Threaded IO: ability to disable reads from threaded path.

src/networking.c

@@ -2723,6 +2723,7 @@ int handleClientsWithPendingWritesUsingThreads(void) {
  * pending read clients and flagged as such. */
 int postponeClientRead(client *c) {
     if (io_threads_active &&
+        server.io_threads_do_reads &&
         !(c->flags & (CLIENT_MASTER|CLIENT_SLAVE|CLIENT_PENDING_READ)))
     {
         c->flags |= CLIENT_PENDING_READ;
@@ -2734,7 +2735,7 @@ int postponeClientRead(client *c) {
 }
 
 int handleClientsWithPendingReadsUsingThreads(void) {
-    if (!io_threads_active) return 0;
+    if (!io_threads_active || !server.io_threads_do_reads) return 0;
     int processed = listLength(server.clients_pending_read);
     if (processed == 0) return 0;
 

src/server.c

@@ -2315,6 +2315,7 @@ void initServerConfig(void) {
     server.always_show_logo = CONFIG_DEFAULT_ALWAYS_SHOW_LOGO;
     server.lua_time_limit = LUA_SCRIPT_TIME_LIMIT;
     server.io_threads_num = CONFIG_DEFAULT_IO_THREADS_NUM;
+    server.io_threads_do_reads = CONFIG_DEFAULT_IO_THREADS_DO_READS;
 
     server.lruclock = getLRUClock();
     resetServerSaveParams();

src/server.h

@@ -88,6 +88,7 @@ typedef long long mstime_t; /* millisecond time type. */
 #define CONFIG_DEFAULT_CLIENT_TIMEOUT       0   /* Default client timeout: infinite */
 #define CONFIG_DEFAULT_DBNUM     16
 #define CONFIG_DEFAULT_IO_THREADS_NUM 1         /* Single threaded by default */
+#define CONFIG_DEFAULT_IO_THREADS_DO_READS 0    /* Read + parse from threads? */
 #define CONFIG_MAX_LINE    1024
 #define CRON_DBS_PER_CALL 16
 #define NET_MAX_WRITES_PER_EVENT (1024*64)
@@ -1069,6 +1070,7 @@ struct redisServer {
     int gopher_enabled;         /* If true the server will reply to gopher
                                    queries. Will still serve RESP2 queries. */
     int io_threads_num;         /* Number of IO threads to use. */
+    int io_threads_do_reads;    /* Read and parse from IO threads? */
 
     /* RDB / AOF loading information */
     int loading;                /* We are loading data from disk if true */