--- IO-AIO/AIO.xs	2006/10/28 00:17:30	1.83
+++ IO-AIO/AIO.xs	2006/10/28 01:24:19	1.84
@@ -45,6 +45,9 @@
 # endif
 #endif
 
+/* number of seconds after which idle threads exit */
+#define IDLE_TIMEOUT 10
+
 /* used for struct dirent, AIX doesn't provide it */
 #ifndef NAME_MAX
 # define NAME_MAX 4096
@@ -146,7 +149,7 @@
 
 static int next_pri = DEFAULT_PRI + PRI_BIAS;
 
-static unsigned int started, wanted;
+static unsigned int started, idle, wanted;
 
 #if __linux && defined (PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP)
 # define AIO_MUTEX_INIT PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
@@ -198,6 +201,7 @@
 }
 
 static volatile unsigned int nreqs, nready, npending;
+static volatile unsigned int max_idle = 4;
 static volatile unsigned int max_outstanding = 0xffffffff;
 static int respipe [2];
 
@@ -558,35 +562,13 @@
 
 static void maybe_start_thread ()
 {
-#if 0
-  static struct timeval last;
-  struct timeval diff, now;
-#endif
-
   if (started >= wanted)
     return;
   
-  if (nready <= nreqs - get_nready () - get_npending ())
+  /* todo: maybe use idle here, but might be less exact */
+  if ((int)nready <= (int)started - (int)(nreqs - get_nready () - get_npending ()))
     return;
 
-#if 0
-  gettimeofday (&now, 0);
-
-  diff.tv_sec  = now.tv_sec  - last.tv_sec;
-  diff.tv_usec = now.tv_usec - last.tv_usec;
-
-  if (diff.tv_usec < 0)
-    {
-      --diff.tv_sec;
-      diff.tv_usec += 1000000;
-    }
-
-  if (!diff.tv_sec && diff.tv_usec < 10000)
-    return;
-
-  last = now;
-#endif
-
   start_thread ();
 }
 
@@ -1006,10 +988,17 @@
 static void *aio_proc (void *thr_arg)
 {
   aio_req req;
+  struct timespec ts;
   worker *self = (worker *)thr_arg;
 
+  /* try to distribute timeouts somewhat evenly */
+  ts.tv_nsec = (((unsigned long)self + (unsigned long)ts.tv_sec) & 1023UL)
+               * (1000000000UL / 1024UL);
+
   for (;;)
     {
+      ts.tv_sec  = time (0) + IDLE_TIMEOUT;
+
       LOCK (reqlock);
 
       for (;;)
@@ -1019,7 +1008,27 @@
           if (req)
             break;
 
-          pthread_cond_wait (&reqwait, &reqlock);
+          ++idle;
+
+          if (pthread_cond_timedwait (&reqwait, &reqlock, &ts)
+              == ETIMEDOUT)
+            {
+              if (idle > max_idle)
+                {
+                  --idle;
+                  UNLOCK (reqlock);
+                  LOCK (wrklock);
+                  --started;
+                  UNLOCK (wrklock);
+                  goto quit;
+                }
+
+              /* we are allowed to idle, so do so without any timeout */
+              pthread_cond_wait (&reqwait, &reqlock);
+              ts.tv_sec  = time (0) + IDLE_TIMEOUT;
+            }
+
+          --idle;
         }
 
       --nready;
@@ -1069,11 +1078,7 @@
               break;
 
             case REQ_QUIT:
-              LOCK (wrklock);
-              worker_free (self);
-              --started;
-              UNLOCK (wrklock);
-              return 0;
+              goto quit;
 
             default:
               req->result = ENOSYS;
@@ -1095,6 +1100,13 @@
 
       UNLOCK (reslock);
     }
+
+quit:
+  LOCK (wrklock);
+  worker_free (self);
+  UNLOCK (wrklock);
+
+  return 0;
 }
 
 /*****************************************************************************/
@@ -1146,8 +1158,11 @@
       worker_free (wrk);
     }
 
-  started = 0;
-  nreqs = 0;
+  started  = 0;
+  idle     = 0;
+  nreqs    = 0;
+  nready   = 0;
+  npending = 0;
 
   close (respipe [0]);
   close (respipe [1]);
@@ -1194,8 +1209,6 @@
 
 	create_pipe ();
         pthread_atfork (atfork_prepare, atfork_parent, atfork_child);
-
-        start_thread ();
 }
 
 void