Hello! Pavel, I agree with you thorougly. We should be able to multiplex several transactions using a single Client connection. This means adding Transaction id parameter to every affected cache operation / SQL statement (if applicable) to make sure we do cache operations on relevant transaction.
This is how other things work in Ignite, such as communication. We do not open dozens of connections, we multiplex operations asynchronously through a single connection. I think that trying to pool Ignite connections will be highly inconvenient, since there is no existing infrastructure for such pooling (like there exists for JDBC). I want to also ask if "Number of entries participating in transaction (may be approximate). 0 - default value." is needed. Does it actually do anything in our tx protocol? Users of existing APIs are already confused by this parameter, if we could get rid of it in thin client protocol it would be nice clean-up. Regards, -- Ilya Kasnacheev вт, 2 апр. 2019 г. в 09:55, Pavel Tupitsyn <ptupit...@apache.org>: > Alex, > > > now we can only support one active transaction per connection > > I totally understand server-side and protocol limitations that are causing > this. > But I have no idea how to support this in .NET Thin Client, for example. > > It is thread-safe and can handle multiple async operations in parallel. > But with TX support we have to somehow switch to single-threaded mode to > avoid unexpected effects. > > Any ideas? > > > On Mon, Apr 1, 2019 at 6:38 PM Alex Plehanov <plehanov.a...@gmail.com> > wrote: > > > Dmitriy, thank you! > > > > Guys, I've created the IEP [1] on wiki, please have a look. > > > > [1] > > > > > https://cwiki.apache.org/confluence/display/IGNITE/IEP-34+Thin+client%3A+transactions+support > > > > > > чт, 28 мар. 2019 г. в 14:33, Dmitriy Pavlov <dpav...@apache.org>: > > > > > Hi, > > > > > > I've added permissions to account plehanov.alex > > > > > > Recently Infra integrated Apache LDAP with confluence, so it is > possible > > to > > > login using Apache credentials. Probably we can ask infra if extra > > > permissions to edit pages should be added for committers. > > > > > > Sincerely, > > > Dmitriy Pavlov > > > > > > ср, 27 мар. 2019 г. в 13:37, Alex Plehanov <plehanov.a...@gmail.com>: > > > > > > > Vladimir, > > > > > > > > About current tx: ok, then we don't need tx() method in the interface > > at > > > > all (the same cached transaction info user can store by himself). > > > > > > > > About decoupling transactions from threads on the server side: for > now, > > > we > > > > can start with thread-per-connection approach (we only can support > one > > > > active transaction per connection, see below, so we need one > additional > > > > dedicated thread for each connection with active transaction), and > > later > > > > change server-side internals to process client transactions in any > > server > > > > thread (not dedicated to this connection). This change will not > affect > > > the > > > > thin client protocol, it only affects the server side. > > > > In any case, we can't support concurrent transactions per connection > on > > > > the client side without fundamental changes to the current protocol > > > (cache > > > > operation doesn't bound to transaction or thread and the server > doesn't > > > > know which thread on the client side do this cache operation). In my > > > > opinion, if a user wants to use concurrent transactions, he must use > > > > different connections from a connection pool. > > > > > > > > About semantics of suspend/resume on the client-side: it's absolutely > > > > different than server-side semantics (we don't need to do > > suspend/resume > > > to > > > > pass transaction between threads on the client-side), but can't be > > > > implemented efficiently without implemented suspend/resume on > > > server-side. > > > > > > > > Can anyone give me permissions to create IEP on Apache wiki? > > > > > > > > ср, 27 мар. 2019 г. в 11:59, Vladimir Ozerov <voze...@gridgain.com>: > > > > > > > > > Hi Alex, > > > > > > > > > > My comments was only about the protocol. Getting current info about > > > > > transaction should be handled by the client itself. It is not > > protocl's > > > > > concern. Same about other APIs and behavior in case another > > transaction > > > > is > > > > > attempted from the same thread. > > > > > > > > > > Putting protocol aside, transaction support is complicated matter. > I > > > > would > > > > > propose to route through IEP and wide community discussion. We need > > to > > > > > review API and semantics very carefully, taking SUSPEND/RESUME in > > > count. > > > > > Also I do not see how we support client transactions efficiently > > > without > > > > > decoupling transactions from threads on the server side first. > > Because > > > > > without it you will need a dedicated server thread for every > client's > > > > > transaction which is slow and may even crash the server. > > > > > > > > > > Vladimir. > > > > > > > > > > On Wed, Mar 27, 2019 at 11:44 AM Alex Plehanov < > > > plehanov.a...