From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Amirouche Boubekki Newsgroups: gmane.comp.gnu.guix.user,gmane.lisp.guile.user Subject: Re: Introducing GNUPaste (and guile-wiredtiger future) Date: Sun, 17 Dec 2017 15:39:52 +0100 Message-ID: <11c569c155672a6da5fce60c67b358f4@hypermove.net> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Trace: blaine.gmane.org 1513521504 28031 195.159.176.226 (17 Dec 2017 14:38:24 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 17 Dec 2017 14:38:24 +0000 (UTC) User-Agent: Roundcube Webmail/1.1.2 Cc: Andy Wingo , guile-user@gnu.org, help-guix@gnu.org, Help-Guix To: Kristofer Buffington Original-X-From: help-guix-bounces+gcggh-help-guix=m.gmane.org@gnu.org Sun Dec 17 15:38:20 2017 Return-path: Envelope-to: gcggh-help-guix@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1eQa55-0006tA-HE for gcggh-help-guix@m.gmane.org; Sun, 17 Dec 2017 15:38:19 +0100 Original-Received: from localhost ([::1]:54483 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eQa72-0000eH-2p for gcggh-help-guix@m.gmane.org; Sun, 17 Dec 2017 09:40:20 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:51683) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eQa6l-0000ca-PE for help-guix@gnu.org; Sun, 17 Dec 2017 09:40:04 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eQa6k-0003NQ-GM for help-guix@gnu.org; Sun, 17 Dec 2017 09:40:03 -0500 Original-Received: from relay3-d.mail.gandi.net ([2001:4b98:c:538::195]:33286) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eQa6e-0003GL-Jg; Sun, 17 Dec 2017 09:39:56 -0500 Original-Received: from webmail.gandi.net (webmail9-d.mgt.gandi.net [10.58.1.149]) (Authenticated sender: amirouche@hypermove.net) by relay3-d.mail.gandi.net (Postfix) with ESMTPA id D435FA80CD; Sun, 17 Dec 2017 15:39:52 +0100 (CET) X-Sender: amirouche@hypermove.net X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2001:4b98:c:538::195 X-BeenThere: help-guix@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-guix-bounces+gcggh-help-guix=m.gmane.org@gnu.org Original-Sender: "Help-Guix" Xref: news.gmane.org gmane.comp.gnu.guix.user:2776 gmane.lisp.guile.user:14378 Archived-At: Héllo, On 2017-12-14 19:37, Kristofer Buffington wrote: > Hello! > > I am excited to share GNUPaste! This is a really simple web app > similar to paste.lisp.org built with Guile. I have a linode running it > from git on GuixSD. > > https://paste.freshbakedyams.com (Please use it!) > Source: https://github.com/kristoferbuffington/gnupaste.git > > Currently the frontend uses twitter bootstrap + jquery and highlightjs > from a CDN. It really doesn't need all that boilerplate. It will > definitely change in the future. GNUPaste depends on guile-wiredtiger > and guile-fibers to compile. Thanks for considering guile-wiredtiger. Basically, guile-wiredtiger is not compatible yet with fiber in the general case, because fiber will spawn several threads and several fibers in each thread (and I think that fibers can be stolen by other threads but I am not sure). The way wiredtiger works is that there is one *connexion* (called *environment* in guile wiredtiger) per database and one *session* per "thread" of execution (called *context* in guile wiredtiger). I changed the naming because they are different from the original things. Both environment and context are backed by fluids. In a pre-fork thread model, one must use with-context [1] after the fork to populate the current fuild with a specific context. [1] https://framagit.org/a-guile-mind/guile-wiredtiger/blob/master/wiredtiger/extra.scm#L328 The thing is that when using fibers, the thread of execution is a fiber, hence simply said the wiredtiger extra abstraction called context fails. Because context/session must not be shared between different fibers even if they are executed in the same thread. Otherwise said, guile-wiredtiger extra abstraction context and environment are handy in single thread context because it avoids passing the context around. It's also handy in simple multithread settings where you don't need to pass environment around (to create a new session per thread). But it fails in the advanced use case of guile fibers. This won't trigger a crash under low traffic, but will fail under load and advanced use of guile wiredtiger, like multiple statments transactions. This can be mitigated by turning off preemption in guile-fibers but again it's not perfect solution. I failed to create an API that makes simple things simple and complex things possible. There might be an escape if fibers implemented fluids for fibers something like PEP 550 [2]. But anyway, it won't be perfect, so I will rework the current databases in guile wiredtiger to completly avoid the use of fluids and instead pass around database cnx and session. [2] https://www.python.org/dev/peps/pep-0550/ I started doing this in culturia [3] but it's far from being complete. Since I need to convert all databases grf3, feature-space and ix to that style. Also, it's a backward incompatible change. [3] https://github.com/a-guile-mind/culturia.one/commit/15328e53fcb51d43f14de2f9f21d0b309237969a At the end of the day, I don't think I want to maintain grf3, feature-space and ix inside guile-wiredtiger because they are much more than wiredtiger bindings. So I am pondering the fact that I will drop those databases abstraction from guile wiredtiger and focus on improving the core bindings (like actionable exceptions) and maybe improve bindings coverage. For the next release 0.8 of guile-wiredtiger, the abstractions grf3, feature-space and ix will be deprecated. And after for 0.9 release they will be moved to the example folder (or better, forked by other people to be maintained separatly). > Ultimately I want to be able to deploy with something like: > > $ guix system disk-image gnupaste-system.scm > > Then boot it up in a VPS. That will be neat! > > Thanks! > Kris -- Amirouche ~ amz3 ~ http://www.hyperdev.fr