Hashtable is overkill for registering transactions. Concurrent HashMap can handle this effectively

[nikhildp]

Reading and writing to tidToTransactionMap_ doesn't have to be synchronised as ConcurrentHashMap is thread safe
In action, this leads to a race condition from multiple threads to register a transaction

transactions-essentials/public/transactions/src/main/java/com/atomikos/icatch/imp/TransactionServiceImp.java

Line 58 in 909422b

private Hashtable<String,CompositeTransaction> tidToTransactionMap_ = null;