Hanging opatch - Workaround

We have recently run into an issue while patching one of our databases where opatch is hanging and there are no error messages in the logs. 

Debugging revealed that a stale NFS mount point is causing fuser to hang during opatch execution.

Did 'grep -R  fuser $ORACLE_HOME/OPatch' and found below.

[oracle@hostname ~]$ grep -R fuser $ORACLE_HOME/OPatch
/ora01/app/oracle/product/19.3.0.0/OPatch/opatch:#  opatch  02/01/05  Introduce OPATCH_NO_FUSER to bypass fuser check
Binary file /ora01/app/oracle/product/19.3.0.0/OPatch/jre/lib/rt.jar matches
/ora01/app/oracle/product/19.3.0.0/OPatch/docs/Users_Guide.txt:OPatch expects users to have commands such as fuser, ar and make on
/ora01/app/oracle/product/19.3.0.0/OPatch/docs/FAQ:        the path to system commands like 'fuser', 'ar', etc...
/ora01/app/oracle/product/19.3.0.0/OPatch/docs/FAQ:        the required command fuser from Property file and your PATH".
/ora01/app/oracle/product/19.3.0.0/OPatch/docs/FAQ:        fuser is a command used by OPatch. This message may appear if OPatch
/ora01/app/oracle/product/19.3.0.0/OPatch/opatch.bat:REM #  opatch  03/02/05  Introduce OPATCH_NO_FUSER to bypass fuser check

 Issue is resolved after setting below parameter.

export OPATCH_NO_FUSER=true

opatch checks for active files and executables defined in patch inventory.xml using “fuser” command.

 If OPATCH_NO_FUSER is set to true, OPatch will not check if these files defined in executables are busy.