From e0e1fe4f89e38582ec0d6997bbdb6fe28cee9700 Mon Sep 17 00:00:00 2001
From: Alastair Crabtree <alastair.crabtree@bbc.com>
Date: Mon, 21 Sep 2020 21:23:47 +0100
Subject: [PATCH] task: size of the key locks array should be at least 32, and
 larger if you have a lot of CPUs

---
 LazyCache/CachingService.cs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/LazyCache/CachingService.cs b/LazyCache/CachingService.cs
index 84d5bf8..389ddcd 100644
--- a/LazyCache/CachingService.cs
+++ b/LazyCache/CachingService.cs
@@ -13,7 +13,7 @@ public class CachingService : IAppCache
     {
         private readonly Lazy<ICacheProvider> cacheProvider;
 
-        private readonly int[] keyLocks = new int[32];
+        private readonly int[] keyLocks;
 
         public CachingService() : this(DefaultCacheProvider)
         {
@@ -22,12 +22,17 @@ public CachingService() : this(DefaultCacheProvider)
         public CachingService(Lazy<ICacheProvider> cacheProvider)
         {
             this.cacheProvider = cacheProvider ?? throw new ArgumentNullException(nameof(cacheProvider));
+            var lockCount = Math.Max(Environment.ProcessorCount * 8, 32);
+            keyLocks = new int[lockCount];
         }
 
         public CachingService(Func<ICacheProvider> cacheProviderFactory)
         {
             if (cacheProviderFactory == null) throw new ArgumentNullException(nameof(cacheProviderFactory));
             cacheProvider = new Lazy<ICacheProvider>(cacheProviderFactory);
+            var lockCount = Math.Max(Environment.ProcessorCount * 8, 32);
+            keyLocks = new int[lockCount];
+
         }
 
         public CachingService(ICacheProvider cache) : this(() => cache)