WIP: Fix tmp files

[Phu2]

1. remove temp files
2. restrict size of files

Re 1: already tested successfully using https://test.metafacture.org/playground/?flux=%22https%3A//duepublico2.uni-due.de/oer/oai%22%0A%7C+open-oaipmh%28metadataPrefix%3D%22mods%22%29%0A%7C+decode-xml%0A%7C+handle-generic-xml%0A%7C+encode-json%28prettyPrinting%3D%22true%22%29%0A%7C+write%28%22text.json%22%29%3B%0A

Re 2: testing tbd

[Phu2]

Unfortunately 4bf31e7 does not prevent the behavior described in #159 (comment)

This big JSON file was created by processing a specific OAI endpoint with >50k records. I can reproduce this behavior with this same endpoint. Lots of requests (per resumptionToken) are being made while the result file is still empty. At some point in time the requests come to a halt and the result file is written very fast.

[TobiasNx]

Unfortunately 4bf31e7 does not prevent the behavior described in #159 (comment)

This big JSON file was created by processing a specific OAI endpoint with >50k records. I can reproduce this behavior with this same endpoint. Lots of requests (per resumptionToken) are being made while the result file is still empty. At some point in time the requests come to a halt and the result file is written very fast.

I assume that the oaipmh opener does not stream data through but buffer until all data is fetched, @dr0i can you confirm this?