@Override
  public boolean exists(TransactionId transactionId) {
    return isHostedTxInProgress((TXId) transactionId) || isSuspended(transactionId)
        || localTxMap.containsKey(transactionId);
  }
this map keeps track of all the threads that are waiting in
{@link #tryResume(TransactionId, long, TimeUnit)} for a particular transactionId
geode-core/src/main/java/org/apache/geode/internal/cache/TXManagerImpl.java