Lock is put by cache adapter. Now its clear
пн, 3 июл. 2017 г. в 15:14, ALEKSEY KUZNETSOV <alkuznetsov...@gmail.com>:
> Consider thread *Th1* started transaction *Tx1*, done some actions, and
> is calling commit (GridNearTxLocal#commit -> commitNearTxLocalAsync). And
> concurrently thread *Th2 *is calling the same commit on* Tx1*. Now, if
> you look into code :
>
> public IgniteInternalFuture<IgniteInternalTx> commitNearTxLocalAsync() {
> if (log.isDebugEnabled())
> log.debug("Committing near local tx: " + this);
>
> if (fastFinish()) {
> state(PREPARING);
> state(PREPARED);
> state(COMMITTING);
>
> cctx.tm().fastFinishTx(this, true);
>
> state(COMMITTED);
>
> return new GridFinishedFuture<>((IgniteInternalTx)this);
> }
>
> final IgniteInternalFuture<?> prepareFut = prepareNearTxLocal();//1
>
> GridNearTxFinishFuture fut = commitFut;
>
> if (fut == null &&
> !COMMIT_FUT_UPD.compareAndSet(this, null, fut = new
> GridNearTxFinishFuture<>(cctx, this, true)))
> return commitFut;//2
>
> cctx.mvcc().addFuture(fut, fut.futureId());//3
>
> Both threads would end up on //1 .Then.
> *Th1 *would create *commitFut* in //2 and add it to mvcc //3
> *Th2 *concurrently would evaluate //2 into true(it sees fut not null now)
> and put fut into mvcc //3 which would lead to exception.
>
> So, there is no locking sections (mutex) here
>
> ---------- Forwarded message ---------
> From: Yakov Zhdanov <yzhda...@apache.org>
> Date: пн, 3 июл. 2017 г. в 14:16
> Subject: Re: Support for starting transaction in another thread IGNITE-4887
> To: ALEKSEY KUZNETSOV <alkuznetsov...@gmail.com>
>
>
> Alex, what do you mean by "multiple threads committing?". Transaction
> should be committed only by one thread and only once.
>
> Can you please provide a test or a code snippet to demonstrate the issue
> you mentioned.
>
>
> --Yakov
>
>
>
>
> Im looking into current implementation of commitNearTxLocalAsync() , and
> in case of multiple concurrent threads committing there would be exception
> thrown by
>
> cctx.mvcc().addFuture(fut, fut.futureId());
>
> Is it correct behavior ?
>
> --
>
> *Best Regards,*
>
> *Kuznetsov Aleksey*
>
--
*Best Regards,*
*Kuznetsov Aleksey*
