ckdb - allow adjusting the reload process thread count

src/ckdb.c

@@ -117,14 +117,17 @@ static bool blistener_using_data;
 static bool breakdown_using_data;
 static bool replier_using_data;
 
-// Define the array size for thread data
-#define THREAD_LIMIT 99
+/* Flag to notify thread changes
+ * Set/checked under the function's main loop's first lock
+ * This is always a 'delta' value meaning add or subtract that many */
+int queue_threads_delta = 0;
 /* Use -Q to set it higher
- * Setting it higher can degrade performance if the server can't
- *  handle the extra locking or is swapping */
+ * Setting it higher can degrade performance if the CPUs can't
+ *  handle the extra locking or the threads are swapping */
 static int queue_threads = 1;
 // -B to override calculated value
 static int breakdown_threads = -1;
+// cpu count to breakdown thread ratio
 #define BREAKDOWN_RATIO 3
 static int reload_breakdown_count = 0;
 static int cmd_breakdown_count = 0;
@@ -5395,6 +5398,7 @@ static void *process_socket(void *arg)
 				case CMD_SHSTA:
 				case CMD_CHKPASS:
 				case CMD_GETATTS:
+				case CMD_THREADS:
 				case CMD_HOMEPAGE:
 					break;
 				default:
@@ -5586,6 +5590,7 @@ static void *process_socket(void *arg)
 			case CMD_LOCKS:
 			case CMD_EVENTS:
 			case CMD_HIGH:
+			case CMD_THREADS:
 				msgline->sockd = bq->sockd;
 				bq->sockd = -1;
 				K_WLOCK(workqueue_free);
@@ -6020,6 +6025,7 @@ static void process_reload_item(PGconn *conn, K_ITEM *bq_item)
 		case CMD_LOCKS:
 		case CMD_EVENTS:
 		case CMD_HIGH:
+		case CMD_THREADS:
 			LOGERR("%s() INVALID message line %"PRIu64
 				" ignored '%.42s...",
 				__func__, bq->count,
@@ -6077,37 +6083,37 @@ static void process_reload_item(PGconn *conn, K_ITEM *bq_item)
 
 static void *process_reload(__maybe_unused void *arg)
 {
-	pthread_t *procrel_pt;
+	static pthread_t procrel_pt[THREAD_LIMIT];
+	static int n[THREAD_LIMIT];
+	static bool running[THREAD_LIMIT];
+
 	PGconn *conn = NULL;
 	K_ITEM *bq_item = NULL;
 	char buf[128];
 	time_t now;
-	int i, *n, zeros;
 	ts_t when, when_add;
-	int ret;
+	int i, mythread, threads_delta = 0, done, tot, ret;
 
 	if (arg)
-		i = *(int *)(arg);
+		mythread = *(int *)(arg);
 	else {
 		pthread_detach(pthread_self());
 
-		n = malloc(queue_threads * sizeof(int));
-		procrel_pt = malloc(queue_threads * sizeof(*procrel_pt));
-		for (i = 1; i < queue_threads; i++) {
+		for (i = 0; i < THREAD_LIMIT; i++) {
 			n[i] = i;
-			create_pthread(&(procrel_pt[i]), process_reload, &(n[i]));
+			running[i] = false;
 		}
-		i = 0;
+
+		mythread = 0;
+		running[0] = true;
+
+		// Set to create the rest of the threads
+		queue_threads_delta = queue_threads - 1;
 
 		LOGNOTICE("%s() starting", __func__);
 	}
 
-	if (queue_threads < 10)
-		zeros = 1;
-	else
-		zeros = (int)log10(queue_threads) + 1;
-
-	snprintf(buf, sizeof(buf), "db_p%0*drload", zeros, i);
+	snprintf(buf, sizeof(buf), "db_p%02drload", mythread);
 	LOCK_INIT(buf);
 	rename_proc(buf);
 
@@ -6119,13 +6125,70 @@ static void *process_reload(__maybe_unused void *arg)
 
 	while (!everyone_die) {
 		K_WLOCK(breakqueue_free);
-		bq_item = k_unlink_head(reload_done_breakqueue_store);
-		if (bq_item) {
-			reload_processing++;
-			reload_processed++;
+		if (mythread == 0 && queue_threads_delta != 0) {
+			threads_delta = queue_threads_delta;
+			queue_threads_delta = 0;
+		} else {
+			bq_item = k_unlink_head(reload_done_breakqueue_store);
+			if (bq_item) {
+				reload_processing++;
+				reload_processed++;
+			}
 		}
 		K_WUNLOCK(breakqueue_free);
 
+		if (!running[mythread])
+			break;
+
+		// TODO: deal with thread creation/shutdown failure
+		if (threads_delta != 0) {
+			if (threads_delta > 0) {
+				// Add threads
+				tot = 1;
+				done = 0;
+				for (i = 1; i < THREAD_LIMIT; i++) {
+					if (!running[i]) {
+						if (threads_delta > 0) {
+							threads_delta--;
+							running[i] = true;
+							create_pthread(&(procrel_pt[i]),
+									process_reload,
+									&(n[i]));
+							done++;
+							tot++;
+						}
+					} else
+						tot++;
+				}
+				LOGWARNING("%s() created %d thread%s total now"
+					   " %d",
+					   __func__, done,
+					   (done == 1) ? EMPTY : "s", tot);
+			} else {
+				// Notify and wait for each to exit
+				tot = 1;
+				done = 0;
+				i = THREAD_LIMIT - 1;
+				for (i = THREAD_LIMIT - 1; i > 0; i--) {
+					if (running[i]) {
+						if (threads_delta < 0) {
+							threads_delta++;
+							running[i] = false;
+							join_pthread(procrel_pt[i]);
+							done++;
+						} else
+							tot++;
+					}
+				}
+				LOGWARNING("%s() stopped %d thread%s total now"
+					   " %d",
+					   __func__, done,
+					   (done == 1) ? EMPTY : "s", tot);
+			}
+			threads_delta = 0;
+			continue;
+		}
+
 		if (!bq_item) {
 			// Finished reloading?
 			if (!reloading)
@@ -6165,9 +6228,12 @@ static void *process_reload(__maybe_unused void *arg)
 
