pro August 2016

pro@common-lisp.net

7 participants
2 discussions

Detecting at runtime when bindings go out of scope?
by David McClain 26 Aug '16

26 Aug '16

I have been reworking my Reppy Channels for the past week or so. Then I ran into this article from yore… http://erikdemaine.org/papers/CCC97/paper.ps <http://erikdemaine.org/papers/CCC97/paper.ps> The article prompted me to wonder about Lisp bindings. We all know how to write a macro to protect and discard resources, e.g., (defmacro with-channel (ch &body body) `(let ((,ch (make-channel))) (unwind-protect (progn ,@body) (discard-channel ch)))) And that works just fine. At the end of use for the ephemeral channel, we discard it, and hence scavenge up any threads that might have been waiting on it. Threads are a relatively precious system resource, and so scavenging is a useful thing to do. They won’t ever be garbage collected because, typically, the Lisp system keeps a list of running threads. Hence there will always be outstanding, if useless, references to them. But then I began wondering if there could be a way to automatically detect when a resource goes out of scope / context? Why should we have to write the WITH- macros? Memory is automatically reclaimed. Why couldn’t we have a method that could also automatically reclaims vital system resources? Of course if the channel were ever handed off to another thread and stored away somewhere, it shouldn’t be reclaimed. But I already have GC finalization to help with that case. What I’m wondering about is being able to declare an item, a special kind of Constructor parameter, which refers to a system resource that needs scavenging, such that I could forego the WITH- formalism? Maybe I’m asking for too much here… how would we ever detect the item being stored? We’d need reference counting, and I tend to dislike that approach very much.. Anyone ever seen a system for resource reclamation that is better than WITH- and UNWIND-PROTECT? - DM

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[funding][mcclim]
by Daniel Kochmański 12 Aug '16

12 Aug '16

Hey, as some of you probably know McCLIM project slowly progresses forward thanks to Robert Strandh support and help from various contributors. Today we've started a fundraiser on the Bountsource (salt) platform and we hope to secure the development thanks to that. You may read a blog post written by Robert at https://common-lisp.net/project/mcclim/posts/Crowdfunding-McCLIM-maintenanc… (McCLIM's blog). Thanks, Daniel Kochmański -- Daniel Kochmański ;; aka jackdaniel | Poznań, Poland TurtleWare - Daniel Kochmański | www.turtleware.eu "Be the change that you wish to see in the world." - Mahatma Gandhi

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pro August 2016