在 puma worker 上发生 Sequel::DatabaseDisconnectError，即使数据库在 puma 的 before_fork-hook

编程问答 2022-05-23

问题描述

我有一个 hanami 1.3 应用程序，但问题应该与 hanami 无关。我想用普通的 Sequel-gem 连接到第二个数据库。因此，我在 hanami 的 config/environment.rb 中定义了连接：

# config/environment.rb
# ...
DWH = Sequel.connect(ENV['DWH'],:loggers => [Logger.new($stdout)])
#...

在生产中，我有一个像这样的 puma-config：

# config/puma.rb
require_relative './environment'
workers 5

threads_count = 1
threads threads_count,threads_count

daemonize true

preload_app!

rackup      DefaultRackup
port        2300
environment 'production'

before_fork do
  DWH.disconnect
end

on_worker_boot do
  Hanami.boot
end

我使用 before_fork 钩子断开数据库 (http://sequel.jeremyevans.net/rdoc/files/doc/fork_safety_rdoc.html)。但一段时间后，我收到了这样的错误：

Sequel::DatabaseDisconnectError: PG::UnableToSend: SSL SYSCALL error: EOF detected
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:166:in `async_exec'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:166:in `block in execute_query'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/database/logging.rb:49:in `log_connection_yield'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:166:in `execute_query'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:153:in `block in execute'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:129:in `check_disconnect_errors'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:153:in `execute'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:515:in `_execute'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:327:in `block (2 levels) in execute'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:537:in `check_database_errors'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:327:in `block in execute'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/database/connecting.rb:301:in `block in synchronize'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/connection_pool/threaded.rb:107:in `hold'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/database/connecting.rb:301:in `synchronize'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:327:in `execute'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/dataset/actions.rb:1135:in `execute'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/adapters/postgres.rb:680:in `fetch_rows'
    /home/usr/vendor/bundle/ruby/2.6.0/gems/sequel-4.49.0/lib/sequel/dataset/actions.rb:155:in `each'
  /home/usr/app/lib/repositories/dwh_repository.rb:39:in `to_a'

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