 	PQfinish(conn);
 
-	if (!arg) {
-		for (i = 1; i < queue_threads; i++)
-			join_pthread(procrel_pt[i]);
+	// Only when everyone_die is true
+	if (mythread == 0) {
+		for (i = 1; i < THREAD_LIMIT; i++) {
+			if (running[i])
+				join_pthread(procrel_pt[i]);
+		}
 
 		LOGNOTICE("%s() exiting, processed %"PRIu64,
 			  __func__, reload_processed);

src/ckdb.h

@@ -11,8 +11,11 @@
 #ifndef CKDB_H
 #define CKDB_H
 
-// Remove this line if you have an old GCC version
+#ifdef __GNUC__
+#if __GNUC__ >= 6
 #pragma GCC diagnostic ignored "-Wtautological-compare"
+#endif
+#endif
 
 #include "config.h"
 
@@ -55,7 +58,7 @@
 
 #define DB_VLOCK "1"
 #define DB_VERSION "1.0.7"
-#define CKDB_VERSION DB_VERSION"-2.400"
+#define CKDB_VERSION DB_VERSION"-2.401"
 
 #define WHERE_FFL " - from %s %s() line %d"
 #define WHERE_FFL_HERE __FILE__, __func__, __LINE__
@@ -115,6 +118,13 @@ enum free_modes {
 
 extern enum free_modes free_mode;
 
+// Define the array size for thread data
+#define THREAD_LIMIT 99
+/* Flag to notify thread changes
+ * Set/checked under the function's main loop's first lock
+ * This is always a 'delta' value meaning add or subtract that many */
+extern int queue_threads_delta;
+
 #define BLANK " "
 extern char *EMPTY;
 extern const char *nullstr;
@@ -722,6 +732,7 @@ enum cmd_values {
 	CMD_LOCKS,
 	CMD_EVENTS,
 	CMD_HIGH,
+	CMD_THREADS,
 	CMD_END
 };
 

src/ckdb_cmd.c

@@ -8356,6 +8356,61 @@ static char *cmd_high(PGconn *conn, char *cmd, char *id,
 	return buf;
 }
 
+// Running thread adjustments
+static char *cmd_threads(__maybe_unused PGconn *conn, char *cmd, char *id,
+			 __maybe_unused tv_t *now, __maybe_unused char *by,
+			 __maybe_unused char *code, __maybe_unused char *inet,
+			 __maybe_unused tv_t *cd, K_TREE *trf_root,
+			 __maybe_unused bool reload_data)
+{
+	K_ITEM *i_name, *i_delta;
+	char *name, *delta;
+	char reply[1024] = "";
+	size_t siz = sizeof(reply);
+	char *buf = NULL;
+	int delta_value = 0;
+
+	LOGDEBUG("%s(): cmd '%s'", __func__, cmd);
+
+	i_name = require_name(trf_root, "name", 1, NULL, reply, siz);
+	if (!i_name)
+		return strdup(reply);
+	name = transfer_data(i_name);
+	i_delta = require_name(trf_root, "delta", 2, NULL, reply, siz);
+	if (!i_delta)
+		return strdup(reply);
+	delta = transfer_data(i_delta);
+	if (*delta != '+' && *delta != '-') {
+		snprintf(reply, siz, "invalid delta '%s'", delta);
+		LOGERR("%s() %s.%s", __func__, id, reply);
+		return strdup(reply);
+	}
+	delta_value = atoi(delta+1);
+	if (delta_value < 1 || delta_value >= THREAD_LIMIT) {
+		snprintf(reply, siz, "invalid delta range '%s'", delta);
+		LOGERR("%s() %s.%s", __func__, id, reply);
+		return strdup(reply);
+	}
+	if (*delta == '-')
+		delta_value = -delta_value;
+
+	if (strcasecmp(name, "pr") == 0 ||
+	    strcasecmp(name, "process_reload") == 0) {
+		K_WLOCK(breakqueue_free);
+		// Just overwrite whatever's there
+		queue_threads_delta = delta_value;
+		K_WUNLOCK(breakqueue_free);
+		snprintf(reply, siz, "ok.delta %d request sent", delta_value);
+		return strdup(reply);
+	} else {
+		snprintf(reply, siz, "unknown name '%s'", name);
+		LOGERR("%s() %s.%s", __func__, id, reply);
+		return strdup(reply);
+	}
+
+	return buf;
+}
+
 /* The socket command format is as follows:
  *  Basic structure:
  *    cmd.ID.fld1=value1 FLDSEP fld2=value2 FLDSEP fld3=...
@@ -8468,5 +8523,6 @@ struct CMDS ckdb_cmds[] = {
 	{ CMD_LOCKS,	"locks",	false,	false,	cmd_locks,	SEQ_NONE,	ACCESS_SYSTEM },
 	{ CMD_EVENTS,	"events",	false,	false,	cmd_events,	SEQ_NONE,	ACCESS_SYSTEM },
 	{ CMD_HIGH,	"high",		false,	false,	cmd_high,	SEQ_NONE,	ACCESS_SYSTEM },
+	{ CMD_THREADS,	"threads",	false,	false,	cmd_threads,	SEQ_NONE,	ACCESS_SYSTEM },
 	{ CMD_END,	NULL,		false,	false,	NULL,		SEQ_NONE,	0 }
 };