From aa3259c10ecd519f71ba65df91c976af4f735733 Mon Sep 17 00:00:00 2001
From: Alexander Polcyn <apolcyn@google.com>
Date: Wed, 17 Oct 2018 15:42:47 -0700
Subject: Fix corruption of blocking_resolve_address when ares is used and grpc
 is restarted

---
 .../filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc   | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc b/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
index dfa52867d8..c2a4d42203 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
@@ -473,7 +473,9 @@ void grpc_resolver_dns_ares_init() {
       GRPC_LOG_IF_ERROR("ares_library_init() failed", error);
       return;
     }
-    default_resolver = grpc_resolve_address_impl;
+    if (default_resolver == nullptr) {
+      default_resolver = grpc_resolve_address_impl;
+    }
     grpc_set_resolver_impl(&ares_resolver);
     grpc_core::ResolverRegistry::Builder::RegisterResolverFactory(
         grpc_core::UniquePtr<grpc_core::ResolverFactory>(
-- 
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