HHVM 3.6 has problem with MariaDB

The same script php file, always works smoothly on HHVM 3.2 to HHVM 3.5. Until I upgrade it to HHVM 3.6.

It is a simply script which use mysqli connection and so on. Now it is shown the error as below:

Connect failed: Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)

I tried to find the answer and faild. So I upgrde the HHVM to nightly build version. It is 3.7-dev.

davidyin@fiob:/etc/hhvm$ hhvm --version
HipHop VM 3.7.0-dev (rel)
Compiler: heads/master-0-g0359d4a4bbb22c5defd7eb024194aed0af24c80b
Repo schema: 9008d5e6e7f6584d09ed3b14deceac5a34f363c1

And it did solve the error, and the script is working as expected.

But, later I found the reason why it happen.

Add

hhvm.mysql.socket = /tmp/mysql.sock

into server.ini

To specify the mysql socket and let HHVM knows how to connect mySQL server or MariaDB server.

I did not try the solution.  I found it here.