[erlang-questions] Upgrading Erlang clusters for fun and profit

Richard Andrews <>
Mon Oct 15 08:28:08 CEST 2007

--- Joel Reymont <> wrote:

> http://wagerlabs.com/archives/125.html
> This is not for the faint-hearted!

There was no mention of where code_change() fits into the process.

I immediately thought that a two-phase commit would be useful: phase 1 to
suspend and test if the upgrade is supported; and if all nodes say ok, then
perform phase 2 to load the new code on all nodes. If any report a problem then
resume on all nodes without changing code.

But OTP doesn't seem to have any way to pre-test if the code_change callback
implementation can support the current and desired versions.

      Sick of deleting your inbox? Yahoo!7 Mail has free unlimited storage.

More information about the erlang-questions mailing list