[New-bugs-announce] [issue34204] Bump the default pickle protocol in shelve

[Serhiy Storchaka]

New submission from Serhiy Storchaka <storchaka+cpython at gmail.com>:

The default pickle protocol is 4 now. But shelve still uses the pickle protocol 3. Shouldn't it be bumped? Shouldn't shelve use pickle.DEFAULT_PROTOCOL by default?

Disadvantages:

1. This will make shelve files incompatible with Python 3.3 by default.

2. Protocol 4 adds 9 bytes of overhead in comparison with protocol 3. This can be too large for the shelve containing a lot of small objects. Maybe strip redundant frame header for small pickles?

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components: Library (Lib)
messages: 322281
nosy: alexandre.vassalotti, lukasz.langa, serhiy.storchaka
priority: normal
severity: normal
status: open
title: Bump the default pickle protocol in shelve
type: enhancement
versions: Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue34204>
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