Though, I checked now.
I can create 1 million files in a directory on my Ubuntu box with the ext4 file system.
So, it should work with the current configuration.
after using the latest master code, the user images are not shown.
the URLs are not correct, for example:
http://www.zaijiajiaoyu.net/uploads/1-profileimg.png%3C!--%20ENDIF%20topics.thumb%20--%3E
but if I remove the tail section, it works.
http://www.zaijiajiaoyu.net/uploads/1-profileimg.png
topics.thumb
[email protected]:~/projects/forum.zaijiajiaoyu.net$ grep -R 'topics.thumb' *
public/templates/category.tpl: <img src="<!-- IF topics.thumb -->{topics.thumb}<!-- ELSE -->{topics.picture}<!-- ENDIF topics.thumb -->" class="img-rounded user-img" title="{topics.username}"/>