From 546e819fbe8e2585e2a226f8465d218adfb20b67 Mon Sep 17 00:00:00 2001
From: Dmitry Vorotilin <d.vorotilin@gmail.com>
Date: Mon, 28 Sep 2026 20:55:02 +0300
Subject: [PATCH] fix(client): close the socket when the browser dies before
 the close handshake

`WebSocket#close` only sends a close frame; the socket is closed by the driver's
`on_close`, which runs when the browser answers with a close frame of its own. A
browser that is already dead never answers, so `#quit` and `#restart` left the
socket open until GC finalized it -- one leaked descriptor per call, enough to
raise `Errno::EMFILE` from `Process.spawn` when browsers are restarted in a loop
under a low `nofile` limit.

Close the socket explicitly at the end of `Client#close`, after the existing
grace period for the dispatch thread, so a healthy quit still completes the
handshake through `on_close` and the forced close is a no-op there.
---
 lib/ferrum/client.rb             |  1 +
 lib/ferrum/client/web_socket.rb  | 18 ++++++++++++++++++
 sig/ferrum/client/web_socket.rbs |  2 ++
 spec/client_spec.rb              | 10 ++++++++++
 4 files changed, 31 insertions(+)

diff --git a/lib/ferrum/client.rb b/lib/ferrum/client.rb
index 4321476e..24069745 100644
--- a/lib/ferrum/client.rb
+++ b/lib/ferrum/client.rb
@@ -299,6 +299,7 @@ def close
       @pendings.clear
       @thread.kill unless @thread.join(1)
       @subscriber.close
+      @ws.force_close
     end
 
     #
diff --git a/lib/ferrum/client/web_socket.rb b/lib/ferrum/client/web_socket.rb
index cdbca237..95697e68 100644
--- a/lib/ferrum/client/web_socket.rb
+++ b/lib/ferrum/client/web_socket.rb
@@ -141,6 +141,24 @@ def close
         @driver_mutex.synchronize { @driver.close }
       end
 
+      #
+      # Closes the underlying socket whether or not the close handshake ever
+      # completed.
+      #
+      # {#close} only sends a close frame; the socket itself is closed by
+      # {#on_close}, which runs when the browser answers with a close frame of
+      # its own. A browser that is already dead never answers, so without this
+      # the socket stays open until GC finalizes it -- long enough to exhaust
+      # the process's file descriptors when browsers are restarted in a loop.
+      #
+      # @return [void]
+      #
+      def force_close
+        @sock.close unless @sock.closed?
+      rescue IOError, SystemCallError
+        # nop
+      end
+
       private
 
       def start
diff --git a/sig/ferrum/client/web_socket.rbs b/sig/ferrum/client/web_socket.rbs
index bb5338d8..8c31e9a0 100644
--- a/sig/ferrum/client/web_socket.rbs
+++ b/sig/ferrum/client/web_socket.rbs
@@ -30,6 +30,8 @@ module Ferrum
 
       def close: () -> void
 
+      def force_close: () -> void
+
       private
 
       def start: () -> void
diff --git a/spec/client_spec.rb b/spec/client_spec.rb
index b1585041..f3cbbe33 100644
--- a/spec/client_spec.rb
+++ b/spec/client_spec.rb
@@ -38,6 +38,16 @@ def messages
       expect(Ferrum::Utils::ElapsedTime.elapsed_time(start)).to be < 1
     end
 
+    it "closes the socket when the browser dies before answering the close frame" do
+      remote.create_page
+      socket = remote.client.instance_variable_get(:@ws).instance_variable_get(:@sock)
+      Process.kill("KILL", -remote.process.pid)
+
+      remote.quit
+
+      expect(socket).to be_closed
+    end
+
     it "reports an unexpected reader error instead of raising in the main thread" do
       page = remote.create_page
       driver = remote.client.instance_variable_get(:@ws).instance_variable_get(:@driver)