Fixed deadlock in the debugger agent in Windows.

test/cctest/test-debug.cc

Index: test/cctest/test-debug.cc
diff --git a/test/cctest/test-debug.cc b/test/cctest/test-debug.cc
index de60d4999ded690f22ce0c14b5b077d3bdbe41cf..2383f2dd09fb9926ebe5cbc4078290b4c9348585 100644
--- a/test/cctest/test-debug.cc
+++ b/test/cctest/test-debug.cc
@@ -5845,11 +5845,14 @@ TEST(DebuggerAgent) {
   const int kPort1 = 5858;
   const int kPort2 = 5857;
   const int kPort3 = 5856;
+  const int kPort4 = 5855;
 
   // Make a string with the port2 number.
   const int kPortBufferLen = 6;
   char port2_str[kPortBufferLen];
   OS::SNPrintF(i::Vector<char>(port2_str, kPortBufferLen), "%d", kPort2);
+  char port4_str[kPortBufferLen];
+  OS::SNPrintF(i::Vector<char>(port4_str, kPortBufferLen), "%d", kPort4);
 
   bool ok;
 
@@ -5885,6 +5888,27 @@ TEST(DebuggerAgent) {
   debugger->StopAgent();
 
   delete server;
+
+  // Test responsiveness after connecting and disconnecting a client.
+  ok = debugger->StartAgent("test", kPort4);
+  CHECK(ok);
+  client = i::OS::CreateSocket();
+  ok = client->Connect("localhost", port4_str);
+  CHECK(ok);
+  ok = client->Receive(&buf, 1) == 1;
+  CHECK(ok);
+  ok = client->Send(
+      "{\"seq\":1,\"type\":\"request\",\"command\":\"disconnect\"}", 49);
+  CHECK(ok);
+  client->Shutdown();
+  delete client;
+  // Is the server still responsive?
+  client = i::OS::CreateSocket();
+  ok = client->Connect("localhost", port4_str);
+  CHECK(ok);
+  client->Shutdown();
+  delete client;
+  debugger->StopAgent();
 }