Try to rationalise the mutex lock/unlock sequence. Hunting for an
[citadel.git] / citadel / sysdep.c
index 7b435ebaa6f4c932611fc5eb08333d11242fbd7a..2428152cef787f378efc9ccaf682d8f52ba77d13 100644 (file)
@@ -180,7 +180,6 @@ volatile int running_as_daemon = 0;
 
 static RETSIGTYPE signal_cleanup(int signum) {
        CtdlLogPrintf(CTDL_DEBUG, "Caught signal %d; shutting down.\n", signum);
-       CtdlThreadStopAll();
        exit_signal = signum;
 }
 
@@ -259,8 +258,30 @@ void init_sysdep(void) {
         * whole Citadel service would come down whenever a single client
         * socket breaks.
         */
-       //signal(SIGPIPE, SIG_IGN);
-       signal(SIGPIPE, signal_cleanup);
+       signal(SIGPIPE, SIG_IGN);
+}
+
+
+
+/*
+ * Obtain a semaphore lock to begin a critical section.
+ * but only if no one else has one
+ */
+int try_critical_section(int which_one)
+{
+       /* For all types of critical sections except those listed here,
+        * ensure nobody ever tries to do a critical section within a
+        * transaction; this could lead to deadlock.
+        */
+       if (    (which_one != S_FLOORCACHE)
+#ifdef DEBUG_MEMORY_LEAKS
+               && (which_one != S_DEBUGMEMLEAKS)
+#endif
+               && (which_one != S_RPLIST)
+       ) {
+               cdb_check_handles();
+       }
+       return (pthread_mutex_trylock(&Critters[which_one]));
 }
 
 
@@ -999,8 +1020,8 @@ static pthread_cond_t thread_gc_cond = PTHREAD_COND_INITIALIZER;
 */
 static pthread_t GC_thread;
 static char *CtdlThreadStates[CTDL_THREAD_LAST_STATE];
-double CtdlThreadLoadAvg;
-
+double CtdlThreadLoadAvg = 0;
+double CtdlThreadWorkerAvg = 0;
 /*
  * Pinched the following bits regarding signals from Kannel.org
  */
@@ -1093,6 +1114,11 @@ void ctdl_thread_internal_init(void)
        // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
        memset (this_thread, 0, sizeof(struct CtdlThreadNode));
        
+       pthread_mutex_init (&(this_thread->ThreadMutex), NULL);
+       pthread_cond_init (&(this_thread->ThreadCond), NULL);
+       pthread_mutex_init (&(this_thread->SleepMutex), NULL);
+       pthread_cond_init (&(this_thread->SleepCond), NULL);
+       
        /* We are garbage collector so create us as running */
        this_thread->state = CTDL_THREAD_RUNNING;
        
@@ -1104,9 +1130,6 @@ void ctdl_thread_internal_init(void)
 
        this_thread->name = strdup("Garbage Collection Thread");
        
-       pthread_mutex_init (&(this_thread->ThreadMutex), NULL);
-       pthread_cond_init (&(this_thread->ThreadCond), NULL);
-       
        this_thread->tid = GC_thread;
        
        num_threads++;  // Increase the count of threads in the system.
@@ -1129,9 +1152,9 @@ void ctdl_thread_internal_init(void)
        struct timeval now, result;
        double last_duration;
 
-       pthread_mutex_lock(&this_thread->ThreadMutex); /* To prevent race condition of a sleeping thread */
        gettimeofday(&now, NULL);
        timersub(&now, &(this_thread->last_state_change), &result);
+       pthread_mutex_lock(&this_thread->ThreadMutex);
        // result now has a timeval for the time we spent in the last state since we last updated
        last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
        if (this_thread->state == CTDL_THREAD_SLEEPING)
@@ -1169,6 +1192,9 @@ void ctdl_thread_internal_change_state (struct CtdlThreadNode *this_thread, enum
  */
 void CtdlThreadStopAll(void)
 {
+       //FIXME: The signalling of the condition should not be in the critical_section
+       // We need to build a list of threads we are going to signal and then signal them afterwards
+       
        struct CtdlThreadNode *this_thread;
        
