Thanks! All implementations works now. A typo fix in Go implementation was not enough. You can't write message by parts, have to form it in buffer before writing.
ratrace helped to find problem with Ruby/Python implementations. https://gist.github.com/912377#file_ratrace.log shows that both writes to data after reading ctl. Fixed with a flush call. > Also, you should really check the errors from any system call > instead of discarding them. It may be good in production, but in development I want program crash as loud and quick as possible.
