RuntimeError: received 0 items of
ancdata错误是在dataloader加载数据时出现的错误,原因是pytorch多线程共享tensor是通过打开文件的方式实现的,而打开文件的数量是有限制的,通过
ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 128088
max locked memory (kbytes, -l) 16384
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 128088
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
可查看,当需共享的tensor超过open files限制时,即会出现该错误。
解决办法有2种:
- 1、增加open files的限制数量:
不能用sudo ulimit -n命令,而需执行:
sudo sh -c "ulimit -n 65535 && exec su $LOGNAME"
- 2、修改多线程的tensor方式为file_system(默认方式为file_descriptor,受限于open files数量):
torch.multiprocessing.set_sharing_strategy('file_system')