Comments on: Hot code swapping for servers not written in Erlang http://www.codexon.com/posts/hot-code-swapping-for-servers-not-written-in-erlang Sun, 05 Sep 2010 05:11:40 +0000 hourly 1 By: wladimir http://www.codexon.com/posts/hot-code-swapping-for-servers-not-written-in-erlang/comment-page-1#comment-647 wladimir Thu, 01 Jul 2010 17:28:04 +0000 http://www.codexon.com/?p=928#comment-647 We were hot-reloading C for our chat server in 1998 or so. There's really nothing new in it, it has been possible since dynamic loading and unloading of shared libraries was possible. Possible, but it was not very *convenient* to use and program for, and very easy to make mistakes, I think that's where the new developments are centered in. We were hot-reloading C for our chat server in 1998 or so. There’s really nothing new in it, it has been possible since dynamic loading and unloading of shared libraries was possible. Possible, but it was not very *convenient* to use and program for, and very easy to make mistakes, I think that’s where the new developments are centered in.

]]> By: Kjartan http://www.codexon.com/posts/hot-code-swapping-for-servers-not-written-in-erlang/comment-page-1#comment-637 Kjartan Thu, 24 Jun 2010 00:20:23 +0000 http://www.codexon.com/?p=928#comment-637 Sorry for commenting on an old article, but you can hot swap code if you use the twisted framework... We do this all the time on our server, I've never had any problems with it. Sorry for commenting on an old article, but you can hot swap code if you use the twisted framework… We do this all the time on our server, I’ve never had any problems with it.

]]> By: admin http://www.codexon.com/posts/hot-code-swapping-for-servers-not-written-in-erlang/comment-page-1#comment-564 admin Wed, 24 Mar 2010 03:27:42 +0000 http://www.codexon.com/?p=928#comment-564 The most important part about code reloading is maintaining an uninterrupted service to the user. This shows that it is possible to do even in C. Obviously Erlang's immutability makes this easier, but you will probably want to upgrade the VM from time to time, and I believe there is no mechanism to do that without restarting the process. The most important part about code reloading is maintaining an uninterrupted service to the user. This shows that it is possible to do even in C.

Obviously Erlang’s immutability makes this easier, but you will probably want to upgrade the VM from time to time, and I believe there is no mechanism to do that without restarting the process.

]]> By: Tim http://www.codexon.com/posts/hot-code-swapping-for-servers-not-written-in-erlang/comment-page-1#comment-562 Tim Tue, 23 Mar 2010 15:37:35 +0000 http://www.codexon.com/?p=928#comment-562 Update : I just saw your earlier post on "A Better Python Reload". I think that answers my question, viz : it can be done, but it's not seamless, and has some drawbacks. It certainly doesn't match the way it's done in Erlang. I think it's fair to say that a clean fast code reload mechanism is always going to be clumsy in mutable languages, or at least significantly harder than in immutables languages where their very nature makes it trivial. Update : I just saw your earlier post on “A Better Python Reload”. I think that answers my question, viz : it can be done, but it’s not seamless, and has some drawbacks.

It certainly doesn’t match the way it’s done in Erlang.

I think it’s fair to say that a clean fast code reload mechanism is always going to be clumsy in mutable languages, or at least significantly harder than in immutables languages where their very nature makes it trivial.

]]> By: Tim http://www.codexon.com/posts/hot-code-swapping-for-servers-not-written-in-erlang/comment-page-1#comment-561 Tim Tue, 23 Mar 2010 15:32:01 +0000 http://www.codexon.com/?p=928#comment-561 Nice work, interesting. I'm not very familiar with Python, are there any mechanisms for preserving the state of objects across the upgrade ? I think that is a critical component for this to be of use in a broader sense. i.e. if the server is long running then presumably it has state that needs preserving ; if it doesn't have state then it's likely you could just do a quick restart without impact to the application. In the case of Erlang OTP the upgrade inherently includes preservation of state, i.e. values of variables, without use of any work-arounds in application code ; and it does it very quickly and seamlessly. Nice work, interesting. I’m not very familiar with Python, are there any mechanisms for preserving the state of objects across the upgrade ? I think that is a critical component for this to be of use in a broader sense. i.e. if the server is long running then presumably it has state that needs preserving ; if it doesn’t have state then it’s likely you could just do a quick restart without impact to the application. In the case of Erlang OTP the upgrade inherently includes preservation of state, i.e. values of variables, without use of any work-arounds in application code ; and it does it very quickly and seamlessly.

]]> By: admin http://www.codexon.com/posts/hot-code-swapping-for-servers-not-written-in-erlang/comment-page-1#comment-529 admin Mon, 25 Jan 2010 23:07:23 +0000 http://www.codexon.com/?p=928#comment-529 The point here is that it is possible to seamlessly transfer control of the sockets to a new process. Therefore to a client, it appears as though nothing has changed. The point here is that it is possible to seamlessly transfer control of the sockets to a new process. Therefore to a client, it appears as though nothing has changed.

]]> By: Yogish Baliga http://www.codexon.com/posts/hot-code-swapping-for-servers-not-written-in-erlang/comment-page-1#comment-528 Yogish Baliga Mon, 25 Jan 2010 17:38:09 +0000 http://www.codexon.com/?p=928#comment-528 I am not sure what is the point you want to make here. Spawning a new process always read the latest copy from the disk. That is not a discovery. What erlang provides is hot code loading into the currently running VM with no special code. I am not sure what is the point you want to make here. Spawning a new process always read the latest copy from the disk. That is not a discovery. What erlang provides is hot code loading into the currently running VM with no special code.

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