Dont use static fields to keep track of locks

src/Hangfire.MemoryStorage/MemoryStorage.cs

@@ -9,6 +9,9 @@ public class MemoryStorage : JobStorage
     {
         private readonly MemoryStorageOptions _options;
 
+        private readonly object _connectionLock = new object();
+        private MemoryStorageConnection _connection;
+
         public Data Data { get; }
 
         public MemoryStorage() : this(new MemoryStorageOptions(), new Data())
@@ -27,7 +30,12 @@ public MemoryStorage(MemoryStorageOptions options, Data data)
 
         public override IStorageConnection GetConnection()
         {
-            return new MemoryStorageConnection(Data, _options.FetchNextJobTimeout);
+            lock (_connectionLock)
+            {
+                if (_connection == null)
+                    _connection = new MemoryStorageConnection(Data, _options.FetchNextJobTimeout);
+            }
+            return _connection;
         }
 
         public override IMonitoringApi GetMonitoringApi()

src/Hangfire.MemoryStorage/MemoryStorageConnection.cs

@@ -15,19 +15,18 @@ namespace Hangfire.MemoryStorage
 {
     public class MemoryStorageConnection : JobStorageConnection
     {
-        private static readonly object FetchJobsLock = new object();
+        private readonly object FetchJobsLock = new object();
         private readonly TimeSpan _fetchNextJobTimeout;
         private readonly Data _data;
-        private static readonly ConcurrentDictionary<string, SemaphoreSlim> _locks = new ConcurrentDictionary<string, SemaphoreSlim>();
+        private readonly ConcurrentDictionary<string, SemaphoreSlim> _locks = new ConcurrentDictionary<string, SemaphoreSlim>();
+        private readonly AutoResetEvent _newItemInQueueEvent = new AutoResetEvent(true);
 
         public MemoryStorageConnection(Data data, TimeSpan fetchNextJobTimeout)
         {
             _fetchNextJobTimeout = fetchNextJobTimeout;
             _data = data;
         }
 
-        internal static readonly AutoResetEvent NewItemInQueueEvent = new AutoResetEvent(true);
-
         public override IDisposable AcquireDistributedLock(string resource, TimeSpan timeout)
         {
             // try to acquire an existing lock or create a new one if none exists for the resource
@@ -102,7 +101,7 @@ public override string CreateExpiredJob(Job job, IDictionary<string, string> par
 
         public override IWriteOnlyTransaction CreateWriteTransaction()
         {
-            return new MemoryStorageWriteOnlyTransaction(_data, NewItemInQueueEvent);
+            return new MemoryStorageWriteOnlyTransaction(_data, _newItemInQueueEvent);
         }
 
         public override IFetchedJob FetchNextJob(string[] queues, CancellationToken cancellationToken)
@@ -139,7 +138,7 @@ orderby q.AddedAt descending
                     }
                 }
 
-                WaitHandle.WaitAny(new[] { cancellationToken.WaitHandle, NewItemInQueueEvent }, TimeSpan.FromSeconds(15));
+                WaitHandle.WaitAny(new[] { cancellationToken.WaitHandle, _newItemInQueueEvent }, TimeSpan.FromSeconds(15));
                 cancellationToken.ThrowIfCancellationRequested();
             }