diff --git a/src/atomicvar.h b/src/atomicvar.h
index 4aa8fa17..84a5bbc5 100644
--- a/src/atomicvar.h
+++ b/src/atomicvar.h
@@ -3,18 +3,29 @@
  *
  * The exported interaface is composed of three macros:
  *
- * atomicIncr(var,count,mutex) -- Increment the atomic counter
- * atomicDecr(var,count,mutex) -- Decrement the atomic counter
- * atomicGet(var,dstvar,mutex) -- Fetch the atomic counter value
+ * atomicIncr(var,count) -- Increment the atomic counter
+ * atomicGetIncr(var,oldvalue_var,count) -- Get and increment the atomic counter
+ * atomicDecr(var,count) -- Decrement the atomic counter
+ * atomicGet(var,dstvar) -- Fetch the atomic counter value
+ * atomicSet(var,value)  -- Set the atomic counter value
+ *
+ * The variable 'var' should also have a declared mutex with the same
+ * name and the "_mutex" postfix, for instance:
+ *
+ *  long myvar;
+ *  pthread_mutex_t myvar_mutex;
+ *  atomicSet(myvar,12345);
  *
  * If atomic primitives are availble (tested in config.h) the mutex
  * is not used.
  *
- * Never use return value from the macros. To update and get use instead:
+ * Never use return value from the macros, instead use the AtomicGetIncr()
+ * if you need to get the current value and increment it atomically, like
+ * in the followign example:
  *
- *  atomicIncr(mycounter,...);
- *  atomicGet(mycounter,newvalue);
- *  doSomethingWith(newvalue);
+ *  long oldvalue;
+ *  atomicGetIncr(myvar,oldvalue,1);
+ *  doSomethingWith(oldvalue);
  *
  * ----------------------------------------------------------------------------
  *
@@ -51,44 +62,72 @@
 #ifndef __ATOMIC_VAR_H
 #define __ATOMIC_VAR_H
 
-#if defined(__ATOMIC_RELAXED) && (!defined(__clang__) || !defined(__APPLE__) || __apple_build_version__ > 4210057)
+/* To test Redis with Helgrind (a Valgrind tool) it is useful to define
+ * the following macro, so that __sync macros are used: those can be detected
+ * by Helgrind (even if they are less efficient) so that no false positive
+ * is reported. */
+// #define __ATOMIC_VAR_FORCE_SYNC_MACROS
+
+#if !defined(__ATOMIC_VAR_FORCE_SYNC_MACROS) && defined(__ATOMIC_RELAXED) && !defined(__sun) && (!defined(__clang__) || !defined(__APPLE__) || __apple_build_version__ > 4210057)
 /* Implementation using __atomic macros. */
 
-#define atomicIncr(var,count,mutex) __atomic_add_fetch(&var,(count),__ATOMIC_RELAXED)
-#define atomicDecr(var,count,mutex) __atomic_sub_fetch(&var,(count),__ATOMIC_RELAXED)
-#define atomicGet(var,dstvar,mutex) do { \
+#define atomicIncr(var,count) __atomic_add_fetch(&var,(count),__ATOMIC_RELAXED)
+#define atomicGetIncr(var,oldvalue_var,count) do { \
+    oldvalue_var = __atomic_fetch_add(&var,(count),__ATOMIC_RELAXED); \
+} while(0)
+#define atomicDecr(var,count) __atomic_sub_fetch(&var,(count),__ATOMIC_RELAXED)
+#define atomicGet(var,dstvar) do { \
     dstvar = __atomic_load_n(&var,__ATOMIC_RELAXED); \
 } while(0)
+#define atomicSet(var,value) __atomic_store_n(&var,value,__ATOMIC_RELAXED)
+#define REDIS_ATOMIC_API "atomic-builtin"
 
 #elif defined(HAVE_ATOMIC)
 /* Implementation using __sync macros. */
 
-#define atomicIncr(var,count,mutex) __sync_add_and_fetch(&var,(count))
-#define atomicDecr(var,count,mutex) __sync_sub_and_fetch(&var,(count))
-#define atomicGet(var,dstvar,mutex) do { \
+#define atomicIncr(var,count) __sync_add_and_fetch(&var,(count))
+#define atomicGetIncr(var,oldvalue_var,count) do { \
+    oldvalue_var = __sync_fetch_and_add(&var,(count)); \
+} while(0)
+#define atomicDecr(var,count) __sync_sub_and_fetch(&var,(count))
+#define atomicGet(var,dstvar) do { \
     dstvar = __sync_sub_and_fetch(&var,0); \
 } while(0)
+#define atomicSet(var,value) do { \
+    while(!__sync_bool_compare_and_swap(&var,var,value)); \
+} while(0)
+#define REDIS_ATOMIC_API "sync-builtin"
 
