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Idioms: Building High Performance Networking Servers Using Tcl (2006)

38 points by ghosthamlet 12y ago

NicoJuicy 12y ago
I think the article is from 2004 instead of 2006. None the less, i'm wondering if this statement still stands: Tcl is slower than C, but the network is slower than Tcl.
- sebcat 12y ago
  It's apt to compare Tcl to Node.JS because of the similar I/O-model. Tcl is slower than Node.JS (a broad statement, but e.g., it's not JITed), and the last time I checked Tcl's event loop was select-based and not epoll/kqueue-based. Looking at the code for 8.6.2, it appears to be like that still. I like Tcl, but I wouldn't use it for high-concurrency tasks (I would use Go for that). It's nice when you need a DSL to extend your application, or if you want to glue C libraries together, but there are better tools for network code.
  - justincormack 12y ago
    The similar IO model? It is just the Unix IO model though, with the caveat to never use blocking IO. Tcl doesn't force non blocking IO like Node, you have to do it yourself. Event based IO was around by 1999 or earlier, according to the C10k page that we all avidly read backin the day http://www.kegel.com/c10k.html http://www.kegel.com/c10k.html
    - sebcat 12y ago
      Both Tcl and Node.JS are built around the concept of an event loop. The preffered way to do IO in both languages is to express your network application as a FSM with callbacks on state transitions. Of course event driven IO is not in any way "owned" by either languages, what I mean is that they both encourage an event-driven IO model. Am I making myself clear?
- ZoFreX 12y ago
  F5 load balancers still use Tcl, albeit a modified and optimised version. If anyone is reading this article and thinking "Gee, I wish I could get a job writing Tcl", hit me up.
  - marktangotango 12y ago
    iRules are a horror that should've been killed at birth.
  - ciupicri 12y ago
    For me it's more like gee, I had a job writing Tcl and it was so much "fun". I've just tried the example from "Read messages chunk by available chunk" and got: invalid command name "handle_data sock4" while executing "[list handle_data $chan] " (procedure "handle_client" line 8) invoked from within "handle_client sock4 127.0.0.1 40642" I replaced [list handle_data $chan] with a plain handle_data $chan, but then another bug come up: invalid command name "buf" while executing "buf sock4,data_ready write" (write trace on "buf(sock4,data_ready)") invoked from within "set buf($chan,data_ready) 0" (procedure "handle_data" line 4) The fun never stops :-) In a way Tcl makes shell scripting (Bash) look wonderful because at least there you can't expect much from it, whereas Tcl presents itself more like a "real", full-blown programming language.
    - adunsmoor 12y ago
      Your error looks like there might be an extra space after the line continuation (backslash) in the example. The trace command is split in to 2 lines for readability but the web page's formatting introduced a hidden space if you try to copy/paste the example in to a tcl script.
      - ciupicri 12y ago
        Yes, you're right.
  - kjs3 12y ago
    The Cisco IOS operating system includes TCL scripting as well.
davidw 12y ago
Tcl - doing event loops before event loops were cool.
idiom 12y ago
I know this articles was published 7-8 years ago at http://idioms.in http://idioms.in
smrtinsert 12y ago
I just picked up PureData and have been enjoying learning about it and sound generation - also written in tcl/tk!
regi 12y ago
"From SMTP filters/routers that handle millions of email deliveries a week to in-memory message journaling (for redundancy) that handle hundreds of transactions per second." I stopped right there. To me, high performance is for instance, handling millions of emails per minute, thousands or tenth of thousand TPS. This is high performance, real life performance, not seen only in "physic labs and university research centers". Some comments talk about Tcl using select. If this is true, it would mean a max of 1024 connections in parallel, kind of sad...
- rakoo 12y ago
  This article was written in 2006. What was considered high performance at the time ? (genuine question)
  - regi 12y ago
    The C10k problem is 15-20 years old. Tcl uses select() which can handle a maximum of 1024 FDs. In other words, it would not be able to handle more than 1024 connections in parallel. Moreover, Linux and FreeBSD have introduced syscalls comparable to select(): epoll (in 2002) and kqueue (in 2000). Those are way faster than select() and I think there's (virtually) no limit on FDs. Tcl must be using select() for its portability I guess. So, handling a lot of concurrent connections is an old problem. In 2006, the C10k problem was way behind. Even at that time, I would have expected a program to be able to handle thousands of TPS.
- incision 12y ago
  >'I stopped right there.' This is obnoxious, way too common and as another comment points out seemingly aloof to the fact that the article is 8 years old. Please, just to stick to self-promotion [1][2][3][4]. 1: https://news.ycombinator.com/item?id=6560909 https://news.ycombinator.com/item?id=6560909 2: https://news.ycombinator.com/item?id=6573974 https://news.ycombinator.com/item?id=6573974 3: https://news.ycombinator.com/item?id=8086250 https://news.ycombinator.com/item?id=8086250 4: https://news.ycombinator.com/item?id=8200975 https://news.ycombinator.com/item?id=8200975
  - 12y ago

