trace file and analysis ORA 0054

Hi all

I have a little issue according to analysis ORA-000054.

I tried to create a lab  :

I have oracle 12.1.0.2 on AIX 7.1 EE

First off all have altered system to generate trace of ora-0054

ALTER SYSTEM SET EVENTS '54 trace name errorstack level 3';

after that I create table with partitions and subpartition

and now the lab :

1. first session try to insert one row to specific partition and wait without commit

2. second session try to truncate it : 

ALTER TABLE LDS_BASE_DET_STG TRUNCATE SUBPARTITION ("P_506_BEFORE") DROP STORAGE

            *

ERROR at line 1:

ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired