[AOLSERVER-COMMITS] aolserver/nsd pools.c, 1.13, 1.14 nsd.h, 1.119, 1.120 queue.c, 1.45, 1.46

[<gne...@us...>]

Update of /cvsroot/aolserver/aolserver/nsd
In directory 23jxhf1.ch3.sourceforge.com:/tmp/cvs-serv24700/nsd

Modified Files:
	pools.c nsd.h queue.c 
Log Message:

New configure parameter "spread" for ns_pools: 

  Background: Requests are distributed to idle threads via CondSignal,
  which delivers subsequent signals to idle threads in a circular
  manner (i.e. t1, t2, .. tn, then t1 again) determined by the
  scheduling policy of the operating system. This round robin behavior
  has the disadvantage that multiple threads terminate about at the
  same time, based on the maxconnections (or maxconns) value. The idle
  timeout will never be used on a sufficiently busy server.  The mass
  termination of threads is performance-wise bad, especially when many
  connections threads are configured, since it is likely that about
  the same amount of threads will be recreated.

  The "spread" parameter introduces a random factor into threadtimeout
  and maxconnections to avoid these termination cycles.  It adds +/-
  the specified percentage to maxconnections and threadtimeout (e.g. a
  spread of 20 means a random value between 0.80 to 1.20 of the
  specified value of maxconnections and threadtimeout for every
  connection thread).
  


Index: pools.c
===================================================================
RCS file: /cvsroot/aolserver/aolserver/nsd/pools.c,v
retrieving revision 1.13
retrieving revision 1.14
diff -C2 -d -r1.13 -r1.14
*** pools.c	5 Dec 2008 08:51:43 -0000	1.13
--- pools.c	27 Dec 2008 00:36:38 -0000	1.14
***************
*** 120,127 ****
      } opt;
      static CONST char *cfgs[] = {
!         "-maxthreads", "-minthreads", "-maxconns", "-timeout", NULL
      };
      enum {
!         PCMaxThreadsIdx, PCMinThreadsIdx, PCMaxConnsIdx, PCTimeoutIdx
      } cfg;
  
--- 120,127 ----
      } opt;
      static CONST char *cfgs[] = {
!         "-maxthreads", "-minthreads", "-maxconns", "-timeout", "-spread", NULL
      };
      enum {
!         PCMaxThreadsIdx, PCMinThreadsIdx, PCMaxConnsIdx, PCTimeoutIdx, PCSpreadIdx
      } cfg;
  
***************
*** 183,186 ****
--- 183,190 ----
                  poolPtr->threads.maxconns = val;
                  break;
+ 
+             case PCSpreadIdx:
+                 poolPtr->threads.spread = val;
+                 break;
              }
          }
***************
*** 198,201 ****
--- 202,213 ----
              return TCL_ERROR;
          }
+         if (poolPtr->threads.maxconns < 1) {
+             Tcl_SetResult(interp, "maxconns cannot be less than 1", TCL_STATIC);
+             return TCL_ERROR;
+         }
+         if (poolPtr->threads.spread < 0 || poolPtr->threads.spread > 100 ) {
+             Tcl_SetResult(interp, "spread must be between 0 and 100", TCL_STATIC);
+             return TCL_ERROR;
+         }
          if (PoolResult(interp, poolPtr) != TCL_OK) {
              return TCL_ERROR;
***************
*** 391,394 ****
--- 403,407 ----
      	poolPtr->threads.timeout = 120; /* NB: Exit after 2 minutes idle. */
      	poolPtr->threads.maxconns = 0;  /* NB: Never exit thread. */
+     	poolPtr->threads.spread = 20;   /* NB: +-20% random variance on timeout and maxconns. */
     }
      return poolPtr;
***************
*** 421,425 ****
          !AppendPool(interp, "maxconns", poolPtr->threads.maxconns) ||
          !AppendPool(interp, "queued", poolPtr->threads.queued) ||
!         !AppendPool(interp, "timeout", poolPtr->threads.timeout)) {
      	return TCL_ERROR;
      }
--- 434,440 ----
          !AppendPool(interp, "maxconns", poolPtr->threads.maxconns) ||
          !AppendPool(interp, "queued", poolPtr->threads.queued) ||
!         !AppendPool(interp, "timeout", poolPtr->threads.timeout) ||
!         !AppendPool(interp, "spread", poolPtr->threads.spread)
!       ) {
      	return TCL_ERROR;
      }

Index: nsd.h
===================================================================
RCS file: /cvsroot/aolserver/aolserver/nsd/nsd.h,v
retrieving revision 1.119
retrieving revision 1.120
diff -C2 -d -r1.119 -r1.120
*** nsd.h	26 Oct 2007 23:14:17 -0000	1.119
--- nsd.h	27 Dec 2008 00:36:38 -0000	1.120
***************
*** 569,572 ****
--- 569,573 ----
  	int 	    	    timeout;
  	int		    maxconns;
+ 	int		    spread;
      	unsigned int	    queued;
      } threads;

Index: queue.c
===================================================================
RCS file: /cvsroot/aolserver/aolserver/nsd/queue.c,v
retrieving revision 1.45
retrieving revision 1.46
diff -C2 -d -r1.45 -r1.46
*** queue.c	24 Sep 2008 11:25:33 -0000	1.45
--- queue.c	27 Dec 2008 00:36:38 -0000	1.46
***************
*** 371,374 ****
--- 371,375 ----
      int              status, ncons;
      char            *msg;
+     double           spread;
      
      /*
***************
*** 381,385 ****
      Ns_MutexUnlock(&poolPtr->lock);
      Ns_ThreadSetName(name);
!     ncons = poolPtr->threads.maxconns;
      msg = "exceeded max connections per thread";
      
--- 382,391 ----
      Ns_MutexUnlock(&poolPtr->lock);
      Ns_ThreadSetName(name);
! 
!     /* spread is a value of 1.0 +- specified percentage, 
!        i.e. between 0.0 and 2.0 when the configured percentage is 100 */
!     spread = 1.0 + (2 * poolPtr->threads.spread * Ns_DRand() - poolPtr->threads.spread) / 100.0;
! 
!     ncons = round(poolPtr->threads.maxconns * spread);
      msg = "exceeded max connections per thread";
      
***************
*** 404,408 ****
  	} else {
  	    Ns_GetTime(&wait);
! 	    Ns_IncrTime(&wait, poolPtr->threads.timeout, 0);
  	    timePtr = &wait;
  	}
--- 410,414 ----
  	} else {
  	    Ns_GetTime(&wait);
! 	    Ns_IncrTime(&wait, round(poolPtr->threads.timeout * spread), 0);
  	    timePtr = &wait;
  	}