annotate roundup/anypy/dbm_.py @ 6565:2c2dbfc332ba

Try to handle multiple connections better. The session database is a hot spot. When multiple requests (e.g. 20) come in at the same time session database contention can get great. The original code didn't retry session database access when the open failed. This resulted in errors at the client. The second pass delayed 0.01 seconds and retried. It was better but we still had multiple second stalls. I think the first request got in, everybody else backed up and then retried at the same time. Again they stepped on each other. With logging I would see many counters go all the way to low single digits or to -1 indicating falure. This pass uses randomint to generate delays from 0-.125 seconds in 5ms increments. This performs better in testing. I rarely saw a counter less than 13 (2 failed retries). Current logging starts after 6 failures and counts down until success or failure.
author John Rouillard <rouilj@ieee.org>
date Thu, 16 Dec 2021 20:02:00 -0500
parents d5da643b3d25
children
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Richard Jones <richard@users.sourceforge.net>
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1 # In Python 3 the "anydbm" module was renamed to be "dbm" which is now a
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2 # package containing the various implementations. The "wichdb" module's
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3 # whichdb() function was moved to the new "dbm" module.
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4
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5 try:
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6 # old school first because <3 had a "dbm" module too...
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7 import anydbm
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8 from whichdb import whichdb
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9 except ImportError:
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10 # python 3+
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11 import dbm as anydbm
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12 whichdb = anydbm.whichdb

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