        begin_critical_section(S_THREAD_LIST);
@@ -1178,7 +1204,10 @@ void CtdlThreadStopAll(void)
                if (this_thread->thread_func) // Don't tell garbage collector to stop
                {
                        ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
+//                     pthread_mutex_lock(&this_thread->ThreadMutex);
                        pthread_cond_signal(&this_thread->ThreadCond);
+                       pthread_cond_signal(&this_thread->SleepCond);
+//                     pthread_mutex_unlock(&this_thread->ThreadMutex);
                        CtdlLogPrintf(CTDL_DEBUG, "Thread system stopping thread \"%s\" (%ld).\n", this_thread->name, this_thread->tid);
                }
                this_thread = this_thread->next;
@@ -1188,21 +1217,25 @@ void CtdlThreadStopAll(void)
 
 
 /*
- * A function to signal that we need to do garbage collection on the thread list
+ * A function to wake up all sleeping threads
  */
-void CtdlThreadGC(void)
+void CtdlThreadWakeAll(void)
 {
        struct CtdlThreadNode *this_thread;
        
-       CtdlLogPrintf(CTDL_DEBUG, "Thread system signalling garbage collection.\n");
+       CtdlLogPrintf(CTDL_DEBUG, "Thread system waking all threads.\n");
        
        begin_critical_section(S_THREAD_LIST);
        this_thread = CtdlThreadList;
        while(this_thread)
        {
                if (!this_thread->thread_func)
+               {
+//                     pthread_mutex_lock(&this_thread->ThreadMutex);
                        pthread_cond_signal(&this_thread->ThreadCond);
-                       
+                       pthread_cond_signal(&this_thread->SleepCond);
+//                     pthread_mutex_unlock(&this_thread->ThreadMutex);
+               }
                this_thread = this_thread->next;
        }
        end_critical_section(S_THREAD_LIST);
@@ -1214,7 +1247,42 @@ void CtdlThreadGC(void)
  */
 int CtdlThreadGetCount(void)
 {
-       return num_threads;
+       int ret;
+       
+       begin_critical_section(S_THREAD_LIST);
+       ret = num_threads;
+       end_critical_section(S_THREAD_LIST);
+       return ret;
+}
+
+int CtdlThreadGetWorkers(void)
+{
+       int ret;
+       
+       begin_critical_section(S_THREAD_LIST);
+       ret =  num_workers;
+       end_critical_section(S_THREAD_LIST);
+       return ret;
+}
+
+double CtdlThreadGetWorkerAvg(void)
+{
+       double ret;
+       
+       begin_critical_section(S_THREAD_LIST);
+       ret =  CtdlThreadWorkerAvg;
+       end_critical_section(S_THREAD_LIST);
+       return ret;
+}
+
+double CtdlThreadGetLoadAvg(void)
+{
+       double ret;
+       
+       begin_critical_section(S_THREAD_LIST);
+       ret =  CtdlThreadLoadAvg;
+       end_critical_section(S_THREAD_LIST);
+       return ret;
 }
 
 /*
@@ -1231,11 +1299,14 @@ struct CtdlThreadNode *CtdlThreadSelf(void)
        this_thread = CtdlThreadList;
        while(this_thread)
        {
+               pthread_mutex_lock(&this_thread->ThreadMutex);
                if (pthread_equal(self_tid, this_thread->tid))
                {
+                       pthread_mutex_unlock(&this_thread->ThreadMutex);
                        end_critical_section(S_THREAD_LIST);
                        return this_thread;
                }
+               pthread_mutex_unlock(&this_thread->ThreadMutex);
                this_thread = this_thread->next;
        }
        end_critical_section(S_THREAD_LIST);
@@ -1260,18 +1331,18 @@ char *CtdlThreadName(struct CtdlThreadNode *thread, char *name)
                this_thread = thread;
        if (!this_thread)
        {
-               CtdlLogPrintf(CTDL_WARNING, "Thread system WARNING. Attempt to CtdlThreadRename() a non thread.\n");
+               CtdlLogPrintf(CTDL_WARNING, "Thread system WARNING. Attempt to CtdlThreadRename() a non thread. %s\n", name);
                return NULL;
        }
-       begin_critical_section(S_THREAD_LIST);
+//     begin_critical_section(S_THREAD_LIST);
+       pthread_mutex_lock(&this_thread->ThreadMutex);
+       old_name = this_thread->name;
        if (name)
-       {
-               old_name = this_thread->name;
                this_thread->name = strdup (name);
-               free(old_name);
-       }
-       old_name = strdup(this_thread->name);
-       end_critical_section (S_THREAD_LIST);
+       else
+               old_name = strdup(old_name);
+       pthread_mutex_unlock(&this_thread->ThreadMutex);
+//     end_critical_section (S_THREAD_LIST);
        return (old_name);
 }      
 
