rculfhash: handle pthread_create failures

[urcu.git] / rculfhash.c

diff --git a/rculfhash.c b/rculfhash.c
index 7d39388f494700a1b06a5df885d5a5350cdf42a8..8a8ede7a6cadd1027a2c55c450ac3016f696fa6c 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -1171,7 +1171,7 @@ void partition_resize_helper(struct cds_lfht *ht, unsigned long i,
                void (*fct)(struct cds_lfht *ht, unsigned long i,
                        unsigned long start, unsigned long len))
 {
-       unsigned long partition_len;
+       unsigned long partition_len, start = 0;
        struct partition_resize_work *work;
        int thread, ret;
        unsigned long nr_threads;
@@ -1189,7 +1189,10 @@ void partition_resize_helper(struct cds_lfht *ht, unsigned long i,
        }
        partition_len = len >> cds_lfht_get_count_order_ulong(nr_threads);
        work = calloc(nr_threads, sizeof(*work));
-       assert(work);
+       if (!work) {
+               dbg_printf("error allocating for resize, single-threading\n");
+               goto fallback;
+       }
        for (thread = 0; thread < nr_threads; thread++) {
                work[thread].ht = ht;
                work[thread].i = i;
@@ -1198,6 +1201,17 @@ void partition_resize_helper(struct cds_lfht *ht, unsigned long i,
                work[thread].fct = fct;
                ret = pthread_create(&(work[thread].thread_id), ht->resize_attr,
                        partition_resize_thread, &work[thread]);
+               if (ret == EAGAIN) {
+                       /*
+                        * Out of resources: wait and join the threads
+                        * we've created, then handle leftovers.
+                        */
+                       dbg_printf("error spawning for resize, single-threading\n");
+                       start = work[thread].start;
+                       len -= start;
+                       nr_threads = thread;
+                       break;
+               }
                assert(!ret);
        }
        for (thread = 0; thread < nr_threads; thread++) {
@@ -1205,6 +1219,18 @@ void partition_resize_helper(struct cds_lfht *ht, unsigned long i,
                assert(!ret);
        }
        free(work);
+
+       /*
+        * A pthread_create failure above will either lead in us having
+        * no threads to join or starting at a non-zero offset,
+        * fallback to single thread processing of leftovers.
+        */
+       if (start == 0 && nr_threads > 0)
+               return;
+fallback:
+       ht->flavor->thread_online();
+       fct(ht, i, start, len);
+       ht->flavor->thread_offline();
 }
 
 /*