[AOLSERVER-COMMITS] aolserver/nsd nsd.h, 1.118, 1.119 pools.c, 1.11, 1.12 queue.c, 1.43, 1.44

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

Update of /cvsroot/aolserver/aolserver/nsd
In directory sc8-pr-cvs11.sourceforge.net:/tmp/cvs-serv25463

Modified Files:
	nsd.h pools.c queue.c 
Log Message:
Keep track of connection thread state. Two new variables are introduced:
 - starting: keeps the number of currently starting threads
 - waiting: the number of threads in the cond waiting state
These variables help to get a more precise understanding and
allow for better knowlege for thread creation (especially under 
heavy load)


Index: nsd.h
===================================================================
RCS file: /cvsroot/aolserver/aolserver/nsd/nsd.h,v
retrieving revision 1.118
retrieving revision 1.119
diff -C2 -d -r1.118 -r1.119
*** nsd.h	20 Oct 2007 11:57:19 -0000	1.118
--- nsd.h	26 Oct 2007 23:14:17 -0000	1.119
***************
*** 565,568 ****
--- 565,570 ----
      	int 	    	    current;
  	int 	    	    idle;
+ 	int 	    	    waiting;
+ 	int 	    	    starting;
  	int 	    	    timeout;
  	int		    maxconns;

Index: pools.c
===================================================================
RCS file: /cvsroot/aolserver/aolserver/nsd/pools.c,v
retrieving revision 1.11
retrieving revision 1.12
diff -C2 -d -r1.11 -r1.12
*** pools.c	20 Oct 2007 11:57:19 -0000	1.11
--- pools.c	26 Oct 2007 23:14:17 -0000	1.12
***************
*** 185,188 ****
--- 185,201 ----
              }
          }
+         /* catch unsane values */
+         if (poolPtr->threads.max < 1) {
+             Tcl_SetResult(interp, "maxthreads can't be less than 1", TCL_STATIC);
+             return TCL_ERROR;
+         }
+         if (poolPtr->threads.min > poolPtr->threads.max) {
+             Tcl_SetResult(interp, "minthreads can't be larger than maxthreads", TCL_STATIC);
+             return TCL_ERROR;
+         }
+         if (poolPtr->threads.timeout < 1) {
+             Tcl_SetResult(interp, "timeout cannot be less than 1", TCL_STATIC);
+             return TCL_ERROR;
+         }
          if (PoolResult(interp, poolPtr) != TCL_OK) {
              return TCL_ERROR;
***************
*** 480,485 ****
      int i;
  
!     poolPtr->threads.current = poolPtr->threads.idle = poolPtr->threads.min;
      for (i = 0; i < poolPtr->threads.min; ++i) {
          NsCreateConnThread(poolPtr, 1);
      }
--- 493,503 ----
      int i;
  
!     poolPtr->threads.current = 0;
!     poolPtr->threads.starting = 0;
!     poolPtr->threads.waiting = 0;
!     poolPtr->threads.idle = 0;
! 
      for (i = 0; i < poolPtr->threads.min; ++i) {
+         poolPtr->threads.current ++;
          NsCreateConnThread(poolPtr, 1);
      }

Index: queue.c
===================================================================
RCS file: /cvsroot/aolserver/aolserver/nsd/queue.c,v
retrieving revision 1.43
retrieving revision 1.44
diff -C2 -d -r1.43 -r1.44
*** queue.c	22 Oct 2007 22:56:23 -0000	1.43
--- queue.c	26 Oct 2007 23:14:17 -0000	1.44
***************
*** 179,203 ****
      poolPtr->queue.wait.lastPtr = connPtr;
      connPtr->nextPtr = NULL;
!     if (poolPtr->threads.idle == 0
!             && poolPtr->threads.current < poolPtr->threads.max) {
!         ++poolPtr->threads.idle;
!         ++poolPtr->threads.current;
          create = 1;
      }
  
!     /* 
!        Note that in situations, where the maximum number of 
!        connection threads is reached (poolPtr->threads.idle == 0 and create == 0)
!        the request is queued without resources to process these.
!        One has to take care about processing he entries of the queue, when 
!        resources become available again.
!     */
! 
!     ++poolPtr->queue.wait.num;
!     Ns_MutexUnlock(&poolPtr->lock);
      if (create) {
          NsCreateConnThread(poolPtr, 1);
!     } else {
          Ns_CondSignal(&poolPtr->cond);
      }
  }
--- 179,213 ----
      poolPtr->queue.wait.lastPtr = connPtr;
      connPtr->nextPtr = NULL;
! 
!     if (poolPtr->queue.wait.num > 0
!         && poolPtr->threads.current < poolPtr->threads.max) {
!         /* 
!            Create a new thread if no thread is waiting and the number
!            of currently starting or running threads is below max.
!         */
          create = 1;
      }
  
