Initial implementation of the worker thread pool size manager

diff --git a/citadel/sysdep.c b/citadel/sysdep.c
index a64eca0209899e1279b8dfaa9138f16b3eff7ea8..f9a2f07d6bc0723c1f0a3cbdee42fac1a5ed3416 100644 (file)
--- a/citadel/sysdep.c
+++ b/citadel/sysdep.c
@@ -1139,6 +1139,8 @@ void *worker_thread(void *blah) {
        struct timeval tv;
        int force_purge = 0;
 
+       ++num_workers;
+
        while (!CtdlThreadCheckStop()) {
 
                /* make doubly sure we're not holding any stale db handles
@@ -1250,6 +1252,7 @@ do_select:        force_purge = 0;
 
 SKIP_SELECT:
                /* We're bound to a session */
+               ++active_workers;
                if (bind_me != NULL) {
                        become_session(bind_me);
 
@@ -1283,6 +1286,7 @@ SKIP_SELECT:
 
                dead_session_purge(force_purge);
                do_housekeeping();
+               --active_workers;
        }
        /* If control reaches this point, the server is shutting down */        
        return(NULL);

diff --git a/citadel/threads.c b/citadel/threads.c
index 3d2a1932f3d846ed0da71a75abdfc4b8beba95ce..d60867df87daddfc8d8822073b24a9d92554c9e7 100644 (file)
--- a/citadel/threads.c
+++ b/citadel/threads.c
@@ -61,19 +61,8 @@
 #include "context.h"
 
 
-/*
- * To create a thread you must call one of the create thread functions.
- * You must pass it the address of (a pointer to a CtdlThreadNode initialised to NULL) like this
- * struct CtdlThreadNode *node = NULL;
- * pass in &node
- * If the thread is created *node will point to the thread control structure for the created thread.
- * If the thread creation fails *node remains NULL
- * Do not free the memory pointed to by *node, it doesn't belong to you.
- * This new interface duplicates much of the eCrash stuff. We should go for closer integration since that would
- * remove the need for the calls to eCrashRegisterThread and friends
- */
-
-static int num_threads = 0;                    /* Current number of threads */
+int num_workers = 0;                           /* Current number of worker threads */
+int active_workers = 0;                                /* Number of ACTIVE worker threads */
 pthread_key_t ThreadKey;
 pthread_mutex_t Critters[MAX_SEMAPHORES];      /* Things needing locking */
 struct thread_tsd masterTSD;
@@ -205,8 +194,6 @@ void CtdlThreadCreate(void *(*start_routine)(void*))
        ret = pthread_attr_setstacksize(&attr, THREADSTACKSIZE);
        ret = pthread_create(&thread, &attr, CTC_backend, (void *)start_routine);
        if (ret != 0) syslog(LOG_EMERG, "pthread_create() : %s", strerror(errno));
-
-       ++num_threads;
 }
 
 
@@ -230,20 +217,19 @@ void go_threading(void)
 
        CtdlThreadCreate(select_on_master);
 
-       /* FIXME temporary fixed size pool of worker threads */
-       CtdlThreadCreate(worker_thread);
-       CtdlThreadCreate(worker_thread);
-       CtdlThreadCreate(worker_thread);
+       /* Begin with one worker thread.  We will expand the pool if necessary */
        CtdlThreadCreate(worker_thread);
-       CtdlThreadCreate(worker_thread);
-       CtdlThreadCreate(worker_thread);
-       CtdlThreadCreate(worker_thread);
-       CtdlThreadCreate(worker_thread);
-
-       /* At this point I am a union worker and therefore serve no useful purpose. */
 
+       /* The supervisor thread monitors worker threads and spawns more of them if it finds that
+        * they are all in use.  FIXME make the 256 max threads a configurable value.
+        */
        while(!CtdlThreadCheckStop()) {
-               sleep(3);
+               if ((active_workers == num_workers) && (num_workers < 256)) {
+                       syslog(LOG_DEBUG, "worker threads: %d, active: %d\n", num_workers, active_workers);
+                       CtdlThreadCreate(worker_thread);
+                       syslog(LOG_DEBUG, "worker threads: %d, active: %d\n", num_workers, active_workers);
+               }
+               sleep(1);
        }
 
        /* Shut down */

diff --git a/citadel/threads.h b/citadel/threads.h
index 082ff4da885dfd246a2e1aa5b00f9ea63ebd6c03..b673c6c074a13545188f41bcb9be89e0accf76e2 100644 (file)
--- a/citadel/threads.h
+++ b/citadel/threads.h
@@ -33,6 +33,9 @@ struct thread_tsd {
 extern struct thread_tsd masterTSD;
 #define TSD MyThread()
 
+extern int num_workers;
+extern int active_workers;
+
 struct thread_tsd *MyThread(void);
 int try_critical_section (int which_one);
 void begin_critical_section (int which_one);