@@ -1301,10 +1372,10 @@ void CtdlThreadCancel(struct CtdlThreadNode *thread)
                return;
        }
        
-       begin_critical_section(S_THREAD_LIST);
+//     begin_critical_section(S_THREAD_LIST);
        ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_CANCELLED);
        pthread_cancel(this_thread->tid);
-       end_critical_section (S_THREAD_LIST);
+//     end_critical_section (S_THREAD_LIST);
 }
 
 
@@ -1312,25 +1383,27 @@ void CtdlThreadCancel(struct CtdlThreadNode *thread)
 /*
  * A function for a thread to check if it has been asked to stop
  */
-int CtdlThreadCheckStop(void)
+int CtdlThreadCheckStop(struct CtdlThreadNode *this_thread)
 {
-       struct CtdlThreadNode *this_thread;
-       
-       this_thread = CtdlThreadSelf();
        if (!this_thread)
        {
                CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, CtdlThreadCheckStop() called by a non thread.\n");
                CtdlThreadStopAll();
                return -1;
        }
+       pthread_mutex_lock(&this_thread->ThreadMutex);
        if(this_thread->state == CTDL_THREAD_STOP_REQ)
        {
                this_thread->state = CTDL_THREAD_STOPPING;
+               pthread_mutex_unlock(&this_thread->ThreadMutex);
                return -1;
        }
-       else if(this_thread->state < CTDL_THREAD_STOP_REQ)
+       else if((this_thread->state < CTDL_THREAD_STOP_REQ) && (this_thread->state > CTDL_THREAD_CREATE))
+       {
+               pthread_mutex_unlock(&this_thread->ThreadMutex);
                return -1;
-               
+       }
+       pthread_mutex_unlock(&this_thread->ThreadMutex);
        return 0;
 }
 
@@ -1352,10 +1425,13 @@ void CtdlThreadStop(struct CtdlThreadNode *thread)
        if (!(this_thread->thread_func))
                return;         // Don't stop garbage collector
                
-       begin_critical_section (S_THREAD_LIST);
+//     begin_critical_section (S_THREAD_LIST);
        ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
+//     pthread_mutex_lock(&this_thread->ThreadMutex);
        pthread_cond_signal(&this_thread->ThreadCond);
-       end_critical_section(S_THREAD_LIST);
+       pthread_cond_signal(&this_thread->SleepCond);
+//     pthread_mutex_unlock(&this_thread->ThreadMutex);
+//     end_critical_section(S_THREAD_LIST);
 }
 
 /*
@@ -1375,20 +1451,24 @@ void CtdlThreadSleep(int secs)
                return;
        }
        
-       begin_critical_section(S_THREAD_LIST);
-       ctdl_thread_internal_change_state (self, CTDL_THREAD_SLEEPING);
-       pthread_mutex_lock(&self->ThreadMutex); /* Prevent something asking us to awaken before we've gone to sleep */
-       end_critical_section(S_THREAD_LIST);
-       
        memset (&wake_time, 0, sizeof(struct timespec));
        gettimeofday(&time_now, NULL);
        wake_time.tv_sec = time_now.tv_sec + secs;
        wake_time.tv_nsec = time_now.tv_usec * 10;
-       pthread_cond_timedwait(&self->ThreadCond, &self->ThreadMutex, &wake_time);
-       begin_critical_section(S_THREAD_LIST);
+
+//     begin_critical_section(S_THREAD_LIST);
+       ctdl_thread_internal_change_state (self, CTDL_THREAD_SLEEPING);
+//     end_critical_section(S_THREAD_LIST);
+       
+//     pthread_mutex_lock(&self->SleepMutex); /* Prevent something asking us to awaken before we've gone to sleep */
+       pthread_mutex_lock(&self->ThreadMutex); /* Prevent something asking us to awaken before we've gone to sleep */
+       pthread_cond_timedwait(&self->SleepCond, &self->ThreadMutex, &wake_time);
        pthread_mutex_unlock(&self->ThreadMutex);
+//     pthread_mutex_unlock(&self->SleepMutex);
+       
+//     begin_critical_section(S_THREAD_LIST);
        ctdl_thread_internal_change_state (self, CTDL_THREAD_RUNNING);
-       end_critical_section(S_THREAD_LIST);
+//     end_critical_section(S_THREAD_LIST);
 }
 
