https://bugzilla.wikimedia.org/show_bug.cgi?id=55929
Web browser: ---
Bug ID: 55929
Summary: Separate replica datacenter causes high query latency
Product: Wikimedia Labs
Version: unspecified
Hardware: All
OS: All
Status: NEW
Severity: major
Priority: Unprioritized
Component: Infrastructure
Assignee: rlan...@gmail.com
Reporter: pathoschild+wmb...@gmail.com
CC: abog...@wikimedia.org, fai...@wikimedia.org
Classification: Unclassified
Mobile Platform: ---
The database replicas are in a different datacenter than Tools Labs. The
resulting latency (26ms per query) has a major performance impact on tools that
need to make many queries. This prevents the migration of many Toolserver tools
(notably crosswiki tools).
This is a tracking ticket for plans to combine the datacenters to address this,
mentioned here:
http://lists.wikimedia.org/pipermail/labs-l/2013-September/001574.html
Repro
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The following scripts reproduce the latency issue. They open a connection to
each database server, then execute a sample query for each wiki ("use
`xxwiki`").
Toolserver: https://toolserver.org/~pathoschild/accounteligibility/test.php |
source: http://pastebin.com/ctUQsXZm
Tools Labs:
http://tools.wmflabs.org/pathoschild-contrib/accounteligibility/test.php |
source: http://pastebin.com/Xi3abGFP
This runs in 0.3 seconds on the Toolserver, but takes a whopping 23 seconds on
Tools Labs. The scripts shows the profiling results at the bottom of the page
(click the [+] next to "Page generated in XX seconds").
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