Feature #12101

Add verbose failure messages and avoid infamous DRb::DRbConnError

Added by yagudaev (Michael Yagudaev) almost 5 years ago. Updated almost 5 years ago.

Target version:


Avoid the generic "DRb::DRbConnError" which gives very little information and make errors hard to debug.

When I stared using DRuby, I kept getting a strange and cryptic error message DRb::DRbConnError 'connection closed'. Turns out it was due to some silly mistake on the server side of the relationship. It took hours to figure out. The only way I was able to do it was to patch ruby drb after closely studying the source.

Others have had the same issues:

Here is an example where this makes a difference:

# drb_server.rb
require 'drb'

class FrontObject
  def foo
    # generates Runtime Exception of Insecure Operation
    result = `ls -l`

DRb.start_service("druby://localhost:8787",, safe_level: 3)
# drb_client.rb
require 'drb'

object = DRbObject.new_with_uri("druby://localhost:8787")

Output before patch is applied:

$ ruby drb_server.rb
$ ruby drb_client.rb
/Users/mike/.rbenv/versions/2.2.3/lib/ruby/2.2.0/drb/drb.rb:578:in `load': connection closed (DRb::DRbConnError)

Output after patch is applied:

$ ruby drb_server.rb
Insecure operation ``' at level 3
$ ruby drb_client.rb
/Users/mike/.rbenv/versions/2.2.3/lib/ruby/2.2.0/drb/drb.rb:578:in `load': connection closed (DRb::DRbConnError)

Original issue and proposed solution started on github:

Updated by yagudaev (Michael Yagudaev) almost 5 years ago

  • Tracker changed from Bug to Feature

Updated by drbrain (Eric Hodel) almost 5 years ago

I think printing out messages to $stdout is not the best way. If I'm running DRb as a server I may have no way of seeing these and knowing if it is a problem.

Better, I think, would be to allow a user to configure a callback or logger that is invoked when an error on the client side is discovered.

See also which gives you tcpdump-like views of communications amongst drb peers.


Updated by seki (Masatoshi Seki) almost 5 years ago

  • Status changed from Open to Closed

Applied in changeset r53962.

  • lib/drb/drb.rb (error_print): Add verbose failure messages and avoid infamous DRb::DRbConnError. [Feature #12101]

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