 
@@ -1404,88 +1484,124 @@ static void ctdl_internal_thread_cleanup(void *arg)
         * NB. WE ARE THE CURRENT THREAD
         */
        CtdlLogPrintf(CTDL_NOTICE, "Thread \"%s\" (%ld) exited.\n", this_thread->name, this_thread->tid);
-       begin_critical_section(S_THREAD_LIST);
+//     begin_critical_section(S_THREAD_LIST);
        #ifdef HAVE_BACKTRACE
        eCrash_UnregisterThread();
        #endif
+       pthread_mutex_lock(&this_thread->ThreadMutex);
        this_thread->state = CTDL_THREAD_EXITED;        // needs to be last thing else house keeping will unlink us too early
-       end_critical_section(S_THREAD_LIST);
-       CtdlThreadGC();
+       pthread_mutex_unlock(&this_thread->ThreadMutex);
+//     end_critical_section(S_THREAD_LIST);
+//     CtdlThreadGC();
 }
 
+/*
+ * A quick function to show the load averages
+ */
+void ctdl_thread_internal_calc_loadavg(void)
+{
+       struct CtdlThreadNode *that_thread;
+       double load_avg, worker_avg;
+       int workers = 0;
 
+       that_thread = CtdlThreadList;
+       load_avg = 0;
+       worker_avg = 0;
+       while(that_thread)
+       {
+               /* Update load averages */
+               ctdl_thread_internal_update_avgs(that_thread);
+               pthread_mutex_lock(&that_thread->ThreadMutex);
+               that_thread->load_avg = that_thread->avg_sleeping + that_thread->avg_running + that_thread->avg_blocked;
+               that_thread->load_avg = that_thread->avg_running / that_thread->load_avg * 100;
+               that_thread->avg_sleeping /= 2;
+               that_thread->avg_running /= 2;
+               that_thread->avg_blocked /= 2;
+               load_avg += that_thread->load_avg;
+               if (that_thread->flags & CTDLTHREAD_WORKER)
+               {
+                       worker_avg += that_thread->load_avg;
+                       workers++;
+               }
+#ifdef WITH_THREADLOG
+               CtdlLogPrintf(CTDL_DEBUG, "CtdlThread, \"%s\" (%ld) \"%s\" %f %f %f %f.\n",
+                       that_thread->name,
+                       that_thread->tid,
+                       CtdlThreadStates[that_thread->state],
+                       that_thread->avg_sleeping,
+                       that_thread->avg_running,
+                       that_thread->avg_blocked,
+                       that_thread->load_avg);
+#endif
+               pthread_mutex_unlock(&that_thread->ThreadMutex);
+               that_thread = that_thread->next;
+       }
+       CtdlThreadLoadAvg = load_avg/num_threads;
+       CtdlThreadWorkerAvg = worker_avg/workers;
+#ifdef WITH_THREADLOG
+       CtdlLogPrintf(CTDL_INFO, "System load average %f, workers averag %f, threads %d, workers %d, sessions %d\n", CtdlThreadLoadAvg, CtdlThreadWorkerAvg, num_threads, num_workers, num_sessions);
+#endif
+}
 
 
 /*
  * Garbage collection routine.
  * Gets called by main() in a loop to clean up the thread list periodically.
  */
-void ctdl_internal_thread_gc (void)
+void CtdlThreadGC (void)
 {
-       struct CtdlThreadNode *this_thread, *that_thread = NULL;
-       double load_avg;
+       struct CtdlThreadNode *this_thread, *that_thread;
        int workers = 0;
        
