[tahoe-lafs-trac-stream] [tahoe-lafs] #1392: if you have fewer than 1000 measurements, return None (meaning "I don't know") when asked for the 99.9% percentile.

tahoe-lafs trac at tahoe-lafs.org
Tue Apr 26 14:07:03 PDT 2011


#1392: if you have fewer than 1000 measurements, return None (meaning "I don't
know") when asked for the 99.9% percentile.
-------------------------------+----------------------------------
     Reporter:  arch_o_median  |      Owner:  arch_o_median
         Type:  defect         |     Status:  new
     Priority:  minor          |  Milestone:  undecided
    Component:  code-storage   |    Version:  1.8.2
   Resolution:                 |   Keywords:  design-review-needed
Launchpad Bug:                 |
-------------------------------+----------------------------------

Comment (by zooko):

 arch_o_median will do the "finding all consumers" part. There are two
 types of consumers:
 * those that invoke the Python API, i.e. any Python code that invokes
 [source:trunk/src/allmydata/storage/server.py?annotate=blame&rev=4895#L153
 get_stats()] or
 [source:trunk/src/allmydata/storage/server.py?annotate=blame&rev=4895
 get_latencies()]
 * those that use the WUI/WAPI, i.e. any HTTP clients that are reading the
 HTTP results rendered by
 [source:trunk/src/allmydata/web/storage.py?annotate=blame&rev=4229#L28
 web.storage.StorageStatus.render_JSON()] or
 [source:trunk/src/allmydata/web/storage.py?annotate=blame&rev=4229#L56 the
 "stats" magic Nevow variable]. Looking at [source:trunk/docs/stats.rst
 #statistics-categories stats.rst], it appears that only code that is
 looking for the key {{{latencies}}} in the resulting stats dict could be
 affected. Grepping for {{{latencies}}} in the Tahoe-LAFS code base, I see
 that
 [source:trunk/misc/operations_helpers/munin/tahoe_server_latency_?annotate=blame&rev=4434
 misc/operations_helpers/munin/tahoe_server_latency_] is the only such in
 our source tree. There is documentation about the Munin plugins in
 [source:trunk/docs/stats.rst#using-munin-to-graph-stats-values stats.rst],
 and also at the top of the munin/tahoe_server_latency_ file.

-- 
Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1392#comment:16>
tahoe-lafs <http://tahoe-lafs.org>
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