zellux 的博客

Live Code Update in Erlang Joe Armstrong的原话 Live code upgrading is one of the things Erlang was designed for. 一个最简单的例子 loop(Fun, State) receive {From, {rpc, Tag, Q}} -> {Reply, State1} = Fun(Q, State), From ! {Tag, Reply}, loop(Fun, State1); {code_upgrade, Fun1} -> loop(Fun1, State) end. 使用时只要发送一个{code_update, Fun1}消息即可 在实际的项目中,live code update需要在一个进程的稳定状态中进行。好在有Erlang天生的分布式特性,结点i进行更新时其他结点可以接管这个结点的任务,直到结点i更新成功,再进行下一个结点的更新。这个形式和结点的crash处理有点类似。于是Erlang中live updating的实际难点在于 1. How to suspend the system and put it into a stable state 2. How to replicate the stable state 3. How to restart from a stable state 4. 阅读全文 →