[ https://issues.jboss.org/browse/ISPN-4018?page=com.atlassian.jira.plugin.... ] Pedro Ruivo commented on ISPN-4018: ----------------------------------- I don't agree with you. If you are going to check all the keys, then you are entering in one-copy serializability (1CS) isolation level. A transaction system is a set of reads and/or writes in a shared state, and we can look in conditional commands as: {code} if (isConditionMet(read(x), expected-value)) { write(x, new-value) } {code} For ISPN (and for me), tx1 should not fail in this scenario (assuming initially x = y): {code} tx1: read(x) //return y tx2: write(x, w) tx1: putIfAbsent(x, z) //no-op since x's value is y {code} and it should fail in this: {code} tx1: read(x) //read y tx2: write(x,w) tx1: putIfAbsent(x,z) //no-op since x's value is y //read(x) will return read y in tx1 tx1: write(x,u) {code} -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira