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High mutex wait ratio and degraded performance after some time of performing normally [CORE2591] #3001

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firebird-issue-importer opened this issue Aug 13, 2009 · 8 comments

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@firebird-issue-importer

Submitted by: @dyemanov

When the system is highly loaded for a long time, some operations may perform worse as compared to a recently restarted server (and the lock manager). This situation is coupled with a unexpectedly high mutex wait ratio in the fb_lock_print output.

The lock table has many double linked lists that represent the various run-time objects: resources, requests, owners, etc. All operations with these lists are usually very fast (complexity O(1)), but allocation of a new lock resource requires scanning the total list of unused locks in order to find a best match for the given lock key size. This raises the complexity up to O(N) in the worst case. Recent FB versions have introduced more locks per server process, e.g. DSQL cache locks and index page GC locks, thus increasing the total number of locks in the lock table as well as the average number of unused locks in the list. So this issue becomes more visible nowadays.

Commits: e5a70ba 3a278cf 3f6dd2b

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@firebird-issue-importer firebird-issue-importer commented Aug 13, 2009

Modified by: @dyemanov

assignee: Dmitry Yemanov [ dimitr ]

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@firebird-issue-importer firebird-issue-importer commented Aug 13, 2009

Modified by: @dyemanov

status: Open [ 1 ] => In Progress [ 3 ]

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@firebird-issue-importer firebird-issue-importer commented Aug 13, 2009

Modified by: @dyemanov

status: In Progress [ 3 ] => Open [ 1 ]

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@firebird-issue-importer firebird-issue-importer commented Aug 13, 2009

Modified by: @dyemanov

status: Open [ 1 ] => Resolved [ 5 ]

resolution: Fixed [ 1 ]

Fix Version: 2.5 RC1 [ 10362 ]

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@firebird-issue-importer firebird-issue-importer commented Aug 13, 2009

Modified by: @dyemanov

Fix Version: 2.1.4 [ 10361 ]

Fix Version: 2.0.6 [ 10303 ]

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@firebird-issue-importer firebird-issue-importer commented Nov 12, 2009

Modified by: @pcisar

status: Resolved [ 5 ] => Closed [ 6 ]

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@firebird-issue-importer firebird-issue-importer commented Jan 18, 2016

Modified by: @pavel-zotov

QA Status: No test

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@firebird-issue-importer firebird-issue-importer commented Aug 7, 2016

Modified by: @pavel-zotov

status: Closed [ 6 ] => Closed [ 6 ]

QA Status: No test => Cannot be tested

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