I  noticed that master branch images are now almost consistently failing to build with the following error signature if building using multiple build jobs (e.g., SONIC_BUILD_JOBS=20):

 

dpkg: error: dpkg frontend lock is locked by another process

 

I tracked the root cause down to the building of the sonic_yang_mgmt-1.0-py2-none-any.whl package. The problem here is that in your setup.py file, you are explicitly installing .deb packages as build requirements using `dpkg -i` at the following line: https://github.com/Azure/sonic-buildimage/blob/master/src/sonic-yang-mgmt/setup.py#L43

 

However, dpkg cannot handle parallel operations. We encountered this problem before and worked around it by serializing all .deb package installations here: https://github.com/Azure/sonic-buildimage/blob/master/slave.mk#L483. The new issue is caused because the whl package recipe is executed in parallel with the aforementioned serialized .deb package installation recipe.