@gmail.com> > > > > > wrote: > > > > > > > > > > > Vladimir, what if we want to get current transaction info (tx() > > > > method)? > > > > > > > > > > > > Does close() method mapped to TX_END(rollback)? > > > > > > > > > > > > For example, this code: > > > > > > > > > > > > try(tx = txStart()) { > > > > > > tx.commit(); > > > > > > } > > > > > > > > > > > > Will produce: > > > > > > TX_START > > > > > > TX_END(commit) > > > > > > TX_END(rollback) > > > > > > > > > > > > Am I understand you right? > > > > > > > > > > > > About xid. There is yet another proposal. Use some unique per > > > > connection > > > > > id > > > > > > (integer, simple counter) for identifying the transaction on > > > > > > commit/rollback message. The client gets this id from the server > > with > > > > > > transaction info and sends it back to the server when trying to > > > > > > commit/rollback transaction. This id is not shown to users. But > > also > > > we > > > > > can > > > > > > pass from server to client real transaction id (xid) with > > transaction > > > > > info > > > > > > for diagnostic purposes. > > > > > > > > > > > > And one more question: what should we do if the client starts a > new > > > > > > transaction without ending the old one? Should we end the old > > > > transaction > > > > > > implicitly (rollback) or throw an exception to the client? In my > > > > opinion, > > > > > > the first option is better. For example, if we got a previously > > used > > > > > > connection from the connection pool, we should not worry about > any > > > > > > uncompleted transaction started by the previous user of this > > > > connection. > > > > > > > > > > > > ср, 27 мар. 2019 г. в 11:02, Vladimir Ozerov < > voze...@gridgain.com > > >: > > > > > > > > > > > > > As far as SUSPEND/RESUME/SAVEPOINT - we do not support them > yet, > > > and > > > > > > adding > > > > > > > them in future should not conflict with simple START/END > > > > > infrastructure. > > > > > > > > > > > > > > On Wed, Mar 27, 2019 at 11:00 AM Vladimir Ozerov < > > > > voze...@gridgain.com > > > > > > > > > > > > > wrote: > > > > > > > > > > > > > > > Hi Alex, > > > > > > > > > > > > > > > > I am not sure we need 5 commands. Wouldn't it be enough to > have > > > > only > > > > > > two? > > > > > > > > > > > > > > > > START - accepts optional parameters, returns transaction info > > > > > > > > END - provides commit flag, returns void > > > > > > > > > > > > > > > > Vladimir. > > > > > > > > > > > > > > > > On Wed, Mar 27, 2019 at 8:26 AM Alex Plehanov < > > > > > plehanov.a...@gmail.com > > > > > > > > > > > > > > > wrote: > > > > > > > > > > > > > > > >> Sergey, yes, the close is something like silent rollback. > But > > we > > > > can > > > > > > > >> also implement this on the client side, just using rollback > > and > > > > > > ignoring > > > > > > > >> errors in the response. > > > > > > > >> > > > > > > > >> ср, 27 мар. 2019 г. в 00:04, Sergey Kozlov < > > > skoz...@gridgain.com > > > > >: > > > > > > > >> > > > > > > > >> > Nikolay > > > > > > > >> > > > > > > > > >> > Am I correctly understand you points: > > > > > > > >> > > > > > > > > >> > - close: rollback > > > > > > > >> > - commit, close: do nothing > > > > > > > >> > - rollback, close: do what? (I suppose nothing) > > > > > > > >> > > > > > > > > >> > Also you assume that after commit/rollback we may need to > > free > > > > > some > > > > > > > >> > resources on server node(s)or just do on client started > TX? > > > > > > > >> > > > > > > > > >> > > > > > > > > >> > > > > > > > > >> > On Tue, Mar 26, 2019 at 10:41 PM Alex Plehanov < > > > > > > > plehanov.a...