Re: RE: Transactional Reader Writer Locks

[don . tequila]

Instead of creating a cache with lock objects wouldnБ─≥t it be easier to use a semaphore for each cache where you want to achieve strong reader-Writer consistency? https://ignite.apache.org/docs/latest/data-structures/semaphore Then every time before reading/writing you acquire the semaphore first. I guess this semaphore does essentially what youБ─≥re doing manually. Regards Thomas. On 28.12.21 at 10:41, jay.et...@gmx.de wrote:  And if anyone knows a different way to achieve entire-cache-locks in Optimistic Serializable transactions: We always appreciate the help. Jay     From: Gurmehar Kalra <gurmehar.ka...@hcl.com> Sent: Monday, 27 December 2021 07:31 To: user@ignite.apache.org; alexey.scherbak...@gmail.com Subject: RE: Transactional Reader Writer Locks   Hi, I need to understand when we mean LOCK, is this lock is acquired on entire Cache or on record we are trying to update . Please clarify .   Regards, Gurmehar Singh   From: Alexei Scherbakov <alexey.scherbak...@gmail.com> Sent: 16 December 2021 22:40 To: user <user@ignite.apache.org> Subject: Re: Transactional Reader Writer Locks   [CAUTION: This Email is from outside the Organization. Unless you trust the sender, DonБ─≥t click links or open attachments as it may be a Phishing email, which can steal your Information and compromise your Computer.] Hi.   You can try OPTIMISTIC SERIALIZABLE isolation, it might have better throughput in contending scenarios. But this is not the same as RW lock, because a tx can be invalidated after a commit if a lock conflict is detected. No RW lock of any kind is planned, AFAIK.   п╡я┌, 7 п╢п╣п╨. 2021 пЁ. п╡ 23:22, <jay.et...@gmx.de>: Dear all,   weБ─≥re running in circles with Ignite for so long now. Can anyone please help? All our attempts to custom-build a Reader Writer Lock (/Re-entrant Lock) for use inside transactions have failed.   Background: - Multi-node setup - Very high throughput mixed read/write cache access - Key-Value API using transactional caches - Strong consistency absolute requirement - Transactional context required for guarantees and fault-tolerance   Using Pessimistic Repeatable-Read transactions gives strong consistency but kills performance if thereБ─≥s a large number of operations on the same cache entry (and they tend to introduce performance penalties in entire-cache operations and difficulties in cross-cache locking as well). All other transactional modes somehow violate the strong consistency requirement as we see it and were able to test so far.   In other distributed environments we use reader writer locks to gain both strong consistency and high performance with mixed workloads. In Ignite however weБ─≥re not aware that explicit locks can be used inside transactions: The documentation clearly states so (https://ignite.apache.org/docs/latest/distributed-locks) and trying to custom-build a reader writer lock for use inside transactions we always end up concluding that this may not be achievable if there are multiple ways to implicitly acquire but none to release locks.   Are we out of luck here or - did we miss something? - are there workarounds you know of? - are there plans to implement transactional re-entrant locks in future releases?   Jay       -- Best regards, Alexei Scherbakov ::DISCLAIMER:: The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents (with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates. Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of authorized representative of HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any email and/or attachments, please check them for viruses and other defects.