ruby-on-rails - 当池大小小于线程数时避免 ConnectionTimeoutError

Question

我能否确保连接池大小小于并发使用 ActiveRecord 连接的线程数？我希望线程池大小为一个。

我遇到错误:

could not obtain a database connection within 5.000       
conds (waited 5.000 seconds) ActiveRecord::ConnectionTimeoutError)

我正在尝试在我的本地机器上模拟它。但在这里我也面临着同样的错误。

@db_host  = "localhost"
@db_user  = "root"
@db_pass  = "root"
@db_name = "me_dev1"

ActiveRecord::Base.establish_connection(  
:adapter => "mysql2",  
:host => @db_host,  
:database => @db_name,  
:pool     => 1,
:reaping_frequency => 1
)  

class Test < ActiveRecord::Base  
   def create_data

      100.times do |i|
        t1=Thread.new {
         begin
          test=Test.where(:test_name => "automation test")
          puts test
         ensure
          ActiveRecord::Base.connection.close if ActiveRecord::Base.connection ;
          ActiveRecord::Base.clear_active_connections! ;
        end
     }
    t1.join
   end
   end 
end 

Test.new.create_data

谢谢

Answer 1

ActiveRecord 为每个线程使用一个单独的连接。使此代码工作的可靠方法是使池大小大于或等于线程数。

如果您希望池大小小于线程数，您应该增加 ActiveRecord 等待从池中获取连接的时间量。这是通过 checkout_timeout 选项完成的，例如:

ActiveRecord::Base.establish_connection(  
  ...
  checkout_timeout: 3_600,    # wait an hour
)