@gmail.com > > > > > > > >> > > > > > > > > >> > wrote: > > > > > > > >> > > > > > > > > >> > > Sergey, we have the close() method in the thick client, > > it's > > > > > > > behavior > > > > > > > >> is > > > > > > > >> > > slightly different than rollback() method (it should > > > rollback > > > > if > > > > > > the > > > > > > > >> > > transaction is not committed and do nothing if the > > > transaction > > > > > is > > > > > > > >> already > > > > > > > >> > > committed). I think we should support try-with-resource > > > > > semantics > > > > > > in > > > > > > > >> the > > > > > > > >> > > thin client and OP_TX_CLOSE will be useful here. > > > > > > > >> > > > > > > > > > >> > > Nikolay, suspend/resume didn't work yet for pessimistic > > > > > > > transactions. > > > > > > > >> > Also, > > > > > > > >> > > the main goal of suspend/resume operations is to support > > > > > > transaction > > > > > > > >> > > passing between threads. In the thin client, the > > transaction > > > > is > > > > > > > bound > > > > > > > >> to > > > > > > > >> > > the client connection, not client thread. I think > passing > > a > > > > > > > >> transaction > > > > > > > >> > > between different client connections is not a very > useful > > > > case. > > > > > > > >> > > > > > > > > > >> > > вт, 26 мар. 2019 г. в 22:17, Nikolay Izhikov < > > > > > nizhi...@apache.org > > > > > > >: > > > > > > > >> > > > > > > > > > >> > > > Hello, Alex. > > > > > > > >> > > > > > > > > > > >> > > > We also have suspend and resume operations. > > > > > > > >> > > > I think we should support them > > > > > > > >> > > > > > > > > > > >> > > > вт, 26 марта 2019 г., 22:07 Sergey Kozlov < > > > > > skoz...@gridgain.com > > > > > > >: > > > > > > > >> > > > > > > > > > > >> > > > > Hi > > > > > > > >> > > > > > > > > > > > >> > > > > Looks like I missed something but why we need > > > OP_TX_CLOSE > > > > > > > >> operation? > > > > > > > >> > > > > > > > > > > > >> > > > > Also I suggest to reserve a code for SAVEPOINT > > operation > > > > > which > > > > > > > >> very > > > > > > > >> > > > useful > > > > > > > >> > > > > to understand where transaction has been rolled back > > > > > > > >> > > > > > > > > > > > >> > > > > On Tue, Mar 26, 2019 at 6:07 PM Alex Plehanov < > > > > > > > >> > plehanov.a...@gmail.com > > > > > > > >> > > > > > > > > > > >> > > > > wrote: > > > > > > > >> > > > > > > > > > > > >> > > > > > Hello Igniters! > > > > > > > >> > > > > > > > > > > > > >> > > > > > I want to pick up the ticket IGNITE-7369 and add > > > > > > transactions > > > > > > > >> > support > > > > > > > >> > > > to > > > > > > > >> > > > > > our thin client implementation. > > > > > > > >> > > > > > I've looked at our current implementation and have > > > some > > > > > > > >> proposals > > > > > > > >> > to > > > > > > > >> > > > > > support transactions: > > > > > > > >> > > > > > > > > > > > > >> > > > > > Add new operations to thin client protocol: > > > > > > > >> > > > > > > > > > > > > >> > > > > > OP_TX_GET, 4000, Get current transaction for > > > client > > > > > > > >> connection > > > > > > > >> > > > > > OP_TX_START, 4001, Start a new transaction > > > > > > > >> > > > > > OP_TX_COMMIT, 4002, Commit transaction > > > > > > > >> > > > > > OP_TX_ROLLBACK, 4003, Rollback transaction > > > > > > > >> > > > > > OP_TX_CLOSE, 4004, Close transaction > > > > > > > >> > > > > > > > > > > > > >> > > > > > From the client side (java) new interfaces will be > > > > added: > > > > > > > >> > > > > > > > > > > > > >> > > > > > public interface ClientTransactions { > > > > > > > >> > > > > > public ClientTransaction txStart(); > > > > > > > >> > > > > > public ClientTransaction > > > > > txStart(TransactionConcurrency > > > > > > > >> > > > concurrency, > > > > > > > >> > > > > > TransactionIsolation isolation); > > > > > > > >> > > > > > public ClientTransaction > > > > > txStart(TransactionConcurrency > > > > > > > >> > > > concurrency, > > > > > > > >> > > > > > TransactionIsolation isolation, long timeout, int > > > > txSize); > > > > > > > >> > > > > > public ClientTransaction tx(); // Get current > > > > > connection > > > > > > > >> > > > transaction > > > > > > > >> > > > > > public ClientTransactions withLabel(String > lb); > > > > > > > >> > > > > > } > > > > > > > >> > > > > > > > > > > > > >> > > > > > public interface ClientTransaction extends > > > > AutoCloseable { > > > > > > > >> > > > > > public IgniteUuid xid(); // Do we need it? > > > > > > > >> > > > > > public TransactionIsolation isolation(); > > > > > > > >> > > > > > public TransactionConcurrency concurrency(); > > > > > > > >> > > > > > public long timeout(); > > > > > > > >> > > > > > public String label(); > > > > > > > >> > > > > > > > > > > > > >> > > > > > public void commit(); > > > > > > > >> > > > > > public void rollback(); > > > > > > > >> > > > > > public void