[Backgroundrb-devel] A fix for bdrb crash when running in background

Wojciech Knapik webmaster at wolniartysci.pl
Wed Jun 18 09:04:05 EDT 2008


Hi everyone

  I just spent way too much time trying to figure out why the fsck bdrb 
wouldn't run in background (while it worked perfecly in foreground), so 
I figured I'll share my unimpressive solution to save others the trouble.
  So the problem was that bdrb, when started with `script/backgroundrb 
start`, would exit, with this error msg:

/usr/lib64/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/abstract_adapter.rb:150:in 
`log': PGError: server closed the connection unexpectedly 
(ActiveRecord::StatementInvalid)
         This probably means the server terminated abnormally
         before or while processing the request.
:           SELECT tablename
             FROM pg_tables
            WHERE schemaname IN (E'"$user"',E'public')
         from 
/usr/lib64/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/postgresql_adapter.rb:395:in 
`query'
         from 
/usr/lib64/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/postgresql_adapter.rb:441:in 
`tables'

  Starting it with `script/backgroundrb` didn't cause that problem, 
everything worked fine.
  This happened exactly the same way on a G5/OSX/Postgres 8.2.4/Rails 
2.0.2 workstation and a Xeon/Gentoo/Postgres 8.3.1/Rails 2.0.2 server. 
Considering the different setups and the complete lack of complaints 
from Postgres, even with highest logging verbosity AND the smoothly 
working rails app, I figured it must be a problem with backgroundrb, but 
whatever changes I tried, nothing worked. So fast forward (to spare you 
the story of the cursing and the hopeless googling) - here's the 
solution - line 32 of script/backgroubdrb:

  29 case ARGV[0]
  30 when 'start'
  31   if fork
  32     sleep(5)
  33     exit
  34   else

  Apparently leaving the child on it's own too early is not a good thing :-o
  So there. Here's my good deed for the day.

cheers,
Wojtek

PS. Thanks guys for bdrb!



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