a-foundation-benchmark/src/main/java/com/ajjpj/afoundation/concurrent/jdk/j9new/ForkJoinPool.java
final int helpComplete(WorkQueue w, CountedCompleter<?> task,
                           int maxTasks) {
        WorkQueue[] ws; int s = 0, m;
        if ((ws = workQueues) != null && (m = ws.length - 1) >= 0 &&
            task != null && w != null) {
            int mode = w.config;                 // for popCC
            int r = w.hint ^ w.top;              // arbitrary seed for origin
            int origin = r & m;                  // first queue to scan
            int h = 1;                           // 1:ran, >1:contended, <0:hash
            for (int k = origin, oldSum = 0, checkSum = 0;;) {
                CountedCompleter<?> p; WorkQueue q;
                if ((s = task.status) < 0)
                    break;
                if (h == 1 && (p = w.popCC(task, mode)) != null) {
                    p.doExec();                  // run local task
                    if (maxTasks != 0 && --maxTasks == 0)
                        break;
                    origin = k;                  // reset
                    oldSum = checkSum = 0;
                }
                else {                           // poll other queues
                    if ((q = ws[k]) == null)
                        h = 0;
                    else if ((h = q.pollAndExecCC(task)) < 0)
                        checkSum += h;
                    if (h > 0) {
                        if (h == 1 && maxTasks != 0 && --maxTasks == 0)
                            break;
                        r ^= r << 13; r ^= r >>> 17; r ^= r << 5; // xorshift
                        origin = k = r & m;      // move and restart
                        oldSum = checkSum = 0;
                    }
                    else if ((k = (k + 1) & m) == origin) {
                        if (oldSum == (oldSum = checkSum))
                            break;
                        checkSum = 0;
                    }
                }
            }
        }
        return s;
    }
final int helpComplete(WorkQueue w, CountedCompleter<?> task,
                           int maxTasks) {
        WorkQueue[] ws; int s = 0, m;
        if ((ws = workQueues) != null && (m = ws.length - 1) >= 0 &&
            task != null && w != null) {
            int mode = w.config;                 // for popCC
            int r = w.hint ^ w.top;              // arbitrary seed for origin
            int origin = r & m;                  // first queue to scan
            int h = 1;                           // 1:ran, >1:contended, <0:hash
            for (int k = origin, oldSum = 0, checkSum = 0;;) {
                CountedCompleter<?> p; WorkQueue q;
                if ((s = task.status) < 0)
                    break;
                if (h == 1 && (p = w.popCC(task, mode)) != null) {
                    p.doExec();                  // run local task
                    if (maxTasks != 0 && --maxTasks == 0)
                        break;
                    origin = k;                  // reset
                    oldSum = checkSum = 0;
                }
                else {                           // poll other queues
                    if ((q = ws[k]) == null)
                        h = 0;
                    else if ((h = q.pollAndExecCC(task)) < 0)
                        checkSum += h;
                    if (h > 0) {
                        if (h == 1 && maxTasks != 0 && --maxTasks == 0)
                            break;
                        r ^= r << 13; r ^= r >>> 17; r ^= r << 5; // xorshift
                        origin = k = r & m;      // move and restart
                        oldSum = checkSum = 0;
                    }
                    else if ((k = (k + 1) & m) == origin) {
                        if (oldSum == (oldSum = checkSum))
                            break;
                        checkSum = 0;
                    }
                }
            }
        }
        return s;
    }
Tries to steal and run tasks within the target's computation.
Uses a variant of the top-level algorithm, restricted to tasks
with the given task as ancestor: It prefers taking and running
eligible tasks popped from the worker's own queue (via
popCC). Otherwise it scans others, randomly moving on
contention or execution, deciding to give up based on a
checksum (via return codes frob pollAndExecCC). The maxTasks
argument supports external usages; internal calls use zero,
allowing unbounded steps (external calls trap non-positive
values).

@param w caller
@param maxTasks if non-zero, the maximum number of other tasks to run
@return task status on exit