-       /* 
-        * Wait on the condition variable that tells us garbage collection is needed
-        * We wake up every 10 seconds just in case someone forgot to inform us of a thread exiting
-        */
-       
-       CtdlThreadSleep(10);
+       begin_critical_section(S_THREAD_LIST);
        
        /* Handle exiting of garbage collector thread */
        if(num_threads == 1)
                CtdlThreadList->state = CTDL_THREAD_EXITED;
        
+#ifdef WITH_THREADLOG
        CtdlLogPrintf(CTDL_DEBUG, "Thread system running garbage collection.\n");
+#endif
        /*
         * Woke up to do garbage collection
         */
-       begin_critical_section(S_THREAD_LIST);
        this_thread = CtdlThreadList;
-       load_avg = 0;
        while(this_thread)
        {
                that_thread = this_thread;
                this_thread = this_thread->next;
                
-               /* Update load averages */
-               ctdl_thread_internal_update_avgs(that_thread);
-               pthread_mutex_lock(&that_thread->ThreadMutex);
-               that_thread->load_avg = that_thread->avg_sleeping + that_thread->avg_running + that_thread->avg_blocked;
-               that_thread->load_avg = that_thread->avg_running / that_thread->load_avg / 100;
-               that_thread->avg_sleeping /= 10;
-               that_thread->avg_running /= 10;
-               that_thread->avg_blocked /= 10;
-               load_avg += that_thread->load_avg;
-               
-               CtdlLogPrintf(CTDL_DEBUG, "CtdlThread, \"%s\" (%ld) \"%s\" %f %f %f %f.\n", that_thread->name, that_thread->tid, CtdlThreadStates[that_thread->state], that_thread->avg_sleeping, that_thread->avg_running, that_thread->avg_blocked, that_thread->load_avg);
-               pthread_mutex_unlock(&that_thread->ThreadMutex);
-
                /* Do we need to clean up this thread? */
+               pthread_mutex_lock(&that_thread->ThreadMutex);
                if (that_thread->state != CTDL_THREAD_EXITED)
                {
                        if(that_thread->flags & CTDLTHREAD_WORKER)
                                workers++;      /* Sanity check on number of worker threads */
+                       pthread_mutex_unlock(&that_thread->ThreadMutex);
                        continue;
                }
                
                if (pthread_equal(that_thread->tid, pthread_self()) && that_thread->thread_func)
                {       /* Sanity check */
+                       pthread_mutex_unlock(&that_thread->ThreadMutex);
                        end_critical_section(S_THREAD_LIST);
                        CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, a thread is trying to clean up after itself.\n");
-                       CtdlThreadStopAll();
+                       abort();
                        return;
                }
                
                if (num_threads <= 0)
                {       /* Sanity check */
-                       end_critical_section (S_THREAD_LIST);
+                       pthread_mutex_unlock(&that_thread->ThreadMutex);
+                       end_critical_section(S_THREAD_LIST);
                        CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, num_threads <= 0 and trying to do Garbage Collection.\n");
-                       CtdlThreadStopAll();
+                       abort();
                        return;
                }
 
+               if(that_thread->flags & CTDLTHREAD_WORKER)
+                       num_workers--;  /* This is a wroker thread so reduce the count. */
+               num_threads--;
                /* If we are unlinking the list head then the next becomes the list head */
                if (that_thread == CtdlThreadList)
                        CtdlThreadList = that_thread->next;
@@ -1493,10 +1609,12 @@ void ctdl_internal_thread_gc (void)
                        that_thread->prev->next = that_thread->next;
                if(that_thread->next)
                        that_thread->next->prev = that_thread->next;
-               num_threads--;
-               if(that_thread->flags & CTDLTHREAD_WORKER)
-                       num_workers--;  /* This is a wroker thread so reduce the count. */
                
