subprocess.Popen: does not return complete output , when run through crontab

[kintul]

I am calling some java binary in unix environment wrapped inside python script

When I call script from bash, output comes clean and also being stored in desired variable , However when i run the same script from Cron, Output stored(in a Variable) is incomplete

my code:

command = '/opt/HP/BSM/PMDB/bin/abcAdminUtil -abort -streamId ETL_' \
          'SystemManagement_PA@Fact_SCOPE_OVPAGlobal'
proc = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE, 
                       stderr=subprocess.PIPE)
(output, err) = proc.communicate() # Storing Output in output variable

Value of output variable when running from shell:

Abort cmd output:PID:8717
Executing abort function
hibernateConfigurationFile = /OBRHA/HPE-OBR/PMDB/lib/hibernate-core-4.3.8.Final.jar
Starting to Abort Stream ETL_SystemManagement_PA@Fact_SCOPE_OVPAGlobal
Aborting StreamETL_SystemManagement_PA@Fact_SCOPE_OVPAGlobal

Value of output variable when running from cron:

PID:830

It seems output after creating new process is not being stored into variable , i don't know why ?