a-foundation-benchmark/src/main/java/com/ajjpj/afoundation/concurrent/jdk/j9new/ForkJoinPool.java
private boolean tryCompensate(WorkQueue w) {
        boolean canBlock;
        WorkQueue[] ws; long c; int m, pc, sp;
        if (w == null || w.qlock < 0 ||           // caller terminating
            (ws = workQueues) == null || (m = ws.length - 1) <= 0 ||
            (pc = config & SMASK) == 0)           // parallelism disabled
            canBlock = false;
        else if ((sp = (int)(c = ctl)) != 0)      // release idle worker
            canBlock = tryRelease(c, ws[sp & m], 0L);
        else {
            int ac = (int)(c >> AC_SHIFT) + pc;
            int tc = (short)(c >> TC_SHIFT) + pc;
            int nbusy = 0;                        // validate saturation
            for (int i = 0; i <= m; ++i) {        // two passes of odd indices
                WorkQueue v;
                if ((v = ws[((i << 1) | 1) & m]) != null) {
                    if ((v.scanState & SCANNING) != 0)
                        break;
                    ++nbusy;
                }
            }
            if (nbusy != (tc << 1) || ctl != c)
                canBlock = false;                 // unstable or stale
            else if (tc >= pc && ac > 1 && w.isEmpty()) {
                long nc = ((AC_MASK & (c - AC_UNIT)) |
                           (~AC_MASK & c));       // uncompensated
                canBlock = U.compareAndSwapLong(this, CTL, c, nc);
            }
            else if (tc >= MAX_CAP ||
                     (this == common && tc >= pc + commonMaxSpares))
                throw new RejectedExecutionException(
                    "Thread limit exceeded replacing blocked worker");
            else {                                // similar to tryAddWorker
                boolean add = false; int rs;      // CAS within lock
                long nc = ((AC_MASK & c) |
                           (TC_MASK & (c + TC_UNIT)));
                if (((rs = lockRunState()) & STOP) == 0)
                    add = U.compareAndSwapLong(this, CTL, c, nc);
                unlockRunState(rs, rs & ~RSLOCK);
                canBlock = add && createWorker(); // throws on exception
            }
        }
        return canBlock;
    }
private boolean tryCompensate(WorkQueue w) {
        boolean canBlock;
        WorkQueue[] ws; long c; int m, pc, sp;
        if (w == null || w.qlock < 0 ||           // caller terminating
            (ws = workQueues) == null || (m = ws.length - 1) <= 0 ||
            (pc = config & SMASK) == 0)           // parallelism disabled
            canBlock = false;
        else if ((sp = (int)(c = ctl)) != 0)      // release idle worker
            canBlock = tryRelease(c, ws[sp & m], 0L);
        else {
            int ac = (int)(c >> AC_SHIFT) + pc;
            int tc = (short)(c >> TC_SHIFT) + pc;
            int nbusy = 0;                        // validate saturation
            for (int i = 0; i <= m; ++i) {        // two passes of odd indices
                WorkQueue v;
                if ((v = ws[((i << 1) | 1) & m]) != null) {
                    if ((v.scanState & SCANNING) != 0)
                        break;
                    ++nbusy;
                }
            }
            if (nbusy != (tc << 1) || ctl != c)
                canBlock = false;                 // unstable or stale
            else if (tc >= pc && ac > 1 && w.isEmpty()) {
                long nc = ((AC_MASK & (c - AC_UNIT)) |
                           (~AC_MASK & c));       // uncompensated
                canBlock = U.compareAndSwapLong(this, CTL, c, nc);
            }
            else if (tc >= MAX_CAP ||
                     (this == common && tc >= pc + commonMaxSpares))
                throw new RejectedExecutionException(
                    "Thread limit exceeded replacing blocked worker");
            else {                                // similar to tryAddWorker
                boolean add = false; int rs;      // CAS within lock
                long nc = ((AC_MASK & c) |
                           (TC_MASK & (c + TC_UNIT)));
                if (((rs = lockRunState()) & STOP) == 0)
                    add = U.compareAndSwapLong(this, CTL, c, nc);
                unlockRunState(rs, rs & ~RSLOCK);
                canBlock = add && createWorker(); // throws on exception
            }
        }
        return canBlock;
    }
Tries to decrement active count (sometimes implicitly) and
possibly release or create a compensating worker in preparation
for blocking. Returns false (retryable by caller), on
contention, detected staleness, instability, or termination.

@param w caller