close(); > > > > > > > >> > > > > > } > > > > > > > >> > > > > > > > > > > > > >> > > > > > From the server side, I think as a first step > (while > > > > > > > >> transactions > > > > > > > >> > > > > > suspend/resume is not fully implemented) we can > use > > > the > > > > > same > > > > > > > >> > approach > > > > > > > >> > > > as > > > > > > > >> > > > > > for JDBC: add a new worker to each > > > ClientRequestHandler > > > > > and > > > > > > > >> process > > > > > > > >> > > > > > requests by this worker if the transaction is > > started > > > > > > > >> explicitly. > > > > > > > >> > > > > > ClientRequestHandler is bound to client > connection, > > so > > > > > there > > > > > > > >> will > > > > > > > >> > be > > > > > > > >> > > > 1:1 > > > > > > > >> > > > > > relation between client connection and thread, > which > > > > > process > > > > > > > >> > > operations > > > > > > > >> > > > > in > > > > > > > >> > > > > > a transaction. > > > > > > > >> > > > > > > > > > > > > >> > > > > > Also, there is a couple of issues I want to > discuss: > > > > > > > >> > > > > > > > > > > > > >> > > > > > We have overloaded method txStart with a different > > set > > > > of > > > > > > > >> > arguments. > > > > > > > >> > > > Some > > > > > > > >> > > > > > of the arguments may be missing. To pass arguments > > > with > > > > > > > >> OP_TX_START > > > > > > > >> > > > > > operation we have the next options: > > > > > > > >> > > > > > * Serialize full set of arguments and use some > > value > > > > for > > > > > > > >> missing > > > > > > > >> > > > > > arguments. For example -1 for int/long types and > > null > > > > for > > > > > > > string > > > > > > > >> > > type. > > > > > > > >> > > > We > > > > > > > >> > > > > > can't use 0 for int/long types since 0 it's a > valid > > > > value > > > > > > for > > > > > > > >> > > > > concurrency, > > > > > > > >> > > > > > isolation and timeout arguments. > > > > > > > >> > > > > > * Serialize arguments as a collection of > > > property-value > > > > > > pairs > > > > > > > >> > (like > > > > > > > >> > > > it's > > > > > > > >> > > > > > implemented now for CacheConfiguration). In this > > case > > > > only > > > > > > > >> > explicitly > > > > > > > >> > > > > > provided arguments will be serialized. > > > > > > > >> > > > > > Which way is better? The simplest solution is to > use > > > the > > > > > > first > > > > > > > >> > option > > > > > > > >> > > > > and I > > > > > > > >> > > > > > want to use it if there were no objections. > > > > > > > >> > > > > > > > > > > > > >> > > > > > Do we need transaction id (xid) on the client > side? > > > > > > > >> > > > > > If yes, we can pass xid along with OP_TX_COMMIT, > > > > > > > OP_TX_ROLLBACK, > > > > > > > >> > > > > > OP_TX_CLOSE operations back to the server and do > > > > > additional > > > > > > > >> check > > > > > > > >> > on > > > > > > > >> > > > the > > > > > > > >> > > > > > server side (current transaction id for connection > > == > > > > > > > >> transaction > > > > > > > >> > id > > > > > > > >> > > > > passed > > > > > > > >> > > > > > from client side). This, perhaps, will protect > > clients > > > > > > against > > > > > > > >> some > > > > > > > >> > > > > errors > > > > > > > >> > > > > > (for example when client try to commit outdated > > > > > > transaction). > > > > > > > >> But > > > > > > > >> > > > > > currently, we don't have data type IgniteUuid in > > thin > > > > > client > > > > > > > >> > > protocol. > > > > > > > >> > > > Do > > > > > > > >> > > > > > we need to add it too? > > > > > > > >> > > > > > Also, we can pass xid as a string just to inform > the > > > > > client > > > > > > > and > > > > > > > >> do > > > > > > > >> > > not > > > > > > > >> > > > > pass > > > > > > > >> > > > > > it back to the server with commit/rollback > > operation. > > > > > > > >> > > > > > Or not to pass xid at all (.NET thick client works > > > this > > > > > way > > > > > > as > > > > > > > >> far > > > > > > > >> > > as I > > > > > > > >> > > > > > know). > > > > > > > >> > > > > > > > > > > > > >> > > > > > What do you think? > > > > > > > >> > > > > > > > > > > > > >> > > > > > ср, 7 мар. 2018 г. в 16:22, Vladimir Ozerov < > > > > > > > >> voze...