+               pthread_mutex_unlock(&that_thread->ThreadMutex);
+               pthread_cond_signal(&that_thread->ThreadCond);
+               pthread_cond_signal(&that_thread->SleepCond);   // Make sure this thread is awake
+               pthread_mutex_lock(&that_thread->ThreadMutex);  // Make sure it has done what its doing
+               pthread_mutex_unlock(&that_thread->ThreadMutex);
                /*
                 * Join on the thread to do clean up and prevent memory leaks
                 * Also makes sure the thread has cleaned up after itself before we remove it from the list
@@ -1513,6 +1631,8 @@ void ctdl_internal_thread_gc (void)
                        free(that_thread->name);
                pthread_mutex_destroy(&that_thread->ThreadMutex);
                pthread_cond_destroy(&that_thread->ThreadCond);
+               pthread_mutex_destroy(&that_thread->SleepMutex);
+               pthread_cond_destroy(&that_thread->SleepCond);
                pthread_attr_destroy(&that_thread->attr);
                free(that_thread);
        }
@@ -1521,12 +1641,13 @@ void ctdl_internal_thread_gc (void)
        if (workers != num_workers)
        {
                end_critical_section(S_THREAD_LIST);
-               CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, discrepancy in number of worker threads. Counted %d, should be %d.\n", workers, num_workers);
-               return;
+               CtdlLogPrintf(CTDL_EMERG,
+                       "Thread system PANIC, discrepancy in number of worker threads. Counted %d, should be %d.\n",
+                       workers, num_workers
+                       );
+               abort();
        }
-       CtdlThreadLoadAvg = load_avg/num_threads;
        end_critical_section(S_THREAD_LIST);
-       CtdlLogPrintf(CTDL_INFO, "System load average %f.\n", CtdlThreadLoadAvg);
 }
 
 
@@ -1547,25 +1668,44 @@ static void *ctdl_internal_thread_func (void *arg)
         * can continue its execution.
         */
        begin_critical_section(S_THREAD_LIST);
-       // Get our thread data structure
        this_thread = (struct CtdlThreadNode *) arg;
-       this_thread->state = CTDL_THREAD_RUNNING;
-       this_thread->pid = getpid();
        gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
+       pthread_mutex_lock(&this_thread->ThreadMutex);
+       
+       // Register the cleanup function to take care of when we exit.
+       pthread_cleanup_push(ctdl_internal_thread_cleanup, NULL);
+       // Get our thread data structure
+       this_thread->pid = getpid();
        memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
-       end_critical_section(S_THREAD_LIST);
+       /* Only change to running state if we weren't asked to stop during the create cycle
+        * Other wise there is a window to allow this threads creation to continue to full grown and
+        * therby prevent a shutdown of the server.
+        */
+       pthread_mutex_unlock(&this_thread->ThreadMutex);
                
+       if (!CtdlThreadCheckStop(this_thread))
+       {
+               pthread_mutex_lock(&this_thread->ThreadMutex);
+               this_thread->state = CTDL_THREAD_RUNNING;
+               pthread_mutex_unlock(&this_thread->ThreadMutex);
+       }
+       end_critical_section(S_THREAD_LIST);
+       
+       // Register for tracing
+       #ifdef HAVE_BACKTRACE
+       eCrash_RegisterThread(this_thread->name, 0);
+       #endif
+       
        // Tell the world we are here
        CtdlLogPrintf(CTDL_NOTICE, "Created a new thread \"%s\" (%ld). \n", this_thread->name, this_thread->tid);
 
-       // Register the cleanup function to take care of when we exit.
-       pthread_cleanup_push(ctdl_internal_thread_cleanup, NULL);
        
        
        /*
-        * run the thread to do the work
+        * run the thread to do the work but only if we haven't been asked to stop
         */
-       ret = (this_thread->thread_func)(this_thread->user_args);
+       if (!CtdlThreadCheckStop(this_thread))
+               ret = (this_thread->thread_func)(this_thread->user_args);
        
        /*
         * Our thread is exiting either because it wanted to end or because the server is stopping
@@ -1603,9 +1743,22 @@ struct CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void
        // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
        memset (this_thread, 0, sizeof(struct CtdlThreadNode));
        
