[mythtv-commits] Ticket #10533: Optimize scheduler for duplicate checking and EIT updates

[MythTV]

#10533: Optimize scheduler for duplicate checking and EIT updates
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 Reporter:  gigem                |          Owner:  gigem
     Type:  Developer Task       |         Status:  new
 Priority:  minor                |      Milestone:  0.26
Component:  MythTV - Scheduling  |        Version:  Unspecified
 Severity:  medium               |     Resolution:
 Keywords:                       |  Ticket locked:  0
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Comment (by David Engel <dengel@…>):

 In [changeset:cbb8eb1ee32a658a519d2d5fb751ace114f63bf9/mythtv]:
 {{{
 #!CommitTicketReference repository="mythtv"
 revision="cbb8eb1ee32a658a519d2d5fb751ace114f63bf9"
 Add duplicate checking and limited matching optimizations and other
 scheduler related changes.

 The three major changes are as follows.

 Split the checks against the oldrecorded and recorded tables for
 previous recordings away from the "place" phase of scheduling and call
 it the "check" phase.  This makes it easier to report how much time is
 spent doing this and leads to the next major change.

 Drastically reduce the number of checks against the oldrecorded and
 recorded tables for previous recordings.  Historically, this has been
 the most significant contributor to long scheduler runs.  Not every
 unnecessary check is eliminated, but the vast majority of them are.
 Trying to remove the few remaining ones would probably take longer
 than simply rechecking them.

 Allow for checking a subset of the program table when new guide data
 is available.  This is primarily aimed at EIT scanning where typically
 only a few hours of guide data for specific channels is updated in an
 orderly fashion.  Not rechecking the unchanged guide data greatly
 reduces the amount of work the scheduler has to do.  Please note the
 EIT scanner has not been updated yet to take advantage of this change.

 The other changes are as follows.

 Use more expressive reschedule requests.  This is primarily to support
 the changes listed above.  It also makes it easier to understand why
 reschedules occurred when reading the logs and might lead to the
 elimination of unnecessary reschedules in the future.

   MATCH reschedule requests should be used when the guide data or a
   specific recording rule is changed.  The syntax is as follows.

   RESCHEDULE_RECORDINGS
   MATCH <recordid> <sourceid> <mplexid> <maxstarttime> <reason>

   maxstarttime should be in ISO format.  If recordid, sourceid or
   mplexid are non-zero or maxstarttime is a valid time, the scheduler
   will restrict itself to recording rules and guide data matching
   those parameters.  reason is purely for purposes of logging.

   CHECK reschedule requests should be used when the status of a
   specific episode is affected such as when "never record" or "allow
   re-record" are selected or a recording finishes or is deleted.  The
   syntax is as follows.

   RESCHEDULE_RECORDINGS
   CHECK <recstatus> <recordid> <findid> <reason>
   <title>
   <subtitle>
   <description>
   <programid>

   recordid should be the parent recordid, when applicable, otherwise,
   the normal recordid.  Setting programid to '**any**" and title to ""
   is a special case used to emulate an old reschedule request for
   recordid 0.  Setting programid to "**any**" and title to other than
   "" is another special case used when all entries for a title are
   deleted from oldrecorded.  recstatus and reason are purely for
   purposes of logging.

   PLACE reschedule request should be used in all other cases.  The
   syntax is as follows.

   RESCHEDULE_RECORDINGS
   PLACE <reason>

   reason is purely for purposes of logging.

 Update the PHP and Python bindings to use the new reschedule requests.
 Please note the bindings API has not changed to make full use of the
 new requests.  I'm leaving it to the bindings maintainers to decide
 how best to do that.

 Clear record.duplicate when a recording is queued for deletion.  It
 should have been this way all along and avoids a redundant reschedule
 when the file is actually unlinked.

 Lower the very detailed scheduler placement logging to LOG_DEBUG.
 This makes VB_SCHEDULE/LOG_INFO more useful for less voluminous
 purposes.

 Add findid to the recordmatch table.  This avoids having to calculate
 it in multiple places.

 Tighten the window for rescheduling long running programs from "24
 hours ago" to "~8 hours ago".

 Avoid creating unnecessary RecordingInfo objects that are going to get
 deleted later anyway.

 Fixes #10533
 }}}

-- 
Ticket URL: <http://code.mythtv.org/trac/ticket/10533#comment:1>
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