adaptive sleep for ClientCusror::yield SERVER-975

4 files changed, 24 insertions, 0 deletions

diff --git a/db/client.cpp b/db/client.cpp
index dc82a2550da..a2fe5683394 100644
--- a/db/client.cpp
+++ b/db/client.cpp
@@ -245,4 +245,21 @@ namespace mongo {
         return b.obj();
     }
 
+    int Client::recommendedYieldMicros(){
+        int num = 0;
+        {
+            scoped_lock bl(clientsMutex);
+            num = clients.size();
+        }
+        
+        if ( --num <= 0 ) // -- is for myself
+            return 0;
+        
+        if ( num > 50 )
+            num = 50;
+
+        num *= 100;
+        return num;
+    }
+
 }
diff --git a/db/client.h b/db/client.h
index ab4350949b4..c484198219a 100644
--- a/db/client.h
+++ b/db/client.h
@@ -45,6 +45,8 @@ namespace mongo {
         static mongo::mutex clientsMutex;
         static set<Client*> clients; // always be in clientsMutex when manipulating this
 
+        static int recommendedYieldMicros();
+
         class GodScope {
             bool _prev;
         public:
diff --git a/db/clientcursor.cpp b/db/clientcursor.cpp
index be0bd2f232e..1281fc33660 100644
--- a/db/clientcursor.cpp
+++ b/db/clientcursor.cpp
@@ -232,6 +232,7 @@ namespace mongo {
             
         {
             dbtempreleasecond unlock;
+            sleepmicros( Client::recommendedYieldMicros() );
         }
 
         if ( ClientCursor::find( id , false ) == 0 ){
diff --git a/util/goodies.h b/util/goodies.h
index a70f322dfe4..cd5423b344f 100644
--- a/util/goodies.h
+++ b/util/goodies.h
@@ -195,6 +195,8 @@ namespace mongo {
         boost::thread::sleep(xt);
     }
     inline void sleepmicros(int s) {
+        if ( s <= 0 )
+            return;
         boost::xtime xt;
         boost::xtime_get(&xt, boost::TIME_UTC);
         xt.sec += ( s / 1000000 );
@@ -215,6 +217,8 @@ namespace mongo {
         }
     }
     inline void sleepmicros(int s) {
+        if ( s <= 0 )
+            return;
         struct timespec t;
         t.tv_sec = (int)(s / 1000000);
         t.tv_nsec = s % 1000000;