+       /* Create the mutex's early so we can use them */
+       pthread_mutex_init (&(this_thread->ThreadMutex), NULL);
+       pthread_cond_init (&(this_thread->ThreadCond), NULL);
+       pthread_mutex_init (&(this_thread->SleepMutex), NULL);
+       pthread_cond_init (&(this_thread->SleepCond), NULL);
+       
+       pthread_mutex_lock(&this_thread->ThreadMutex);
+       
        this_thread->state = CTDL_THREAD_CREATE;
        
        if ((ret = pthread_attr_init(&this_thread->attr))) {
+               pthread_mutex_unlock(&this_thread->ThreadMutex);
+               pthread_mutex_destroy(&(this_thread->ThreadMutex));
+               pthread_cond_destroy(&(this_thread->ThreadCond));
+               pthread_mutex_destroy(&(this_thread->SleepMutex));
+               pthread_cond_destroy(&(this_thread->SleepCond));
                CtdlLogPrintf(CTDL_EMERG, "Thread system, pthread_attr_init: %s\n", strerror(ret));
                free(this_thread);
                return NULL;
@@ -1619,9 +1772,14 @@ struct CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void
        {
                CtdlLogPrintf(CTDL_INFO, "Thread system. Creating BIG STACK thread.\n");
                if ((ret = pthread_attr_setstacksize(&this_thread->attr, THREADSTACKSIZE))) {
+                       pthread_mutex_unlock(&this_thread->ThreadMutex);
+                       pthread_mutex_destroy(&(this_thread->ThreadMutex));
+                       pthread_cond_destroy(&(this_thread->ThreadCond));
+                       pthread_mutex_destroy(&(this_thread->SleepMutex));
+                       pthread_cond_destroy(&(this_thread->SleepCond));
+                       pthread_attr_destroy(&this_thread->attr);
                        CtdlLogPrintf(CTDL_EMERG, "Thread system, pthread_attr_setstacksize: %s\n",
                                strerror(ret));
-                       pthread_attr_destroy(&this_thread->attr);
                        free(this_thread);
                        return NULL;
                }
@@ -1644,8 +1802,11 @@ struct CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void
        this_thread->flags = flags;
        this_thread->thread_func = thread_func;
        this_thread->user_args = args;
-       pthread_mutex_init (&(this_thread->ThreadMutex), NULL);
-       pthread_cond_init (&(this_thread->ThreadCond), NULL);
+       /* Set this new thread with an avg_blocked of 2. We do this so that its creation affects the
+        * load average for the system. If we don't do this then we create a mass of threads at the same time 
+        * because the creation didn't affect the load average.
+        */
+       this_thread->avg_blocked = 2;
        
        /*
         * We want to make sure that only the main thread handles signals,
@@ -1675,6 +1836,8 @@ struct CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void
                        free (this_thread->name);
                pthread_mutex_destroy(&(this_thread->ThreadMutex));
                pthread_cond_destroy(&(this_thread->ThreadCond));
+               pthread_mutex_destroy(&(this_thread->SleepMutex));
+               pthread_cond_destroy(&(this_thread->SleepCond));
                pthread_attr_destroy(&this_thread->attr);
                free(this_thread);
                if (sigtrick)
@@ -1693,10 +1856,10 @@ struct CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void
        CtdlThreadList = this_thread;
        if (this_thread->next)
                this_thread->next->prev = this_thread;
-       // Register for tracing
-       #ifdef HAVE_BACKTRACE
-       eCrash_RegisterThread(this_thread->name, 0);
-       #endif
+       
+       pthread_mutex_unlock(&this_thread->ThreadMutex);
+       
+       ctdl_thread_internal_calc_loadavg();
        return this_thread;
 }
 
@@ -1721,12 +1884,10 @@ struct CtdlThreadNode *CtdlThreadCreate(char *name, long flags, void *(*thread_f
 /*
  * A warapper function for select so we can show a thread as blocked
  */
-int CtdlThreadSelect(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, const struct timeval *timeout)
+int CtdlThreadSelect(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, const struct timeval *timeout, struct CtdlThreadNode *self)
 {
-       struct CtdlThreadNode *self;
        int ret;
        