@gridgain.com > > > > > > > >> > >: > > > > > > > >> > > > > > > > > > > > > >> > > > > > > We already have transactions support in JDBC > > driver > > > in > > > > > TX > > > > > > > SQL > > > > > > > >> > > branch > > > > > > > >> > > > > > > (ignite-4191). Currently it is implemented > through > > > > > > separate > > > > > > > >> > thread, > > > > > > > >> > > > > which > > > > > > > >> > > > > > > is not that efficient. Ideally we need to finish > > > > > > decoupling > > > > > > > >> > > > > transactions > > > > > > > >> > > > > > > from threads. But alternatively we can change > the > > > > logic > > > > > on > > > > > > > >> how we > > > > > > > >> > > > > assign > > > > > > > >> > > > > > > thread ID to specific transaction and > > "impersonate" > > > > thin > > > > > > > >> client > > > > > > > >> > > > worker > > > > > > > >> > > > > > > threads when serving requests from multiple > users. > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > On Tue, Mar 6, 2018 at 10:01 PM, Denis Magda < > > > > > > > >> dma...@apache.org> > > > > > > > >> > > > > wrote: > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > Here is an original discussion with a > reference > > to > > > > the > > > > > > > JIRA > > > > > > > >> > > ticket: > > > > > > > >> > > > > > > > > > http://apache-ignite-developers.2346864.n4.nabble > > > . > > > > > > > >> > > > > > > > > > > > > > > com/Re-Transaction-operations-using-the-Ignite-Thin-Client- > > > > > > > >> > > > > > > > Protocol-td25914.html > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > > > -- > > > > > > > >> > > > > > > > Denis > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > > > On Tue, Mar 6, 2018 at 9:18 AM, Dmitriy > > Setrakyan > > > < > > > > > > > >> > > > > > dsetrak...@apache.org > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > > > wrote: > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > > > > Hi Dmitriy. I don't think we have a design > > > > proposal > > > > > > for > > > > > > > >> > > > transaction > > > > > > > >> > > > > > > > support > > > > > > > >> > > > > > > > > in thin clients. Do you mind taking this > > > > initiative > > > > > > and > > > > > > > >> > > creating > > > > > > > >> > > > an > > > > > > > >> > > > > > IEP > > > > > > > >> > > > > > > > on > > > > > > > >> > > > > > > > > Wiki? > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > > > > D. > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > > > > On Tue, Mar 6, 2018 at 8:46 AM, Dmitriy > > > > Govorukhin < > > > > > > > >> > > > > > > > > dmitriy.govoruk...@gmail.com> wrote: > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > Hi, Igniters. > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > I've seen a lot of discussions about thin > > > client > > > > > and > > > > > > > >> binary > > > > > > > >> > > > > > protocol, > > > > > > > >> > > > > > > > > but I > > > > > > > >> > > > > > > > > > did not hear anything about transactions > > > > support. > > > > > Do > > > > > > > we > > > > > > > >> > have > > > > > > > >> > > > some > > > > > > > >> > > > > > > draft > > > > > > > >> > > > > > > > > for > > > > > > > >> > > > > > > > > > this purpose? > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > As I understand we have several problems: > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > - thread and transaction have hard > > related > > > > (we > > > > > > use > > > > > > > >> > > > > thread-local > > > > > > > >> > > > > > > > > variable > > > > > > > >> > > > > > > > > > and thread name) > > > > > > > >> > > > > > > > > > - we can process only one transaction > at > > > the > > > > > same > > > > > > > >> time > > > > > > > >> > in > > > > > > > >> > > > one > > > > > > > >> > > > > > > thread > > > > > > > >> > > > > > > > > (it > > > > > > > >> > > > > > > > > > mean we need hold thread per client. If > > > > connect > > > > > > 100 > > > > > > > >> thin > > > > > > > >> > > > > clients > > > > > > > >> > > > > > > to > > > > > > > >> > > > > > > > 1 > > > > > > > >> > > > > > > > > > server node, then need to hold 100 > thread > > > on > > > > > the > > > > > > > >> server > > > > > > > >> > > > side) > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > Let's discuss how we can implement > > > transactions > > > > > for > > > > > > > the > > > > > > > >> > thin > > > > > > > >> > > > > > client. > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > >> > > > > > > > > > > > >> > > > > > > > > > > > >> > > > > -- > > > > > > > >> > > > > Sergey Kozlov > > > > > > > >> > > > > GridGain Systems > > > > > > > >> > > > > www.gridgain.com > > > > > > > >> > > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > >> > > > > > > > > >> > -- > > > > > > > >> > Sergey Kozlov > > > > > > > >> > GridGain Systems > > > > > > > >> > www.gridgain.com > > > > > > > >> > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
