Can we run pg_basebackup master is still working normally (selects, updates, deleted, etc)

[Adrian Heath <adrian.heath@xxxxxxxxxxxxxx>]

We have master/standby servers running postgresql 9.6.5 on Debian 8.0 
(Wheezy) 64 bit and we want to add a 3rd machine, streaming from the 
master but running off-site.

The system is used 24/7. Can we run pg_basebackup while the master is 
still receiving updates without worrying about physical file corruptions 
in the generated archive file?

 The documentation states that v9.6 supports running concurrent 
backups. Can the users operate as normal, ie issue 
inserts/deletes/updates, while the file copy is occurring? We can pick a 
time when the system is quieter but there is always something/someone 
updating the system.