-       self = CtdlThreadSelf();
        ctdl_thread_internal_change_state(self, CTDL_THREAD_BLOCKED);
        ret = select(n, readfds, writefds, exceptfds, timeout);
        ctdl_thread_internal_change_state(self, CTDL_THREAD_RUNNING);
@@ -1739,15 +1900,11 @@ int CtdlThreadSelect(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds
  * few seconds, because running it after every single unbind would waste a lot
  * of CPU time and keep the context list locked too much.  To force it to run
  * anyway, set "force" to nonzero.
- *
- *
- * After that's done, we raise the size of the worker thread pool
- * if such an action is appropriate.
  */
 void dead_session_purge(int force) {
        struct CitContext *ptr, *ptr2;          /* general-purpose utility pointer */
        struct CitContext *rem = NULL;  /* list of sessions to be destroyed */
-
+       
        if (force == 0) {
                if ( (time(NULL) - last_purge) < 5 ) {
                        return; /* Too soon, go away */
@@ -1755,7 +1912,9 @@ void dead_session_purge(int force) {
        }
        time(&last_purge);
 
-       begin_critical_section(S_SESSION_TABLE);
+       if (try_critical_section(S_SESSION_TABLE))
+               return;
+               
        ptr = ContextList;
        while (ptr) {
                ptr2 = ptr;
@@ -1774,11 +1933,9 @@ void dead_session_purge(int force) {
                        }
 
                        --num_sessions;
-
                        /* And put it on our to-be-destroyed list */
                        ptr2->next = rem;
                        rem = ptr2;
-
                }
        }
        end_critical_section(S_SESSION_TABLE);
@@ -1794,15 +1951,6 @@ void dead_session_purge(int force) {
                rem = rem->next;
                free(ptr);
        }
-
-       /* Raise the size of the worker thread pool if necessary. */
-       begin_critical_section(S_THREAD_LIST);
-       if ( (num_sessions > num_workers)
-          && (num_workers < config.c_max_workers) ) {
-               ctdl_internal_create_thread(NULL, CTDLTHREAD_BIGSTACK + CTDLTHREAD_WORKER, worker_thread, NULL);
-       }
-       end_critical_section(S_THREAD_LIST);
-       // FIXME: reduce the number of worker threads too
 }
 
 
@@ -1849,10 +1997,12 @@ void *worker_thread(void *arg) {
        struct timeval tv;
        int force_purge = 0;
        int m;
-
+       
+       CT_PUSH();
+       
        cdb_allocate_tsd();
 
-       while (!CtdlThreadCheckStop()) {
+       while (!CtdlThreadCheckStop(CT)) {
 
                /* make doubly sure we're not holding any stale db handles
                 * which might cause a deadlock.
@@ -1898,14 +2048,13 @@ do_select:      force_purge = 0;
                        }
                }
 
-               if (!CtdlThreadCheckStop()) {
+               if (!CtdlThreadCheckStop(CT)) {
                        tv.tv_sec = 1;          /* wake up every second if no input */
                        tv.tv_usec = 0;
-                       retval = CtdlThreadSelect(highest + 1, &readfds, NULL, NULL, &tv);
-//                     retval = select(highest + 1, &readfds, NULL, NULL, &tv);
+                       retval = CtdlThreadSelect(highest + 1, &readfds, NULL, NULL, &tv, CT);
                }
 
-               if (CtdlThreadCheckStop()) return(NULL);
+               if (CtdlThreadCheckStop(CT)) return(NULL);
 
                /* Now figure out who made this select() unblock.
                 * First, check for an error or exit condition.
@@ -1919,14 +2068,14 @@ do_select:      force_purge = 0;
                        if (errno != EINTR) {
                                CtdlLogPrintf(CTDL_EMERG, "Exiting (%s)\n", strerror(errno));
                                CtdlThreadStopAll();
-                       } else if (!CtdlThreadCheckStop()) {
+                       } else if (!CtdlThreadCheckStop(CT)) {
                                CtdlLogPrintf(CTDL_DEBUG, "Un handled select failure.\n");
                                goto do_select;
                        }
                }
-               else if(retval == 0) {
-                       goto SKIP_SELECT;
-               }
+//             else if(retval == 0) {
+//                     goto SKIP_SELECT;
+//             }
                /* Next, check to see if it's a new client connecting
                 * on a master socket.
                 */
@@ -2032,7 +2181,6 @@ SKIP_SELECT:
 
                dead_session_purge(force_purge);
                do_housekeeping();
-               check_sched_shutdown();
        }
        /* If control reaches this point, the server is shutting down */        
        return(NULL);