pkg-stats currently uses the services from support/scripts/cpedb.py to
match the CPE identifiers of packages with the official CPE database.
Unfortunately, the cpedb.py code uses regular ElementTree parsing,
which involves loading the full XML tree into memory. This causes the
pkg-stats process to consume a huge amount of memory:
thomas 1310458 85.2 21.4 3708952 3450164 pts/5 R+ 16:04 0:33 | | \_ python3 ./support/scripts/pkg-stats
So, 3.7 GB of VSZ and 3.4 GB of RSS are used by the pkg-stats
process. This is causing the OOM killer to kick-in on machines with
relatively low memory.
This commit reimplements the XML parsing needed to do the CPE matching
directly in pkg-stats, using the XmlParser functionality of
ElementTree, also called "streaming parsing". Thanks to this, we never
load the entire XML tree in RAM, but only stream it through the
parser, and construct a very simple list of all CPE identifiers. The
max memory consumption of pkg-stats is now:
thomas 1317511 74.2 0.9 381104 152224 pts/5 R+ 16:08 0:17 | | \_ python3 ./support/scripts/pkg-stats
So, 381 MB of VSZ and 152 MB of RSS, which is obviously much better.
The JSON output of pkg-stats for the full package set, before and after
this commit, is exactly identical.
Now, one will probably wonder why this isn't directly changed in
cpedb.py. The reason is simple: cpedb.py is also used by
support/scripts/missing-cpe, which (for now) heavily relies on having
in memory the ElementTree objects, to re-generate a snippet of XML
that allows us to submit to NIST new CPE entries.
So, future work could include one of those two options:
(1) Re-integrate cpedb.py into missing-cpe directly, and live with
two different ways of processing the CPE database.
(2) Rewrite the missing-cpe logic to also be compatible with a
streaming parsing, which would allow this logic to be again
shared between pkg-stats and missing-cpe.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
[yann.morin.1998@free.fr:
- add missing import of requests
- import CPEDB_URL from cpedb, instead of duplicating it
- fix flake8 errors
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
bd1798ad95