-------+-------+-------+-------+-------+-------+-------+-------+-------+------------ 
 989949 1383288736       0       0  989949 1383288736       0       0  989949 1383288736    4096       3 /home/jenkins/workspace/build-scripts/jobs/jdk25/jdk25-linux-x64-openj9/workspace/build/src/openj9/runtime/vm/ContinuationHelpers.cpp:132
1989916 2780566632       0       0  999967 1397277896       0       0 1989916 2780566632    4096       3 /home/jenkins/workspace/build-scripts/jobs/jdk25/jdk25-linux-x64-openj9/workspace/build/src/openj9/runtime/vm/ContinuationHelpers.cpp:132
2989894 4177877224       0       0  999978 1397310592       0       0 2989894 4177877224    4096       3 /home/jenkins/workspace/build-scripts/jobs/jdk25/jdk25-linux-x64-openj9/workspace/build/src/openj9/runtime/vm/ContinuationHelpers.cpp:132
3099696 4331308544       0       0  109802 153431320       0       0 3099696 36341248    4096       3 /home/jenkins/workspace/build-scripts/jobs/jdk25/jdk25-linux-x64-openj9/workspace/build/src/openj9/runtime/vm/ContinuationHelpers.cpp:132

Ref https://github.ibm.com/runtimes/openj9-openjdk-jdk25-zos/issues/115