expdp Hangs at DATABASE_EXPORT/SYSTEM_PROCOBJACT/POST_SYSTEM_ACTIONS/PROCACT_SYSTEM in oracle 12c Expdp Hangs at Below Stage for long time even in structure backup also .

Processing object type DATABASE_EXPORT/SYSTEM_PROCOBJACT/PRE_SYSTEM_ACTIONS/PROCACT_SYSTEM
Processing object type DATABASE_EXPORT/SYSTEM_PROCOBJACT/PROCOBJ
Processing object type DATABASE_EXPORT/SYSTEM_PROCOBJACT/POST_SYSTEM_ACTIONS/PROCACT_SYSTEM


Database Version: -Oracle Database 12c Standard Edition Release 12.2.0.1.0 - 64bit Production

so please let me know to get solution &amp; if it is 12c Bug then please mention bug number also 

P.S :-
here is expdp full script 

 expdp username/password full=Y CONTENT=METADATA_ONLY directory=DIR1 dumpfile=structure_backup.dmp logfile=structure_backup.log KEEP_MASTER=Y


Database Size :- 10 GB
So in the end it's just a time issue you have. You would have to open up a ticket with Oracle if you want to speed things up. This is probably not an Oracle issue, but possibly an issue with your database design.

You have to understand that the Data Pump Export Utility has to determine all relevant constraints and relations before it can create a valid structured metadata export. This can take a substantial amount of time and depends on the structure of your database, the amount of schemas and other limiting constraints.

The more complex the metadata is, the longer it can take to export.

You might want to look at the object after the .../POST_SYSTEM_ACTIONS/PROCACT_SYSTEM as that could actually be the limiting factor. 

You might want to have a look at the official documentation regarding Database Utilities | Data Pump Performance | Tuning Performance (Oracle 12c Documentation) for additional ideas on how to speed up things.