Finally, I find out the problem, but may not the one I said above. It seems a little bug exsited.

In my deployment, it will install some buildpacks by default, but perhaps caused by some network issues, the buildpack not compete. Which make the dea_next start check the SHA is not match. It continue try to download the buildpacks. I have to delete all buildpack in CF, as well as clean the folder /var/vcap/data/dea_next/tmp/* in each DEA, and restart DEA_NEXT.