Zend certified PHP/Magento developer

Do shell pipes block upstream source processes if the buffer is overflowing?

I do various sysadmin tasks to clean up my disks, such as (but not limited to):

find /media/me/disk_with_huge_inode_count -type d -empty | xargs rmdir -p

and the rmdir part is really slow, while find produces a huge amount of output by comparison. What will be the behaviour of the find under such a scenario?

I’m not looking for specific advice for this operation because I have this concern with other similar jobs. What I want to understand is how the Linux kernel (or shell?) handles pipeline overflows when the producer and consumer have a load mismatch.