Created
August 15, 2011 09:55
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require 'pg' | |
# 接続先 DB の情報 | |
DB_S_ARRAY = [ 'localhost', 5432, '', '', 'db_name', 'user_name', 'password' ] | |
# テーブル table_name に対して先にロックを獲得するスレッド | |
t1 = Thread.new do | |
dbconn = PGconn.connect( *DB_S_ARRAY ) | |
dbconn.transaction do | |
puts 'locking table... (t1)' | |
dbconn.exec( 'LOCK TABLE table_name IN EXCLUSIVE MODE' ){} | |
puts 'locked table!! (t1)' | |
# ロック獲得後, スレッド t2 がロックを獲得しようとするまで待つ | |
sleep 3 | |
end | |
puts 'unlocked table!! (t1)' | |
end | |
sleep 1 | |
# テーブル table_name に対して後からロックを獲得しようとするスレッド | |
t2 = Thread.new do | |
dbconn = PGconn.connect( *DB_S_ARRAY ) | |
dbconn.transaction do | |
puts 'locking table... (t2)' | |
# この関数の中でずっと待ち状態になってしまってデッドロック | |
dbconn.exec( 'LOCK TABLE table_name IN EXCLUSIVE MODE' ){} | |
puts 'locked table!! (t2)' | |
end | |
puts 'unlocked table!! (t2)' | |
end | |
t1.join() | |
t2.join() | |
# --- output (ruby 1.9.2) --- | |
# locking table... (t1) | |
# locked table!! (t1) | |
# locking table... (t2) | |
# (これ以降処理が進まない) |
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