From: Lars Christensen <larsch@...>
Date: 2008-04-23T21:50:13+09:00
Subject: Re: Deadlock in DRb

On Apr 22, 3:45 pm, Robert Klemme <shortcut...@googlemail.com> wrote:
> 2008/4/22, Lars Christensen <lar...@belunktum.dk>:
>
> > In a program with two DRb servers running (two time start_service), i
>
> Why do you have two servers?

Well... legacy. I have converted my application to having only 1 DRb
service started, but the same problem occurs. I still get a deadlock
after the clients have been connecting for a while.

> For adeadlockyou need at least two resources that are locked in
> different order.  Maybe you have synchronized calls across the two
> servers thatdeadlock.

My main thread is blocked by DRb.thread.join. All other threads are
inside the DRb library on either Socket#accept, #read or #write.

How can there be a deadlock if a thread is waiting in a Socket#accept
call? As I understand the Ruby deadlock detection is simply fires when
there is no thread to run.

> You could use set_trace_func to trace program execution until thedeadlockand look at the execution flow.

I have tried this, but it doesn't show anything other that the
deadlock report from Ruby, i.e. that the threads are calling
Socket#accept, #read or #write and Thread#join.

Lars