RuntimeError - grpc cannot be used before and after forking

[taman9333]

I am using Falcon in my Sinatra app & I am using mongodb & etcd.

However I have an issue, in preload.rb file I have initialized a singleton counter

require_relative '../services/counter_service'

CounterService.initialize_counter_range

and here is the counter_service.rb file

require 'securerandom'
require 'thread'
require 'etcdv3'
require_relative '../initializers/etcd'
class CounterService
RANGE_SIZE = 1000

  class << self
    def initialize_counter_range
      self.counter_range = get_counter_range
      self.counter = counter_range.first
    end

    def get_next_counter
      current_counter = counter
      if current_counter >= counter_range.last
      puts "Worker process #{Process.pid} Exhausted counter"
      self.counter_range = get_counter_range
      self.counter = counter_range.first
      current_counter = counter
      end
      self.counter += 1
      current_counter
    end

    private

    attr_accessor :counter_range, :counter
    attr_reader :counter_mutex

    def get_counter_range
      loop do
        current_value = EtcdClient.client.get(COUNTER_KEY).kvs.first&.value.to_i
        new_value = current_value + RANGE_SIZE

        txn = EtcdClient.client.transaction do |txn|
          txn.compare = [
            txn.value(COUNTER_KEY, :equal, current_value.to_s),
          ]
          txn.success = [
            txn.put(COUNTER_KEY, new_value.to_s)
          ]
        end

        if txn.succeeded
          puts "Instance #{ENV['SERVICE_NAME']} obtained counter range #{current_value} to #{new_value - 1}"
          return (current_value...new_value)
        end
      end
    end

    def counter_mutex
      @counter_mutex ||= Mutex.new
    end
  end
end

I got this error after first counter range being exhausted & trying to get next counter

Worker process 32 Exhausted counter
RuntimeError - grpc cannot be used before and after forking:
/usr/local/bundle/gems/grpc-1.40.0/src/ruby/lib/grpc/generic/client_stub.rb:49:in `initialize'
/usr/local/bundle/gems/grpc-1.40.0/src/ruby/lib/grpc/generic/client_stub.rb:49:in `new'
/usr/local/bundle/gems/grpc-1.40.0/src/ruby/lib/grpc/generic/client_stub.rb:49:in `setup_channel'
/usr/local/bundle/gems/grpc-1.40.0/src/ruby/lib/grpc/generic/client_stub.rb:104:in `initialize'
/usr/local/bundle/gems/grpc-1.40.0/src/ruby/lib/grpc/generic/service.rb:158:in `initialize'
/usr/local/bundle/gems/etcdv3-0.11.6/lib/etcdv3/auth.rb:13:in `new'
/usr/local/bundle/gems/etcdv3-0.11.6/lib/etcdv3/auth.rb:13:in `initialize'
counter_service.rb:46:in `block in get_counter_range'
counter_service.rb:45:in `loop'
counter_service.rb:45:in `get_counter_range'
counter_service.rb:30:in `block in get_next_counter'
counter_service.rb:21:in `synchronize'
counter_service.rb:21:in `get_next_counter'

[ioquatix]

You may check: grpc/grpc#33430

Maybe try: GRPC_ENABLE_FORK_SUPPORT=1 falcon serve ...

It's also possible you are pre-loading the gem which is causing this problem. Are you using preload.rb or a bundle gem group called preload?