From 22855def275e7b9187bcd2148e98573051edfc98 Mon Sep 17 00:00:00 2001
From: Stephen Akridge <stephen@solana.com>
Date: Thu, 7 Mar 2019 10:58:32 -0800
Subject: [PATCH] Fix race condition in store.

Multiple threads can enter the read lock and
all store the new empty set to account_maps.
Check again after taking write lock to make sure
only one thread actually inserts the new entry.
---
 runtime/src/accounts.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/runtime/src/accounts.rs b/runtime/src/accounts.rs
index 5eb3857ae3..3342a18187 100644
--- a/runtime/src/accounts.rs
+++ b/runtime/src/accounts.rs
@@ -513,7 +513,9 @@ impl AccountsDB {
                 .contains_key(&pubkey)
             {
                 let mut waccount_maps = self.account_index.account_maps.write().unwrap();
-                waccount_maps.insert(*pubkey, RwLock::new(HashMap::new()));
+                if !waccount_maps.contains_key(&pubkey) {
+                    waccount_maps.insert(*pubkey, RwLock::new(HashMap::new()));
+                }
             }
         }
         self.store_account(fork, pubkey, account);