It seems like it is worthwhile to brush up my knowledge then, this looks quite hopeful - thanks!
On 24 February 2015 at 10:39, Andrey Antukh <n...@niwi.be> wrote: > > > 2015-02-24 10:15 GMT+01:00 Colin Yates <colin.ya...@gmail.com>: >> >> Hi Andrey - thanks for responding. Asciidoctor looks great! >> >> I think I understand the sucriata approach which serialises access to >> the connection (via the agent). But this doesn't ensure that all >> operations using the connection are done in the same thread does it (I >> didn't think agents were thread-locked)?. In not then it looks like a >> no go. > > > Yes, the agent does not ensures that all operations using a connection are > done in the same thread. Using agent only ensures that all actions > are done in serialized way and only one thread uses the connection at time. >> >> >> To be clear, my understanding (which is from a while ago admittedly) >> is that JDBC transaction implementations tend to use thread locals to >> store a bunch of stuff so it isn't so much the concurrent access which >> is a problem (nicely solved by the agent approach) it is ensuring it >> is ensuring the same thread is used. > > > I'm not expert in jdbc, but I have see the source of postgresql jdbc, and > the transaction state is bind to the connection, nothing related > to thread locals. > > Thread locals are often used for "transaction mangers" like spring tx, maybe > hibernate (I'm not sure because I have never used it), and other lightweight > implementations like that https://github.com/witoldsz/ultm ... > > But in case of plain jdbc transactions, as far as I know, no thread local > state is involved. > > Cheers. > Andrey > >> >> >> On 23 February 2015 at 23:41, Andrey Antukh <n...@niwi.be> wrote: >> > Hi Colin. >> > >> > You are talking about suricatta documentation? Is build with >> > asciidoctor. >> > >> > And, about core.async and transactions, suricatta comes with an async >> > abstraction that internally uses a clojure agent for serialize all >> > access to >> > one connection from different threads (managed by core.async internal >> > thread >> > pool). Nothing special is used from jooq for handle it. >> > >> > A suricatta context encapsulates the standard jdbc connection and >> > additional >> > state. As far as I know, JDBC connection is not fully thread safe >> > >> > (http://stackoverflow.com/questions/1531073/is-java-sql-connection-thread-safe), >> > and the general opinion is avoid use the same connection instance from >> > different threads concurrently. But the suricata approach is share a >> > connection instance between threads but ensuring that only one thread >> > can >> > use it at same time (as I said previously) using serialization semantics >> > of >> > clojure agents. >> > >> > I hope it has been helpful. >> > >> > Cheers >> > Andrey >> > >> > >> > 2015-02-23 22:26 GMT+01:00 Colin Yates <colin.ya...@gmail.com>: >> >> >> >> Thanks Christian, that looks interesting. >> >> >> >> By the way, any idea what tool was used to generate the documentation? >> >> >> >> On 23 February 2015 at 21:22, Christian Weilbach >> >> <whitesp...@polyc0l0r.net> wrote: >> >> > -----BEGIN PGP SIGNED MESSAGE----- >> >> > Hash: SHA1 >> >> > >> >> > On 23.02.2015 18:20, Colin Yates wrote: >> >> >> Currently each request gets serviced in its own thread (web >> >> >> container) and I am thinking of integrating core.async and I wonder >> >> >> how core.async and a JDBC transactional "unit of work" get on. >> >> >> >> >> >> Conceptually, this model (thread-per-request) is trivial however >> >> >> the problems are well known. Replacing this with core.async right >> >> >> at the front is trivial but I can see the benefit of sprinkling >> >> >> asynchronous behaviour throughout the (still very trivial) >> >> >> pipeline. Or rather I can see the beauty of decomposed components >> >> >> communicating via channels. >> >> >> >> >> >> My question is about transactionality. I am used to JDBC >> >> >> transactions being thread local and I understand core.async >> >> >> utilises a thread-pool, so how does one implement a "unit of work" >> >> >> that spans multiple channels? >> >> >> >> >> >> I want to do something like: >> >> >> >> >> >> - request comes in - the appropriate handler/service consumes it >> >> >> (either through request mapping, defmethod whatever) - TX starts - >> >> >> in parallel some logging happens (and DB is updated) - the message >> >> >> is handled (and DB is updated) - performance metrics are stored >> >> >> (and DB is updated) - all work on all channels gets finished - TX >> >> >> commits >> >> >> >> >> >> The point is that channels are used only to communicate between >> >> >> disconnected components but they should all participate in the same >> >> >> TX. >> >> >> >> >> >> Is anyone else using channels like this? >> >> > I have done it in IndexedDB in JavaScript and had to use the proper >> >> > callback API (1), because otherwise transactions break. I guess you >> >> > cannot do channel operations inside a JDBC operation since they are >> >> > executed in the threadpool (by the state-machine) while each JDBC >> >> > connection seems to be pinned to a thread, so you cannot participate >> >> > in the same transaction from another thread of the threadpool. But if >> >> > you can wrap your blocking JDBC stuff in a singular thread call, you >> >> > might be able to use async/thread (probably less than you want). >> >> > >> >> > There is also https://github.com/niwibe/suricatta, but I have no >> >> > experience with it. jooq seems to solve the the thread per request >> >> > problem decoupling into async operations you have in mind. >> >> > >> >> > Cheers, >> >> > Christian >> >> > >> >> > (1) >> >> > >> >> > >> >> > https://github.com/ghubber/konserve/blob/master/src/cljs/konserve/indexeddb.cljs >> >> > -----BEGIN PGP SIGNATURE----- >> >> > Version: GnuPG v1 >> >> > >> >> > iQEcBAEBAgAGBQJU65n6AAoJEKel+aujRZMkwaAH/1Eq2/vr84WqNq6u2rcG4ly+ >> >> > xkByy602oMy9/ScK1/ytv/kFdPG+qAYmtQ4EHq/LGUma3zLjpPdrf49A1RUGfVii >> >> > fbwIUiRgUJWdigrGiSf/2zIn972MgIfc4qKFj/+/2hJNZIAwlAKiPQSvG2VPrHo7 >> >> > dskeQZeCZI4yGSz4+dQFGmKvjiAum+UConkzn0T/N2XGknerFsLonXyvpbTv/SCC >> >> > NwNoRJzI39kjIyhfUuwbwHoy0/DtbxjvkbrLHeyGIKGOJ75QutWY6gvkRsSlzS5g >> >> > A2jVtZo/hw02di3mxrD1vwSZ2PWads2juKjCmmOQrIPofSBWyVmoGeQ/qyD/Dgw= >> >> > =Wi7E >> >> > -----END PGP SIGNATURE----- >> >> > >> >> > -- >> >> > You received this message because you are subscribed to the Google >> >> > Groups "Clojure" group. >> >> > To post to this group, send email to clojure@googlegroups.com >> >> > Note that posts from new members are moderated - please be patient >> >> > with >> >> > your first post. >> >> > To unsubscribe from this group, send email to >> >> > clojure+unsubscr...@googlegroups.com >> >> > For more options, visit this group at >> >> > http://groups.google.com/group/clojure?hl=en >> >> > --- >> >> > You received this message because you are subscribed to the Google >> >> > Groups "Clojure" group. >> >> > To unsubscribe from this group and stop receiving emails from it, >> >> > send >> >> > an email to clojure+unsubscr...@googlegroups.com. >> >> > For more options, visit https://groups.google.com/d/optout. >> >> >> >> -- >> >> You received this message because you are subscribed to the Google >> >> Groups "Clojure" group. >> >> To post to this group, send email to clojure@googlegroups.com >> >> Note that posts from new members are moderated - please be patient with >> >> your first post. >> >> To unsubscribe from this group, send email to >> >> clojure+unsubscr...@googlegroups.com >> >> For more options, visit this group at >> >> http://groups.google.com/group/clojure?hl=en >> >> --- >> >> You received this message because you are subscribed to the Google >> >> Groups >> >> "Clojure" group. >> >> To unsubscribe from this group and stop receiving emails from it, send >> >> an >> >> email to clojure+unsubscr...@googlegroups.com. >> >> For more options, visit https://groups.google.com/d/optout. >> > >> > >> > >> > >> > -- >> > Andrey Antukh - Андрей Антух - <andrei.anto...@kaleidos.net> / >> > <n...@niwi.be> >> > http://www.niwi.be >> > https://github.com/niwibe >> > >> > -- >> > You received this message because you are subscribed to the Google >> > Groups "Clojure" group. >> > To post to this group, send email to clojure@googlegroups.com >> > Note that posts from new members are moderated - please be patient with >> > your >> > first post. >> > To unsubscribe from this group, send email to >> > clojure+unsubscr...@googlegroups.com >> > For more options, visit this group at >> > http://groups.google.com/group/clojure?hl=en >> > --- >> > You received this message because you are subscribed to the Google >> > Groups >> > "Clojure" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> > an >> > email to clojure+unsubscr...@googlegroups.com. >> > For more options, visit https://groups.google.com/d/optout. >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clojure@googlegroups.com >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clojure+unsubscr...@googlegroups.com >> For more options, visit this group at >> http://groups.google.com/group/clojure?hl=en >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. > > > > > -- > Andrey Antukh - Андрей Антух - <andrei.anto...@kaleidos.net> / > <n...@niwi.be> > http://www.niwi.be > https://github.com/niwibe > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with your > first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