 #else
 /* Implementation using pthread mutex. */
 
-#define atomicIncr(var,count,mutex) do { \
-    pthread_mutex_lock(&mutex); \
+#define atomicIncr(var,count) do { \
+    pthread_mutex_lock(&var ## _mutex); \
     var += (count); \
-    pthread_mutex_unlock(&mutex); \
+    pthread_mutex_unlock(&var ## _mutex); \
 } while(0)
-
-#define atomicDecr(var,count,mutex) do { \
-    pthread_mutex_lock(&mutex); \
+#define atomicGetIncr(var,oldvalue_var,count) do { \
+    pthread_mutex_lock(&var ## _mutex); \
+    oldvalue_var = var; \
+    var += (count); \
+    pthread_mutex_unlock(&var ## _mutex); \
+} while(0)
+#define atomicDecr(var,count) do { \
+    pthread_mutex_lock(&var ## _mutex); \
     var -= (count); \
-    pthread_mutex_unlock(&mutex); \
+    pthread_mutex_unlock(&var ## _mutex); \
 } while(0)
-
-#define atomicGet(var,dstvar,mutex) do { \
-    pthread_mutex_lock(&mutex); \
+#define atomicGet(var,dstvar) do { \
+    pthread_mutex_lock(&var ## _mutex); \
     dstvar = var; \
-    pthread_mutex_unlock(&mutex); \
+    pthread_mutex_unlock(&var ## _mutex); \
 } while(0)
-#endif
+#define atomicSet(var,value) do { \
+    pthread_mutex_lock(&var ## _mutex); \
+    var = value; \
+    pthread_mutex_unlock(&var ## _mutex); \
+} while(0)
+#define REDIS_ATOMIC_API "pthread-mutex"
 
+#endif
 #endif /* __ATOMIC_VAR_H */
diff --git a/src/http_parser.c b/src/http_parser.c
index 895bf0c7..8d851245 100644
--- a/src/http_parser.c
+++ b/src/http_parser.c
@@ -1,7 +1,4 @@
-/* Based on src/http/ngx_http_parse.c from NGINX copyright Igor Sysoev
- *
- * Additional changes are licensed under the same terms as NGINX and
- * copyright Joyent, Inc. and other Node contributors. All rights reserved.
+/* Copyright Joyent, Inc. and other Node contributors.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to
@@ -286,10 +283,10 @@ enum state
   , s_res_HT
   , s_res_HTT
   , s_res_HTTP
-  , s_res_first_http_major
   , s_res_http_major
-  , s_res_first_http_minor
+  , s_res_http_dot
   , s_res_http_minor
+  , s_res_http_end
   , s_res_first_status_code
   , s_res_status_code
   , s_res_status_start
@@ -316,10 +313,10 @@ enum state
   , s_req_http_HT
   , s_req_http_HTT
   , s_req_http_HTTP
-  , s_req_first_http_major
   , s_req_http_major
-  , s_req_first_http_minor
+  , s_req_http_dot
   , s_req_http_minor
+  , s_req_http_end
   , s_req_line_almost_done
 
   , s_header_field_start
@@ -795,75 +792,48 @@ size_t http_parser_execute (http_parser *parser,
 
       case s_res_HTTP:
         STRICT_CHECK(ch != '/');
-        UPDATE_STATE(s_res_first_http_major);
+        UPDATE_STATE(s_res_http_major);
         break;
 
-      case s_res_first_http_major:
-        if (UNLIKELY(ch < '0' || ch > '9')) {
+      case s_res_http_major:
+        if (UNLIKELY(!IS_NUM(ch))) {
           SET_ERRNO(HPE_INVALID_VERSION);
           goto error;
         }
 
         parser->http_major = ch - '0';
-        UPDATE_STATE(s_res_http_major);
+        UPDATE_STATE(s_res_http_dot);
         break;
 
