[ruby-core:31305] [Bug #3577] Segmentation fault doing simple MySQL queries

Bug #3577: Segmentation fault doing simple MySQL queries
http://redmine.ruby-lang.org/issues/show/3577

Author: Jon Rosen
Status: Open, Priority: Normal
ruby -v: 1.9.1

I am a relative ruby-newbie (hey that rhymes!) but I am a python expert
so this error REALLY threw me.  I am doing a VERY VERY simply SQL
program that executes two queries in a row:

  require 'mysql'
  db = Mysql.connect('localhost','myname','mypswd','information_schema')
  q1 = db.query ("select * from table_constraints")
  q1.each { |row| puts row.inspect }
  q1.free
  q2 = db.query ("select * from key_column_usage")
  q2.each { |row| puts row.inspect }
  q2.free
  db.close

This SHOULD just print the data from the two schema tables.

When I execute this with EITHER of the sets of three lines for q1 or q2
commented out (i.e., only one query in the program), this works fine.
Each run gives me the correct results from the appropriate query.

When I execute this as above, I get the following:

  C:\ruby>ruby sqlcompare1.rb
  [nil, "qautil", "PRIMARY", "qautil", "qausers", "PRIMARY KEY"]
  [nil, "qautil", "PRIMARY", "qautil", "siteuimap", "PRIMARY KEY"]
  [nil, "qautil", "map_page_field", "qautil", "siteuimap", "UNIQUE"]
  [nil, "qautil", "PRIMARY", "qautil", "testusers", "PRIMARY KEY"]
  sqlcompare1.rb:6: [BUG] Segmentation fault
  ruby 1.9.1p429 (2010-07-02 revision 28523) [i386-mingw32]

  -- control frame ----------
  c:0008 p:---- s:0023 b:0023 l:000022 d:000022 CFUNC  :inspect
  c:0007 p:---- s:0021 b:0021 l:000020 d:000020 CFUNC  :inspect
  c:0006 p:0012 s:0018 b:0017 l:001264 d:000016 BLOCK  sqlcompare1.rb:6
  c:0005 p:---- s:0014 b:0014 l:000013 d:000013 FINISH
  c:0004 p:---- s:0012 b:0012 l:000011 d:000011 CFUNC  :each
  c:0003 p:0065 s:0009 b:0009 l:001264 d:000b58 EVAL   sqlcompare1.rb:6
  c:0002 p:---- s:0004 b:0004 l:000003 d:000003 FINISH
  c:0001 p:0000 s:0002 b:0002 l:001264 d:001264 TOP
  ----------Ruby level backtrace information----------
  sqlcompare1.rb:6:in `inspect'
  sqlcompare1.rb:6:in `inspect'
  sqlcompare1.rb:6:in `block in <main>'
  sqlcompare1.rb:6:in `each'
  sqlcompare1.rb:6:in `<main>'

  [NOTE]
  You may encounter a bug of Ruby interpreter. Bug reports are welcome.
  For details: http://www.ruby-lang.org/bugreport.html

  This application has requested the Runtime to terminate it in an unusual way.
  Please contact the application's support team for more information.

  C:\ruby>

Needless to say, this looks REALLY nasty and doesn't instill a lot of
confidence in me about the stability of the MySQL/Ruby code.  I am
running Ruby 1.9.1 and MySQL 2.8.1 which are the latest and greatest as
far as I know.

Just for the record, the following python version of the same code:

  import MySQLdb
  db = MySQLdb.connect('localhost','myname','mypswd','information_schema')
  q = db.cursor()
  q.execute("select * from table_constraints")
  for row in q.fetchall():
    print row
  q.execute("select * from key_column_usage")
  for row in q.fetchall():
    print row

WORKS PERFECTLY! :-)

I can't even imagine that with something this simple blowing up that
there are thousands of Ruby/MySQL applications out there running on
websites flawlessly.  There must be REALLY something weird going on
here.

Thanks,

Jon "bleurose" Rosen


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