Talk:Concurrent computing: Difference between revisions
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:I'm 99% sure Java will not output two strings at once. The [[JVM]] handles it. I don't know enough about the other languages to answer for them. --[[User:Mwn3d|Mwn3d]] 09:43, 28 February 2008 (MST) |
:I'm 99% sure Java will not output two strings at once. The [[JVM]] handles it. I don't know enough about the other languages to answer for them. --[[User:Mwn3d|Mwn3d]] 09:43, 28 February 2008 (MST) |
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::Interesting. I believe it is not an issue since ''writing'' to a stream should be ''atomically'' done, or done in a thread-safe way. The worst that can happen is messing up output, but race conditions or deadlocks or any other bad thing should not occur (at least, if messing up output is not a bad thing! EnRosejotCotayde?!) Consider that the same ''stream'' (stdout) can be ''transparently'' used by several processes (e.g. I am running Kate editor from the same shell I use to compile code, so sometimes stderr of Kate is intermixed with stdout and stderr of other tasks) --[[User:ShinTakezou|ShinTakezou]] 18:50, 17 December 2008 (UTC) |
::Interesting. I believe it is not an issue since ''writing'' to a stream should be ''atomically'' done, or done in a thread-safe way. The worst that can happen is messing up output, but race conditions or deadlocks or any other bad thing should not occur (at least, if messing up output is not a bad thing! EnRosejotCotayde?!) Consider that the same ''stream'' (stdout) can be ''transparently'' used by several processes (e.g. I am running Kate editor from the same shell I use to compile code, so sometimes stderr of Kate is intermixed with stdout and stderr of other tasks) --[[User:ShinTakezou|ShinTakezou]] 18:50, 17 December 2008 (UTC) |
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::Hm, maybe I am wrong, since for different processes the ''file'' descriptor is replicated; nonetheless they are always attached to the same terminal, and I am still thinking that race conditions are not possible. --[[User:ShinTakezou|ShinTakezou]] 19:01, 17 December 2008 (UTC) |
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Revision as of 19:01, 17 December 2008
Random order?
Is random order what is meant here, or is "any order" sufficient? --Short Circuit 00:16, 6 February 2007 (EST)
- Random order means that the order of output is not determined at compile time. The order of output may differ from one execution of the program to another due to differences in timing between the concurrent units providing the output. --Waldorf 11:47, 7 February 2007 (MST)
- "Undetermined" might be the more appropriate word. At least one of the programming examples attempts to enforce random behavior. --Short Circuit 14:17, 7 February 2007 (EST)
- Random is what I wanted. The Ada example I provided creates three separate tasks. Each one calculates a random number between 0.0 and 1.0. The task then delays the number of seconds corresponding to that random number. A delay of 0.5 lasts 0.5 seconds. There are two goals to "Simple concurrent actions". Those goals are to demonstrate the syntax for defining concurrent behavior within a single program, and the syntax for creating a random sleep or delay. --Waldorf 17:59, 7 February 2007 (MST)
- I see. You might want to explain that in the task; I thought the task's purpose was simply to demonstrate forking. --Short Circuit 20:33, 7 February 2007 (EST)
- What do you need to be clarified? I specified threads, tasks or co-routines. It can be argued that forking is a form of concurrency, which is why I specified threads, etc. Please let me know how you would like the task description to be clearer. There is currently a separate task to demonstrate forking. I have plans to explore more aspects of concurrency with tasks demonstrating synchronous and asynchonous communication between threads, etc. --Waldorf 19:27, 7 February, 2007 (MST)
- OK. I think I understand now. Your task description is probably fine. --Short Circuit 08:19, 8 February 2007 (EST)
- AFAIK Co-routines are deterministic because there is only one thread of execution at any point of time. (deterministic output). Rahul 14:48, 9 December 2008 (UTC)
- What do you need to be clarified? I specified threads, tasks or co-routines. It can be argued that forking is a form of concurrency, which is why I specified threads, etc. Please let me know how you would like the task description to be clearer. There is currently a separate task to demonstrate forking. I have plans to explore more aspects of concurrency with tasks demonstrating synchronous and asynchonous communication between threads, etc. --Waldorf 19:27, 7 February, 2007 (MST)
- I see. You might want to explain that in the task; I thought the task's purpose was simply to demonstrate forking. --Short Circuit 20:33, 7 February 2007 (EST)
- Random is what I wanted. The Ada example I provided creates three separate tasks. Each one calculates a random number between 0.0 and 1.0. The task then delays the number of seconds corresponding to that random number. A delay of 0.5 lasts 0.5 seconds. There are two goals to "Simple concurrent actions". Those goals are to demonstrate the syntax for defining concurrent behavior within a single program, and the syntax for creating a random sleep or delay. --Waldorf 17:59, 7 February 2007 (MST)
- "Undetermined" might be the more appropriate word. At least one of the programming examples attempts to enforce random behavior. --Short Circuit 14:17, 7 February 2007 (EST)
Race conditions?
It seems to me that none of the examples so far make sure that there's no attempt to output two strings at the same time. Do all the languages have reentrant output routines, or are there examples with subtle bugs in here? --Ce 09:33, 28 February 2008 (MST)
- I'm 99% sure Java will not output two strings at once. The JVM handles it. I don't know enough about the other languages to answer for them. --Mwn3d 09:43, 28 February 2008 (MST)
- Interesting. I believe it is not an issue since writing to a stream should be atomically done, or done in a thread-safe way. The worst that can happen is messing up output, but race conditions or deadlocks or any other bad thing should not occur (at least, if messing up output is not a bad thing! EnRosejotCotayde?!) Consider that the same stream (stdout) can be transparently used by several processes (e.g. I am running Kate editor from the same shell I use to compile code, so sometimes stderr of Kate is intermixed with stdout and stderr of other tasks) --ShinTakezou 18:50, 17 December 2008 (UTC)
- Hm, maybe I am wrong, since for different processes the file descriptor is replicated; nonetheless they are always attached to the same terminal, and I am still thinking that race conditions are not possible. --ShinTakezou 19:01, 17 December 2008 (UTC)