!     poolPtr->queue.wait.num ++;
!     
      if (create) {
+         poolPtr->threads.current ++;
+         Ns_MutexUnlock(&poolPtr->lock);
          NsCreateConnThread(poolPtr, 1);
!     } else if (poolPtr->threads.waiting > 0) {
!         /*
!           There are threads waiting. Signal to process
!           the request.
!          */
          Ns_CondSignal(&poolPtr->cond);
+         Ns_MutexUnlock(&poolPtr->lock);
+     } else {
+         /* 
+            We might have missed signaling, since we are already using
+            max resources, and no thread is available. In such a case
+            the autorecovery at thread exist has to care to process
+            the outstanding requests 
+         */
+         Ns_MutexUnlock(&poolPtr->lock);
      }
  }
***************
*** 379,382 ****
--- 389,396 ----
  
      Ns_MutexLock(&poolPtr->lock);
+ 
+     poolPtr->threads.starting--;
+     poolPtr->threads.idle++;
+ 
      while (poolPtr->threads.maxconns <= 0 || ncons-- > 0) {
  
***************
*** 385,389 ****
  	 * arrive in the configured timeout period.
  	 */
! 
  	if (poolPtr->threads.current <= poolPtr->threads.min) {
  	    timePtr = NULL;
--- 399,403 ----
  	 * arrive in the configured timeout period.
  	 */
!         
  	if (poolPtr->threads.current <= poolPtr->threads.min) {
  	    timePtr = NULL;
***************
*** 394,398 ****
  	}
  
! 	status = NS_OK;
          while (!poolPtr->shutdown
                 && status == NS_OK
--- 408,412 ----
  	}
  
!         status = NS_OK;
          while (!poolPtr->shutdown
                 && status == NS_OK
***************
*** 401,405 ****
--- 415,421 ----
                 nothing is queued, we wait for a queue entry 
              */
+             poolPtr->threads.waiting++;
              status = Ns_CondTimedWait(&poolPtr->cond, &poolPtr->lock, timePtr);
+             poolPtr->threads.waiting--;
          }
  
***************
*** 420,510 ****
  	connPtr->nextPtr = NULL;
  	connPtr->prevPtr = poolPtr->queue.active.lastPtr;
! 	if (poolPtr->queue.active.lastPtr != NULL) {
! 	    poolPtr->queue.active.lastPtr->nextPtr = connPtr;
! 	}
! 	poolPtr->queue.active.lastPtr = connPtr;
! 	if (poolPtr->queue.active.firstPtr == NULL) {
! 	    poolPtr->queue.active.firstPtr = connPtr;
! 	}
! 	poolPtr->threads.idle--;
! 	poolPtr->queue.wait.num--;
!         Ns_MutexUnlock(&poolPtr->lock);
! 
! 	/*
! 	 * Run the connection.
! 	 */
! 
! 	Ns_MutexLock(&connlock);
!         dataPtr->connPtr = connPtr;
! 	Ns_MutexUnlock(&connlock);
  
! 	Ns_GetTime(&connPtr->times.run);
!         ConnRun(connPtr);
  
! 	Ns_MutexLock(&connlock);
!         dataPtr->connPtr = NULL;
! 	Ns_MutexUnlock(&connlock);
  
! 	/*
! 	 * Remove from the active list and push on the free list.
! 	 */
  
!         Ns_MutexLock(&poolPtr->lock);
! 	if (connPtr->prevPtr != NULL) {
! 	    connPtr->prevPtr->nextPtr = connPtr->nextPtr;
! 	} else {
! 	    poolPtr->queue.active.firstPtr = connPtr->nextPtr;
! 	}
! 	if (connPtr->nextPtr != NULL) {
! 	    connPtr->nextPtr->prevPtr = connPtr->prevPtr;
! 	} else {
! 	    poolPtr->queue.active.lastPtr = connPtr->prevPtr;
! 	}
! 	poolPtr->threads.idle++;
!         Ns_MutexUnlock(&poolPtr->lock);
!         NsFreeConn(connPtr);
!         Ns_MutexLock(&poolPtr->lock);
      }
! 
      /*
       * Append this thread to list of threads to reap.
       */
! 
      Ns_MutexLock(&joinlock);
      dataPtr->nextPtr = joinPtr;
      joinPtr = dataPtr;
      Ns_MutexUnlock(&joinlock);
! 
      /*
       * Mark this thread as no longer active.
       */
! 
      if (poolPtr->shutdown) {
! 	msg = "shutdown pending";
      }
-     poolPtr->threads.idle--;
      poolPtr->threads.current--;
!     if (poolPtr->threads.current == 0) {
!         Ns_CondBroadcast(&poolPtr->cond);
!     }
! 
      
