#11729: Cache module import locations
---------------------------+------------------------------------------------
Reporter: vbraun | Owner: jason
Type: enhancement | Status: new
Priority: major | Milestone: sage-4.7.2
Component: misc | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author: Volker Braun
Merged: | Dependencies:
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Description changed by vbraun:
Old description:
> This ticket implements a cached module importer for Python. It hooks into
> the Python import framework and caches whether a module was found and if
> so, its location. The cache is persistent over sessions.
>
> Except for the location of the persistent storage (in
> `DOT_SAGE/import_cache.txt`) there is no dependency on Sage.
>
> By default, the cached importer is not active. To activate it on your
> system, you have to import the module at one point in the Python startup,
> preferably as early as possible. The easiest way to do so is to create a
> file `$SAGE_LOCAL/lib/python/site-packages/sitecustomize.py` containing
> the single line
> {{{
> import sage.misc.importer
> }}}
>
> Some benchmarks:
> {{{
> #!sh
>
> }}}
New description:
This ticket implements a cached module importer for Python. It hooks into
the Python import framework and caches whether a module was found and if
so, its location. The cache is persistent over sessions.
Except for the location of the persistent storage (in
`$DOT_SAGE/import_cache.txt`) there is no dependency on Sage.
By default, the cached importer is not active. To activate it on your
system, you have to import the module at one point in the Python startup,
preferably as early as possible. The easiest way to do so is to create a
file `$SAGE_LOCAL/lib/python/site-packages/sitecustomize.py` containing
the single line
{{{
import sage.misc.importer
}}}
Some benchmarks:
{{{
#!sh
[vbraun@volker-laptop-two ~]$ rm ~/.sage/import_cache.txt
[vbraun@volker-laptop-two ~]$ strace -e file -f sage -c quit |& grep
ENOENT | wc
20173 243630 3085872
[vbraun@volker-laptop-two ~]$ strace -e file -f sage -c quit |& grep
ENOENT | wc
2276 28856 258830
[vbraun@volker-laptop-two ~]$ strace -e file -f sage -c quit |& grep
ENOENT | wc
2276 28905 257473
}}}
Sage-4.7.2.alpha1 startuptime on my laptop decreased from 0.89s to 0.78s
with the cached importer.
Note: at this point you should erase the `import_cache.txt` before and
after rebuilding the sage library. In the future, we might introduce
timestamps for the cache to be erased automatically if it is obsolete.
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11729#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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