From b5a6bc4a481cec8db2afc0bc507e3eea21cc30ed Mon Sep 17 00:00:00 2001
From: Jean-loup Gailly <jloup@gailly.net>
Date: Wed, 13 Jan 2010 01:18:54 +0100
Subject: [PATCH] Define a memory limit for nodes to avoid crashing later.

---
 uct/tree.c | 1 +
 uct/tree.h | 1 +
 uct/walk.c | 7 +++++--
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/uct/tree.c b/uct/tree.c
index 77cf9d4..b431d6b 100644
--- a/uct/tree.c
+++ b/uct/tree.c
@@ -27,6 +27,7 @@ tree_init_node(struct tree *t, coord_t coord, int depth)
 		fprintf(stderr, "tree_init_node(): OUT OF MEMORY\n");
 		exit(1);
 	}
+	__sync_fetch_and_add(&t->node_sizes, sizeof(*n));
 	n->coord = coord;
 	n->depth = depth;
 	volatile static long c = 1000000;
diff --git a/uct/tree.h b/uct/tree.h
index e74fa5f..97cb5f8 100644
--- a/uct/tree.h
+++ b/uct/tree.h
@@ -69,6 +69,7 @@ struct tree {
 
 	// Statistics
 	int max_depth;
+	volatile long node_sizes; // byte size of all allocated nodes
 };
 
 struct tree *tree_init(struct board *board, enum stone color);
diff --git a/uct/walk.c b/uct/walk.c
index f1361b1..4ea2f28 100644
--- a/uct/walk.c
+++ b/uct/walk.c
@@ -19,6 +19,8 @@
 #include "uct/uct.h"
 #include "uct/walk.h"
 
+// This should become a dynamic parameter. 7G is suitable for 20k*23 threads.
+#define MAX_NODE_SIZES (7L*1024*1024*1024)
 
 float
 uct_get_extra_komi(struct uct *u, struct board *b)
@@ -91,7 +93,7 @@ uct_leaf_node(struct uct *u, struct board *b, enum stone player_color,
 {
 	enum stone next_color = stone_other(node_color);
 	int parity = (next_color == player_color ? 1 : -1);
-	if (n->u.playouts >= u->expand_p) {
+	if (n->u.playouts >= u->expand_p && t->node_sizes < MAX_NODE_SIZES) {
 		// fprintf(stderr, "expanding %s (%p ^-%p)\n", coord2sstr(n->coord, b), n, n->parent);
 		if (!u->parallel_tree) {
 			/* Single-threaded, life is easy. */
@@ -102,7 +104,8 @@ uct_leaf_node(struct uct *u, struct board *b, enum stone player_color,
 			 * threads to meet in the same node, the latter
 			 * one will simply do another simulation from
 			 * the node itself, no big deal. */
-			if (!__sync_lock_test_and_set(&n->is_expanded, 1)) {
+			if (!__sync_lock_test_and_set(&n->is_expanded, 1) &&
+			    t->node_sizes < MAX_NODE_SIZES) {
 				assert(tree_leaf_node(n));
 				tree_expand_node(t, n, b, next_color, u, parity);
 			}
-- 
2.11.4.GIT