-      /* major HTTP version or dot */
-      case s_res_http_major:
+      case s_res_http_dot:
       {
-        if (ch == '.') {
-          UPDATE_STATE(s_res_first_http_minor);
-          break;
-        }
-
-        if (!IS_NUM(ch)) {
-          SET_ERRNO(HPE_INVALID_VERSION);
-          goto error;
-        }
-
-        parser->http_major *= 10;
-        parser->http_major += ch - '0';
-
-        if (UNLIKELY(parser->http_major > 999)) {
+        if (UNLIKELY(ch != '.')) {
           SET_ERRNO(HPE_INVALID_VERSION);
           goto error;
         }
 
+        UPDATE_STATE(s_res_http_minor);
         break;
       }
 
-      /* first digit of minor HTTP version */
-      case s_res_first_http_minor:
+      case s_res_http_minor:
         if (UNLIKELY(!IS_NUM(ch))) {
           SET_ERRNO(HPE_INVALID_VERSION);
           goto error;
         }
 
         parser->http_minor = ch - '0';
-        UPDATE_STATE(s_res_http_minor);
+        UPDATE_STATE(s_res_http_end);
         break;
 
-      /* minor HTTP version or end of request line */
-      case s_res_http_minor:
+      case s_res_http_end:
       {
-        if (ch == ' ') {
-          UPDATE_STATE(s_res_first_status_code);
-          break;
-        }
-
-        if (UNLIKELY(!IS_NUM(ch))) {
-          SET_ERRNO(HPE_INVALID_VERSION);
-          goto error;
-        }
-
-        parser->http_minor *= 10;
-        parser->http_minor += ch - '0';
-
-        if (UNLIKELY(parser->http_minor > 999)) {
+        if (UNLIKELY(ch != ' ')) {
           SET_ERRNO(HPE_INVALID_VERSION);
           goto error;
         }
 
+        UPDATE_STATE(s_res_first_status_code);
         break;
       }
 
@@ -890,10 +860,9 @@ size_t http_parser_execute (http_parser *parser,
               UPDATE_STATE(s_res_status_start);
               break;
             case CR:
-              UPDATE_STATE(s_res_line_almost_done);
-              break;
             case LF:
-              UPDATE_STATE(s_header_field_start);
+              UPDATE_STATE(s_res_status_start);
+              REEXECUTE();
               break;
             default:
               SET_ERRNO(HPE_INVALID_STATUS);
@@ -915,19 +884,13 @@ size_t http_parser_execute (http_parser *parser,
 
       case s_res_status_start:
       {
-        if (ch == CR) {
-          UPDATE_STATE(s_res_line_almost_done);
-          break;
-        }
-
-        if (ch == LF) {
-          UPDATE_STATE(s_header_field_start);
-          break;
-        }
-
         MARK(status);
         UPDATE_STATE(s_res_status);
         parser->index = 0;
+
+        if (ch == CR || ch == LF)
+          REEXECUTE();
+
         break;
       }
 
@@ -1007,7 +970,7 @@ size_t http_parser_execute (http_parser *parser,
           UPDATE_STATE(s_req_spaces_before_url);
         } else if (ch == matcher[parser->index]) {
           ; /* nada */
-        } else if (IS_ALPHA(ch)) {
+        } else if ((ch >= 'A' && ch <= 'Z') || ch == '-') {
 
           switch (parser->method << 16 | parser->index << 8 | ch) {
 #define XX(meth, pos, ch, new_meth) \
@@ -1016,31 +979,27 @@ size_t http_parser_execute (http_parser *parser,
 
             XX(POST,      1, 'U', PUT)
             XX(POST,      1, 'A', PATCH)
+            XX(POST,      1, 'R', PROPFIND)
+            XX(PUT,       2, 'R', PURGE)
             XX(CONNECT,   1, 'H', CHECKOUT)
             XX(CONNECT,   2, 'P', COPY)
             XX(MKCOL,     1, 'O', MOVE)
             XX(MKCOL,     1, 'E', MERGE)
+            XX(MKCOL,     1, '-', MSEARCH)
             XX(MKCOL,     2, 'A', MKACTIVITY)
             XX(MKCOL,     3, 'A', MKCALENDAR)
             XX(SUBSCRIBE, 1, 'E', SEARCH)
             XX(REPORT,    2, 'B', REBIND)
-            XX(POST,      1, 'R', PROPFIND)
             XX(PROPFIND,  4, 'P', PROPPATCH)
-            XX(PUT,       2, 'R', PURGE)
             XX(LOCK,      1, 'I', LINK)
             XX(UNLOCK,    2, 'S', UNSUBSCRIBE)
             XX(UNLOCK,    2, 'B', UNBIND)
             XX(UNLOCK,    3, 'I', UNLINK)
 #undef XX
-
             default:
               SET_ERRNO(HPE_INVALID_METHOD);
               goto error;
           }
-        } else if (ch == '-' &&
-                   parser->index == 1 &&
-                   parser->method == HTTP_MKCOL) {
-          parser->method = HTTP_MSEARCH;
         } else {
           SET_ERRNO(HPE_INVALID_METHOD);
           goto error;
@@ -1153,57 +1112,41 @@ size_t http_parser_execute (http_parser *parser,
 
