From 7b21b23bb41848ff59e59045f7f1fb975b3b9e66 Mon Sep 17 00:00:00 2001
From: Jeremy Evans <code@jeremyevans.net>
Date: Tue, 27 Aug 2019 11:36:44 -0700
Subject: [PATCH] Detect fork and do not reuse forked connections in drb

This associates each DRbConn with a pid, and if the pid changes,
it closes any DRbConns in the pool with a pid that no longer
matches.  This fixes DRb servers from sending messages intended
for one client to another client after forking.

Fixes [Bug #2718]
Fixes [Bug #14471]
---
 lib/drb/drb.rb | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/lib/drb/drb.rb b/lib/drb/drb.rb
index caffd5df25..bff83a09c4 100644
--- a/lib/drb/drb.rb
+++ b/lib/drb/drb.rb
@@ -1209,15 +1209,20 @@ class DRbConn
     def self.open(remote_uri)  # :nodoc:
       begin
         conn = nil
+        pid = $$
 
         @mutex.synchronize do
           #FIXME
           new_pool = []
           @pool.each do |c|
-            if conn.nil? and c.uri == remote_uri
-              conn = c if c.alive?
+            if c.pid == pid
+              if conn.nil? and c.uri == remote_uri
+                conn = c if c.alive?
+              else
+                new_pool.push c
+              end
             else
-              new_pool.push c
+              c.close
             end
           end
           @pool = new_pool
@@ -1243,9 +1248,11 @@ def self.open(remote_uri)  # :nodoc:
 
     def initialize(remote_uri)  # :nodoc:
       @uri = remote_uri
+      @pid = $$
       @protocol = DRbProtocol.open(remote_uri, DRb.config)
     end
     attr_reader :uri  # :nodoc:
+    attr_reader :pid  # :nodoc:
 
     def send_message(ref, msg_id, arg, block)  # :nodoc:
       @protocol.send_request(ref, msg_id, arg, block)
-- 
2.22.0