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[Bug 1580534] Re: Signature verification is too slow

To: group.of.nepali.translators@xxxxxxxxxxxxxxxxxxx
From: Launchpad Bug Tracker <1580534@xxxxxxxxxxxxxxxxxx>
Date: Wed, 15 Jun 2016 05:42:06 -0000
Reply-to: Bug 1580534 <1580534@xxxxxxxxxxxxxxxxxx>
Sender: bounces@xxxxxxxxxxxxx

This bug was fixed in the package simplestreams -
0.1.0~bzr426-0ubuntu1.1

---------------
simplestreams (0.1.0~bzr426-0ubuntu1.1) xenial; urgency=medium

  * Fix signature verification speed (LP: #1580534).

 -- Robie Basak <robie.basak@xxxxxxxxxx>  Thu, 12 May 2016 17:43:07
+0000

** Changed in: simplestreams (Ubuntu Xenial)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1580534

Title:
  Signature verification is too slow

Status in simplestreams:
  Fix Committed
Status in simplestreams package in Ubuntu:
  Fix Released
Status in simplestreams source package in Xenial:
  Fix Released

Bug description:
  [Impact]

  When running against http://cloud-
  images.ubuntu.com/releases/streams/v1/com.ubuntu.cloud:released:download.sjson,
  read_signed() in simplestreams/utils.py seems to take minutes (402
  seconds in my instrumented timing) running 100% CPU. At the time of my
  test, download.sjson is 451737 bytes in 1870 lines.

  This makes a uvtool sync virtually unusable on Xenial.

  [Development Fix]

  The culprit is the constant += of a string as it is read in. This is
  inefficient in Python as each += results in a new string that has to
  be allocated. Keeping the lines in a list and joining them at the end
  reduces the time to 0.127 seconds.

  [Stable Fix]

  No change cherry-pick of fix committed upstream.

  [Test Case]

  On a machine with reasonable connectivity, run: uvt-simplestreams-
  libvirt sync release=xenial arch=amd64

  Expected result: takes a few seconds with minimal CPU use.

  Actual result: takes more than five minutes with CPU pegged at 100%.

  Scott also has a more direct test case here:
  http://paste.ubuntu.com/16377613/

  [Original Notes]

  Merge proposal to follow. I'm filing this bug to track a Xenial SRU.

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