• self.env.cr.commit() commits the transaction's buffered write operations.
• self.env.cr.savepoint() sets a transaction savepoint to rollback to.
• self.env.cr.rollback() cancels the transaction's write operations since the last commit, or all if no commit was done.

commit the code by 

self.env.cr.commit()

If you have too many records in for loop then commit every 100 or 1000th record

count += 1
if count == 100:
_logger.info('100 records created ')
self.env.cr.commit()
count = 0

add this to py file
#top of the file
from odoo import api, fields, models, _, modules
from odoo.http import request
#before for loop
r = modules.registry.RegistryManager.get(dbname)
cr = r.cursor()
#inside loop
cr.commit()
#make sure you close cr at the end of the function scope
cr.close()

Let me know if there is any error with your log file