RW-splitting partitionning, ERROR 24

[slytay slytay]

I'm actually using the 0.8.0 mysql-proxy.
i've a random error when i use mysqlslap, for stressing Mysql with partitionning by range (date).

MY variables:

key_buffer_size = 1024M
max_allowed_packet = 1M
table_open_cache = 1024
table_definition_cache=1024
sort_buffer_size = 1M
read_buffer_size = 1M
read_rnd_buffer_size = 4M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size= 16M
open_files_limit=32640
max_connections = 500
# Try number of CPU's*2 for thread_concurrency
thread_concurrency = 8

Undepending if master-slave :
ERROR : Out of resources when opening file './DATABASEX/TABLETEST#P#p200101.MYD' (Errcode: 24)