       case s_req_http_HTTP:
         STRICT_CHECK(ch != '/');
-        UPDATE_STATE(s_req_first_http_major);
-        break;
-
-      /* first digit of major HTTP version */
-      case s_req_first_http_major:
-        if (UNLIKELY(ch < '1' || ch > '9')) {
-          SET_ERRNO(HPE_INVALID_VERSION);
-          goto error;
-        }
-
-        parser->http_major = ch - '0';
         UPDATE_STATE(s_req_http_major);
         break;
 
-      /* major HTTP version or dot */
       case s_req_http_major:
-      {
-        if (ch == '.') {
-          UPDATE_STATE(s_req_first_http_minor);
-          break;
-        }
-
         if (UNLIKELY(!IS_NUM(ch))) {
           SET_ERRNO(HPE_INVALID_VERSION);
           goto error;
         }
 
-        parser->http_major *= 10;
-        parser->http_major += ch - '0';
+        parser->http_major = ch - '0';
+        UPDATE_STATE(s_req_http_dot);
+        break;
 
-        if (UNLIKELY(parser->http_major > 999)) {
+      case s_req_http_dot:
+      {
+        if (UNLIKELY(ch != '.')) {
           SET_ERRNO(HPE_INVALID_VERSION);
           goto error;
         }
 
+        UPDATE_STATE(s_req_http_minor);
         break;
       }
 
-      /* first digit of minor HTTP version */
-      case s_req_first_http_minor:
+      case s_req_http_minor:
         if (UNLIKELY(!IS_NUM(ch))) {
           SET_ERRNO(HPE_INVALID_VERSION);
           goto error;
         }
 
         parser->http_minor = ch - '0';
-        UPDATE_STATE(s_req_http_minor);
+        UPDATE_STATE(s_req_http_end);
         break;
 
-      /* minor HTTP version or end of request line */
-      case s_req_http_minor:
+      case s_req_http_end:
       {
         if (ch == CR) {
           UPDATE_STATE(s_req_line_almost_done);
@@ -1215,21 +1158,8 @@ size_t http_parser_execute (http_parser *parser,
           break;
         }
 
-        /* XXX allow spaces after digit? */
-
-        if (UNLIKELY(!IS_NUM(ch))) {
-          SET_ERRNO(HPE_INVALID_VERSION);
-          goto error;
-        }
-
-        parser->http_minor *= 10;
-        parser->http_minor += ch - '0';
-
-        if (UNLIKELY(parser->http_minor > 999)) {
-          SET_ERRNO(HPE_INVALID_VERSION);
-          goto error;
-        }
-
+        SET_ERRNO(HPE_INVALID_VERSION);
+        goto error;
         break;
       }
 
@@ -1794,10 +1724,17 @@ size_t http_parser_execute (http_parser *parser,
         UPDATE_STATE(s_headers_done);
 
         /* Set this here so that on_headers_complete() callbacks can see it */
-        parser->upgrade =
-          ((parser->flags & (F_UPGRADE | F_CONNECTION_UPGRADE)) ==
-           (F_UPGRADE | F_CONNECTION_UPGRADE) ||
-           parser->method == HTTP_CONNECT);
+        if ((parser->flags & F_UPGRADE) &&
+            (parser->flags & F_CONNECTION_UPGRADE)) {
+          /* For responses, "Upgrade: foo" and "Connection: upgrade" are
+           * mandatory only when it is a 101 Switching Protocols response,
+           * otherwise it is purely informational, to announce support.
+           */
+          parser->upgrade =
+              (parser->type == HTTP_REQUEST || parser->status_code == 101);
+        } else {
+          parser->upgrade = (parser->method == HTTP_CONNECT);
+        }
 
