Hello, Alexey. Could you please, write little more about your implementation
1. Design of implementation. 2. Advantages of you implementation in compare with other ways? 3. Transactions performance penalties/improvements? В Вт, 13/02/2018 в 14:17 +0000, ALEKSEY KUZNETSOV пишет: > Hi, Igniters! > > Currently we have context switching implemented for optimistic > transactions [1]. > > Goal of the current ticket is to support transaction suspend()\resume() > operations for pessimistic transactions. > > The essential problem with them lies in *IgniteTxAdapter#threadId*. > Thread id is set when transaction is created and afterwards is transferred > between nodes by GridDistributedTx requests\responses when we perform > put\get operations. > When we suspend and resume transaction, thread id is got changed locally, > but not on remote nodes. > > In ticket I decided to partly remove thread id from source, and introduced > *undefined* value for it, where its value must be ignored. > Another solution can be to replace thread id usage with some new global > transaction id counter. > > The former solution has advantages : > compatibility is preserved, step-by-step clear implementation, minimal > changes to explicit cache lock work(it still creates candidates with > not-null thread id) as opposed to the last solution. > > There are 3 possible solutions to "thread id on remote nodes" issue : > 1) Change thread id on remote nodes once suspend()\resume() is called. > 2) Get rid of sending thread id to remote nodes. > 3) Don’t remove the field, just put -1 (undefined) in it. > > The last option was chosen, because it will save compatibility in cluster > with nodes of older versions. > Note that still outside the transaction, when explicit cache lock is > created, thread id is set not null value in lock request(i.e. > GridNearLockRequest). > > Thread id is moved from global IgniteTxAdapter to GridNearTxLocal, as long > as only *near local* transaction is need it. > For instance, when local candidate(either near local or dht local) is > created for GridNearTxLocal. Note that remote candidates are created with > thread id undefined, because it useless for non-local candidates. > In IgniteTxAdapter#ownsLock thread id is replaced with tx version check. > We could do it, because near transactions has got unique versions to check > against. > > In tx synchronizer GridCacheTxFinishSync thread id is replaced with tx > version, so we don't need to store it and send by GridFinishResponse > messages. > As a consequence, thread id is also removed from grid near finish\prepare > request\response. > > Also, thread id information is removed from deadlock messages (in > TxDeadlock, TxDeadlockDetection). > > Please, review it: > > ticket *https://issues.apache.org/jira/browse/IGNITE-5714 > <https://issues.apache.org/jira/browse/IGNITE-5714>* > pull request *https://github.com/apache/ignite/pull/2789 > <https://github.com/apache/ignite/pull/2789>* > review https://reviews.ignite.apache.org/ignite/review/IGNT-CR-364 > > [1] : https://issues.apache.org/jira/browse/IGNITE-5712.
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