!     if (((poolPtr->queue.wait.num > 0 && poolPtr->threads.idle == 0)
           || (poolPtr->threads.current < poolPtr->threads.min)
           ) && !poolPtr->shutdown) {
          /* 
!            We are either exiting from a thread in a situation, where more
!            queue entries are still waiting, or
!            we have less than minthreads connection threads alive.
!            In these situations recreate a connection thread.
          */
!         poolPtr->threads.current++;
!         poolPtr->threads.idle++;
          Ns_MutexUnlock(&poolPtr->lock);
          NsCreateConnThread(poolPtr, 0); /* joinThreads == 0 to avoid deadlock */
      } else {
          Ns_MutexUnlock(&poolPtr->lock);
      }
! 
      Ns_Log(Notice, "exiting: %s", msg);
      Ns_ThreadExit(dataPtr);
--- 436,530 ----
  	connPtr->nextPtr = NULL;
  	connPtr->prevPtr = poolPtr->queue.active.lastPtr;
!          if (poolPtr->queue.active.lastPtr != NULL) {
!              poolPtr->queue.active.lastPtr->nextPtr = connPtr;
!          }
!          poolPtr->queue.active.lastPtr = connPtr;
!          if (poolPtr->queue.active.firstPtr == NULL) {
!              poolPtr->queue.active.firstPtr = connPtr;
!          }
!          poolPtr->threads.idle--;
!          poolPtr->queue.wait.num--;
  
!          Ns_MutexUnlock(&poolPtr->lock);
  
!          /*
!           * Run the connection.
!           */
  
!          Ns_MutexLock(&connlock);
!          dataPtr->connPtr = connPtr;
!          Ns_MutexUnlock(&connlock);
!          
!          Ns_GetTime(&connPtr->times.run);
!          ConnRun(connPtr);
!          Ns_MutexLock(&connlock);
!          dataPtr->connPtr = NULL;
!          Ns_MutexUnlock(&connlock);
!          
!          /*
!           * Remove from the active list and push on the free list.
!           */
  
!          Ns_MutexLock(&poolPtr->lock);
!          if (connPtr->prevPtr != NULL) {
!              connPtr->prevPtr->nextPtr = connPtr->nextPtr;
!          } else {
!              poolPtr->queue.active.firstPtr = connPtr->nextPtr;
!          }
!          if (connPtr->nextPtr != NULL) {
!              connPtr->nextPtr->prevPtr = connPtr->prevPtr;
!          } else {
!              poolPtr->queue.active.lastPtr = connPtr->prevPtr;
!          }
!          poolPtr->threads.idle++;
!          Ns_MutexUnlock(&poolPtr->lock);
!          NsFreeConn(connPtr);
!          Ns_MutexLock(&poolPtr->lock);
      }
!     
      /*
       * Append this thread to list of threads to reap.
       */
!     
      Ns_MutexLock(&joinlock);
      dataPtr->nextPtr = joinPtr;
      joinPtr = dataPtr;
      Ns_MutexUnlock(&joinlock);
!     
      /*
       * Mark this thread as no longer active.
       */
!     
      if (poolPtr->shutdown) {
!         msg = "shutdown pending";
      }
      poolPtr->threads.current--;
!     poolPtr->threads.idle--;
      
!     if (((poolPtr->queue.wait.num > 0 
!           && poolPtr->threads.idle == 0 
!           && poolPtr->threads.starting == 0
!           )
           || (poolPtr->threads.current < poolPtr->threads.min)
           ) && !poolPtr->shutdown) {
          /* 
!            Recreate a thread when on of the condings hold
!            - there are more queue entries are still waiting, 
!            but no thread is either starting or idle, or
!            - there are less than minthreads connection threads alive.
          */
!         poolPtr->threads.current ++;
          Ns_MutexUnlock(&poolPtr->lock);
          NsCreateConnThread(poolPtr, 0); /* joinThreads == 0 to avoid deadlock */
+     } else if (poolPtr->queue.wait.num > 0 && poolPtr->threads.waiting > 0) {
+         /*
+           Wake up a waiting thread
+         */
+         Ns_CondSignal(&poolPtr->cond);
+         Ns_MutexUnlock(&poolPtr->lock);
      } else {
          Ns_MutexUnlock(&poolPtr->lock);
      }
!     
      Ns_Log(Notice, "exiting: %s", msg);
      Ns_ThreadExit(dataPtr);
***************
*** 669,672 ****
--- 689,695 ----
      dataPtr->poolPtr = poolPtr;
      dataPtr->connPtr = NULL;
+     Ns_MutexLock(&poolPtr->lock);
+     poolPtr->threads.starting ++;
+     Ns_MutexUnlock(&poolPtr->lock);
      Ns_ThreadCreate(NsConnThread, dataPtr, 0, &dataPtr->thread);
  }