Bug #5618: Exceptions cause DRb connection to be closed

• Status: Closed
• Assignee: seki (Masatoshi Seki)
• Target version: -
• ruby -v: ruby 1.9.3p0 (2011-10-30) [i386-mingw32]

[larsch (Lars Christensen)]

If an exception is thrown in a DRb server of a class that is not defined in the client process, the DRb connection is closed abrubtly. In Ruby 1.8, the exception was translated to an instance generic exception class (DRb::DRbRemoteError).

Steps to reproduce:

1. Start DRb client+server
2. Throw exception of custom class in server (class not defined in client script).

Observed behaviour:

3. Client raises DRb::DRbConnError because connection is closed - used to be generic error.

Expected behaviour:

3. Client raises DRb::DRbRemoteError, and preserves full stack trace from server.

Attached is server/client script showing the problem.

Here is the stack trace of the client:

C:/lang/Ruby193/lib/ruby/1.9.1/drb/drb.rb:570:in load': connection closed (DRb::DRbConnError) from C:/lang/Ruby193/lib/ruby/1.9.1/drb/drb.rb:632:in recv_reply'
from C:/lang/Ruby193/lib/ruby/1.9.1/drb/drb.rb:918:in recv_reply' from C:/lang/Ruby193/lib/ruby/1.9.1/drb/drb.rb:1197:in send_message'
from C:/lang/Ruby193/lib/ruby/1.9.1/drb/drb.rb:1088:in block (2 levels) in method_missing' from C:/lang/Ruby193/lib/ruby/1.9.1/drb/drb.rb:1172:in open'
from C:/lang/Ruby193/lib/ruby/1.9.1/drb/drb.rb:1087:in block in method_missing' from C:/lang/Ruby193/lib/ruby/1.9.1/drb/drb.rb:1105:in with_friend'
from C:/lang/Ruby193/lib/ruby/1.9.1/drb/drb.rb:1086:in method_missing' from drbclient.rb:3:in '

[ko1 (Koichi Sasada)]

• Category set to lib
• Assignee set to seki (Masatoshi Seki)

[shyouhei (Shyouhei Urabe)]

• Status changed from Open to Assigned

[felixbuenemann (Felix Bünemann)]

This issue still exists in Ruby 2.1.5.

[jeremyevans0 (Jeremy Evans)]

• File drb-rescue-exception-5618.patch drb-rescue-exception-5618.patch added

This issue is unrelated to whether the client defines the same exception class as the server, and the behavior in my testing appears to be the same on 1.8 as in the master branch.

The underlying issue is that the example code here uses a subclass of Exception, and DRb::DRbServer::InvokeMethod#perform does not rescue Exception. Attached is a patch that fixes this issue.

• Status changed from Assigned to Closed

Applied in changeset git|50b8033d6b7404670ee985de1473fffc10dd7d9c.

---

Handle subclasses of Exception in drb

This makes it so that client instances that call a method on a
server-side object that raise a subclass of Exception are handled
similarly to those that raise a subclass of StandardError.

Only reraise exceptions that we are fairly sure we don't want to
rescue.

Fixes [Bug #5618]