@Override
  public <T extends MemorySegment> void release(Collection<T> segments) {

    // sanity checks
    if (segments == null) {
      return;
    }

    // -------------------- BEGIN CRITICAL SECTION -------------------
    synchronized (this.lock) {
      if (this.isShutDown) {
        throw new IllegalStateException("Memory manager has been shut down.");
      }

      final Iterator<T> segmentsIterator = segments.iterator();

      AbstractInvokable lastOwner = null;
      Set<DefaultMemorySegment> segsForOwner = null;

      // go over all segments
      while (segmentsIterator.hasNext()) {

        final MemorySegment seg = segmentsIterator.next();
        if (seg.isFreed()) {
          continue;
        }

        final DefaultMemorySegment defSeg = (DefaultMemorySegment) seg;
        final AbstractInvokable owner = defSeg.owner;

        try {
          // get the list of segments by this owner only if it is a different owner than for
          // the previous one (or it is the first segment)
          if (lastOwner != owner) {
            lastOwner = owner;
            segsForOwner = this.allocatedSegments.get(owner);
          }

          // remove the segment from the list
          if (segsForOwner != null) {
            segsForOwner.remove(defSeg);
            if (segsForOwner.isEmpty()) {
              this.allocatedSegments.remove(owner);
            }
          }
        } catch (Throwable t) {
          LOG.error("Error removing book-keeping reference to allocated memory segment.", t);
        } finally {
          // release the memory in any case
          byte[] buffer = defSeg.destroy();
          this.freeSegments.add(buffer);
        }
      }

      segments.clear();
    }
    // -------------------- END CRITICAL SECTION -------------------
  }
  @Override
  public void release(MemorySegment segment) {
    // check if segment is null or has already been freed
    if (segment == null || segment.isFreed() || !(segment instanceof DefaultMemorySegment)) {
      return;
    }

    final DefaultMemorySegment defSeg = (DefaultMemorySegment) segment;
    final AbstractInvokable owner = defSeg.owner;

    // -------------------- BEGIN CRITICAL SECTION -------------------
    synchronized (this.lock) {
      if (this.isShutDown) {
        throw new IllegalStateException("Memory manager has been shut down.");
      }

      // remove the reference in the map for the owner
      try {
        Set<DefaultMemorySegment> segsForOwner = this.allocatedSegments.get(owner);

        if (segsForOwner != null) {
          segsForOwner.remove(defSeg);
          if (segsForOwner.isEmpty()) {
            this.allocatedSegments.remove(owner);
          }
        }
      } catch (Throwable t) {
        LOG.error("Error removing book-keeping reference to allocated memory segment.", t);
      } finally {
        // release the memory in any case
        byte[] buffer = defSeg.destroy();
        this.freeSegments.add(buffer);
      }
    }
    // -------------------- END CRITICAL SECTION -------------------
  }