38 points by ghosthamlet 12y ago

I think the article is from 2004 instead of 2006. None the less, i'm wondering if this statement still stands: Tcl is slower than C, but the network is slower than Tcl.

sebcat 12y ago
It's apt to compare Tcl to Node.JS because of the similar I/O-model. Tcl is slower than Node.JS (a broad statement, but e.g., it's not JITed), and the last time I checked Tcl's event loop was select-based and not epoll/kqueue-based. Looking at the code for 8.6.2, it appears to be like that still. I like Tcl, but I wouldn't use it for high-concurrency tasks (I would use Go for that). It's nice when you need a DSL to extend your application, or if you want to glue C libraries together, but there are better tools for network code.
- justincormack 12y ago
  The similar IO model? It is just the Unix IO model though, with the caveat to never use blocking IO. Tcl doesn't force non blocking IO like Node, you have to do it yourself. Event based IO was around by 1999 or earlier, according to the C10k page that we all avidly read backin the day http://www.kegel.com/c10k.html http://www.kegel.com/c10k.html
  - sebcat 12y ago
    Both Tcl and Node.JS are built around the concept of an event loop. The preffered way to do IO in both languages is to express your network application as a FSM with callbacks on state transitions. Of course event driven IO is not in any way "owned" by either languages, what I mean is that they both encourage an event-driven IO model. Am I making myself clear?
ZoFreX 12y ago
F5 load balancers still use Tcl, albeit a modified and optimised version. If anyone is reading this article and thinking "Gee, I wish I could get a job writing Tcl", hit me up.
- marktangotango 12y ago
  iRules are a horror that should've been killed at birth.
- ciupicri 12y ago
  For me it's more like gee, I had a job writing Tcl and it was so much "fun". I've just tried the example from "Read messages chunk by available chunk" and got: invalid command name "handle_data sock4" while executing "[list handle_data $chan] " (procedure "handle_client" line 8) invoked from within "handle_client sock4 127.0.0.1 40642" I replaced [list handle_data $chan] with a plain handle_data $chan, but then another bug come up: invalid command name "buf" while executing "buf sock4,data_ready write" (write trace on "buf(sock4,data_ready)") invoked from within "set buf($chan,data_ready) 0" (procedure "handle_data" line 4) The fun never stops :-) In a way Tcl makes shell scripting (Bash) look wonderful because at least there you can't expect much from it, whereas Tcl presents itself more like a "real", full-blown programming language.
  - adunsmoor 12y ago
    Your error looks like there might be an extra space after the line continuation (backslash) in the example. The trace command is split in to 2 lines for readability but the web page's formatting introduced a hidden space if you try to copy/paste the example in to a tcl script.
    - ciupicri 12y ago
      Yes, you're right.
- kjs3 12y ago
  The Cisco IOS operating system includes TCL scripting as well.

davidw 12y ago

Tcl - doing event loops before event loops were cool.

idiom 12y ago

I know this articles was published 7-8 years ago at http://idioms.in http://idioms.in

smrtinsert 12y ago

I just picked up PureData and have been enjoying learning about it and sound generation - also written in tcl/tk!

regi 12y ago

"From SMTP filters/routers that handle millions of email deliveries a week to in-memory message journaling (for redundancy) that handle hundreds of transactions per second." I stopped right there. To me, high performance is for instance, handling millions of emails per minute, thousands or tenth of thousand TPS. This is high performance, real life performance, not seen only in "physic labs and university research centers". Some comments talk about Tcl using select. If this is true, it would mean a max of 1024 connections in parallel, kind of sad...

rakoo 12y ago
This article was written in 2006. What was considered high performance at the time ? (genuine question)
- regi 12y ago
  The C10k problem is 15-20 years old. Tcl uses select() which can handle a maximum of 1024 FDs. In other words, it would not be able to handle more than 1024 connections in parallel. Moreover, Linux and FreeBSD have introduced syscalls comparable to select(): epoll (in 2002) and kqueue (in 2000). Those are way faster than select() and I think there's (virtually) no limit on FDs. Tcl must be using select() for its portability I guess. So, handling a lot of concurrent connections is an old problem. In 2006, the C10k problem was way behind. Even at that time, I would have expected a program to be able to handle thousands of TPS.
incision 12y ago
>'I stopped right there.' This is obnoxious, way too common and as another comment points out seemingly aloof to the fact that the article is 8 years old. Please, just to stick to self-promotion [1][2][3][4]. 1: https://news.ycombinator.com/item?id=6560909 https://news.ycombinator.com/item?id=6560909 2: https://news.ycombinator.com/item?id=6573974 https://news.ycombinator.com/item?id=6573974 3: https://news.ycombinator.com/item?id=8086250 https://news.ycombinator.com/item?id=8086250 4: https://news.ycombinator.com/item?id=8200975 https://news.ycombinator.com/item?id=8200975
- 12y ago