         /* Here we call the headers_complete callback. This is somewhat
          * different than other callbacks because if the user returns 1, we
@@ -1816,6 +1753,7 @@ size_t http_parser_execute (http_parser *parser,
             case 2:
               parser->upgrade = 1;
 
+            /* FALLTHROUGH */
             case 1:
               parser->flags |= F_SKIPBODY;
               break;
@@ -2375,7 +2313,7 @@ http_parser_parse_url(const char *buf, size_t buflen, int is_connect,
       case s_req_server_with_at:
         found_at = 1;
 
-      /* FALLTROUGH */
+      /* FALLTHROUGH */
       case s_req_server:
         uf = UF_HOST;
         break;
diff --git a/src/http_parser.h b/src/http_parser.h
index 45c72a07..fd2a5641 100644
--- a/src/http_parser.h
+++ b/src/http_parser.h
@@ -29,11 +29,10 @@ extern "C" {
 #define HTTP_PARSER_VERSION_MINOR 7
 #define HTTP_PARSER_VERSION_PATCH 1
 
-#include <sys/types.h>
+#include <stddef.h>
 #if defined(_WIN32) && !defined(__MINGW32__) && \
   (!defined(_MSC_VER) || _MSC_VER<1600) && !defined(__WINE__)
 #include <BaseTsd.h>
-#include <stddef.h>
 typedef __int8 int8_t;
 typedef unsigned __int8 uint8_t;
 typedef __int16 int16_t;
diff --git a/src/zmalloc.c b/src/zmalloc.c
index f71ce2c9..094dd80f 100644
--- a/src/zmalloc.c
+++ b/src/zmalloc.c
@@ -73,25 +73,16 @@ void zlibc_free(void *ptr) {
 #define update_zmalloc_stat_alloc(__n) do { \
     size_t _n = (__n); \
     if (_n&(sizeof(long)-1)) _n += sizeof(long)-(_n&(sizeof(long)-1)); \
-    if (zmalloc_thread_safe) { \
-        atomicIncr(used_memory,__n,used_memory_mutex); \
-    } else { \
-        used_memory += _n; \
-    } \
+    atomicIncr(used_memory,__n); \
 } while(0)
 
 #define update_zmalloc_stat_free(__n) do { \
     size_t _n = (__n); \
     if (_n&(sizeof(long)-1)) _n += sizeof(long)-(_n&(sizeof(long)-1)); \
-    if (zmalloc_thread_safe) { \
-        atomicDecr(used_memory,__n,used_memory_mutex); \
-    } else { \
-        used_memory -= _n; \
-    } \
+    atomicDecr(used_memory,__n); \
 } while(0)
 
 static size_t used_memory = 0;
-static int zmalloc_thread_safe = 0;
 pthread_mutex_t used_memory_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 static void zmalloc_default_oom(size_t size) {
@@ -220,19 +211,10 @@ char *zstrdup(const char *s) {
 
 size_t zmalloc_used_memory(void) {
     size_t um;
-
-    if (zmalloc_thread_safe) {
-        atomicGet(used_memory,um,used_memory_mutex);
-    } else {
-        um = used_memory;
-    }
+    atomicGet(used_memory,um);
     return um;
 }
 
-void zmalloc_enable_thread_safeness(void) {
-    zmalloc_thread_safe = 1;
-}
-
 void zmalloc_set_oom_handler(void (*oom_handler)(size_t)) {
     zmalloc_oom_handler = oom_handler;
 }
@@ -418,8 +400,9 @@ size_t zmalloc_get_memory_size(void) {
     if (sysctl(mib, 2, &size, &len, NULL, 0) == 0)
         return (size_t)size;
     return 0L;          /* Failed? */
-#endif /* sysctl and sysconf variants */
-
+#else
+    return 0L;          /* Unknown method to get the data. */
+#endif
 #else
     return 0L;          /* Unknown OS. */
 #endif
diff --git a/src/zmalloc.h b/src/zmalloc.h
index b6d4e1d9..64f2f36a 100644
--- a/src/zmalloc.h
+++ b/src/zmalloc.h
@@ -78,7 +78,6 @@ void *zrealloc(void *ptr, size_t size);
 void zfree(void *ptr);
 char *zstrdup(const char *s);
 size_t zmalloc_used_memory(void);
-void zmalloc_enable_thread_safeness(void);
 void zmalloc_set_oom_handler(void (*oom_handler)(size_t));
 float zmalloc_get_fragmentation_ratio(size_t rss);
 size_t zmalloc_get_rss(void);