I can't believe I never knew about Cabal. I'm getting Orc now. It looks very interesting. Thanks for the help. -Eitan On 7/28/2010 9:17 PM, Günther Schmidt wrote:
Hi Eitan,
I'm right now approaching the subject of concurrency myself for the first time in an application that spiders web pages. The getting the web pages part via http request is the one that is time consuming and thus the one that I wish to "concurrentalize", ie. getting up to 6 six pages concurrently at a time.
From what I've learned so far it seems that there are the following approaches to concurrency in haskell:
1. use a primitive approach with the concurrency primitives that haskell / ghc provides, ie. locks, MVars, TVars etc. directly
2. use one abstraction level up, ie. use STM (Software Transactional Memory), there is a chapter in RWH about it.(also available online).
3. use yet another abstraction level up by using the orc library from the galois people, available on hackage. Documentation to this one is a paper available on the galois website. I am currently at the very beginning of familiarizing myself with this approach but it seems the most feasible way to do concurrency. Using this approach is pretty much like not having to worry about garbage collection. Even using STM you still have to do a lot of your own manual forkIO, putVar, kill etc.
Best regards
Günther
Am 29.07.10 02:23, schrieb Eitan Goldshtrom:
Hi everyone. I was wondering if someone could just guide me toward some good information, but if anyone wants to help with a personal explanation I welcome it. I'm trying to write a threaded program and I'm not sure how to manage my memory. I read up on MVars and they make a lot of sense. My real question is what is "atomic" and how does it apply to TVars? I don't understand what atomic transactions are and I can't seem to find a concise explanation. I also saw some stuff about TMVars? But I can't find much on them either. Any help would be appreciated.
-Eitan
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