[New-bugs-announce] [issue6216] Raise Unicode KEEPALIVE_SIZE_LIMIT from 9 to 32?

[Terry J. Reedy]

New submission from Terry J. Reedy <tjreedy at udel.edu>:

>From msg88801
'''
for 3.1: raising the KEEPALIVE_SIZE_LIMIT to 32 as explained and
motivated here:

msg64215

That's a simple non-disruptive change which makes a lot of sense
due to the advances in CPU designs in the last 9 years. I determined
the original value of 9 using benchmarks and similar statistics in
1999/2000.

It's probably also a good time to remove the warning, now that the
implementation has proven itself for so many years...

/* Limit for the Unicode object free list stay alive optimization.

   The implementation will keep allocated Unicode memory intact for
   all objects on the free list having a size less than this
   limit. This reduces malloc() overhead for small Unicode objects.

   At worst this will result in PyUnicode_MAXFREELIST *
   (sizeof(PyUnicodeObject) + KEEPALIVE_SIZE_LIMIT +
   malloc()-overhead) bytes of unused garbage.

   Setting the limit to 0 effectively turns the feature off.

   Note: This is an experimental feature ! If you get core dumps when
   using Unicode objects, turn this feature off.

*/

#define KEEPALIVE_SIZE_LIMIT       9
'''
If this is as non-controversial as it seems, perhaps someone could
change 9 to 32 and remove "Note: This is an experimental feature..." in
time for rc2.

----------
components: Interpreter Core
messages: 88981
nosy: tjreedy
severity: normal
status: open
title: Raise Unicode KEEPALIVE_SIZE_LIMIT from 9 to 32?
type: resource usage
versions: Python 3.1

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