protected boolean startRemoval() {
    boolean result;
    synchronized (isMarkedForRemovalLock) {
      result = isMarkedForRemoval;
      isMarkedForRemoval = true;
    }
    return result;
  }
Mark the receiver as needing removal

@return true if it was already marked for removal
geode-core/src/main/java/org/apache/geode/internal/cache/tier/sockets/CacheClientProxy.java