I'm trying to export a large CSV file (150,000 lines) using a batch apex and put the file in a FTP.
When it is about 100,000 lines it throws a heap limit exception.

What could be the best alternative to export a CSV and put it in a FTP folder?

I have created a canvas on customer community portal.
When the user is interacting just with the canvased app for a time that elapses defined session timeout, when the user click in another Tab, the user gets a timeout error.
Is this the expected behavior? If yes, what should be an advisable solution?

I'm trying to export a large CSV file (150,000 lines) using a batch apex and put the file in a FTP.
When it is about 100,000 lines it throws a heap limit exception.

What could be the best alternative to export a CSV and put it in a FTP folder?