我使用的是redis信号量gem版本 0.3.1 .
由于某些原因，我偶尔不能释放一个过时的redis锁。根据我的分析，如果我的docker进程在锁创建后崩溃，那么这种情况似乎会发生。
我已经在下面描述了我的调试过程，想知道是否有人可以建议如何进一步调试。
假设我们要创建一个具有此名称的redis锁：

name = "test"

我们在两个不同的终端窗口中插入这个变量。首先，我们运行：

def lock_for_15_secs(name)
  job = Redis::Semaphore.new(name.to_sym, redis: NonBlockingRedis.new(), custom_blpop: true, :stale_client_timeout => 15)
  if job.lock(-1) == "0"
    puts "Locked and starting"
    sleep(15)
    puts "Now it's stale, try to release in another process"
    sleep(15)
    puts "Now trying to unlock"
    unlock = job.unlock
    puts unlock == false ? "Wuhuu, already unlocked" : "Hm, should have been unlocked by another process, but wasn't"
  end
end
lock_for_15_secs(name)

在第二次跑步中：

def release_and_lock(name)
  job     = Redis::Semaphore.new(name.to_sym, redis: NonBlockingRedis.new(), custom_blpop: true, :stale_client_timeout => 15)
  release = job.release_stale_locks!
  count   = job.available_count
  puts "Release reponse is #{release.inspect} and available count is #{count}"
  if job.lock(-1) == "0"
    puts "Wuhuu, we can lock it"
    job.unlock
  else
    puts "Hmm, we can't lock it"
  end
end
release_and_lock(name)

这通常按预期进行。在15秒钟内，第二个终端无法释放锁，但在15秒钟后运行时，它会释放。下面是 release_and_lock(name) .
15秒前：

irb(main):1:0> release_and_lock(name)
Release reponse is {"0"=>"1580292557.321834"} and available count is 0
Hmm, we can't lock it
=> nil

15秒后：

irb(main):2:0> release_and_lock(name)
Release reponse is {"0"=>"1580292557.321834"} and available count is 1
Wuhuu, we can lock it
=> 1
irb(main):3:0> release_and_lock(name)
Release reponse is {} and available count is 1
Wuhuu, we can lock it

但是每当我看到一个过时的锁没有被释放，我就跑 release_and_lock(name) 要进行诊断，将返回：

irb(main):4:0> release_and_lock(name)
Release reponse is {} and available count is 0
Hmm, we can't lock it

在这一点上，我唯一的选择就是刷新redis：

require 'non_blocking_redis'
non_blocking_redis = NonBlockingRedis.new()
non_blocking_redis.flushall

p、 s.我的 NonBlockingRedis 继承自 Redis :

class Redis
  class Semaphore
    def initialize(name, opts = {})
      @custom_opts          = opts
      @name                 = name
      @resource_count       = opts.delete(:resources) || 1
      @stale_client_timeout = opts.delete(:stale_client_timeout)
      @redis                = opts.delete(:redis) || Redis.new(opts)
      @use_local_time       = opts.delete(:use_local_time)
      @custom_blpop         = opts.delete(:custom_blpop) # false=queue, true=cancel
      @tokens               = []
    end

    def lock(timeout = 0)
      exists_or_create!
      release_stale_locks! if check_staleness?
      token_pair    = @redis.blpop(available_key, timeout, @custom_blpop)
      return false if token_pair.nil?
      current_token = token_pair[1]
      @tokens.push(current_token)
      @redis.hset(grabbed_key, current_token, current_time.to_f)
      if block_given?
        begin
          yield current_token
        ensure
          signal(current_token)
        end
      end
      current_token
    end
    alias_method :wait, :lock
  end
end

class NonBlockingRedis < Redis

  def initialize(options = {})
    if options.empty?
      options = {
        url: Rails.application.secrets.redis_url,
        db:  Rails.application.secrets.redis_sidekiq_db,
        driver: :hiredis,
        network_timeout: 5
      }
    end

    super(options)
  end

  def blpop(key, timeout, custom_blpop)
    if custom_blpop
      if timeout == -1
        result = lpop(key)
        return result if result.nil?
        return [key, result]
      else
        super(key, timeout)
      end
    else
       super
    end
  end

  def lock(timeout = 0)
    exists_or_create!
    release_stale_locks! if check_staleness?
    token_pair = @redis.blpop(available_key, timeout, @custom_blpop)
    return false if token_pair.nil?
    current_token = token_pair[1]
    @tokens.push(current_token)
    @redis.hset(grabbed_key, current_token, current_time.to_f)
    if block_given?
      begin
        yield current_token
      ensure
        signal(current_token)
      end
    end
    current_token
  end
  alias_method :wait, :lock
end

require 'non_blocking_redis'