Subject Re: [firebird-support] Re: FB 2.1 CS High FBLockPrint Mutex wait figure
Author Steve Wiser
Post date 2015-06-17T14:46:20Z
I am also curious as to why you are seeing such high mutex wait percentages and would love to see some responses.

During load testing of one of our systems we noticed the same thing, by migrating the test environment to SuperClassic 2.5.4 we were able to get better throughput over Classic 2.1.5 (we run on CentOS, 64-bit).  With the upgrade we are still seeing high mutex wait percentages though -- so far we have just chalked it up to a lot of queries hitting the same table and are now tuning our caching layer.

-steve


On Tue, Jun 16, 2015 at 6:30 AM, 'Neil Pickles' neil.pickles@... [firebird-support] <firebird-support@yahoogroups.com> wrote:
 

Thanks Dmitry.

This server was last restarted about 12 hours ago.

Non standard firebird.conf entries are:-

DefaultDbCachePages = 384
TempBlockSize = 2048576
TempCacheLimit = 77108864
LockMemSize = 26214400
LockHashSlots = 30011

Gstat -h output for database 1

Database "/home/ssddata/headoffice.fdb"
Database header page information:
Flags 0
Checksum 12345
Generation 72934754
Page size 4096
ODS version 11.1
Oldest transaction 61782471
Oldest active 61782472
Oldest snapshot 61782472
Next transaction 61822410
Bumped transaction 1
Sequence number 0
Next attachment ID 11112276
Implementation ID 24
Shadow count 0
Page buffers 0
Next header page 0
Database dialect 3
Creation date Feb 13, 2014 21:50:31
Attributes force write

Variable header data:
Sweep interval: 20000
*END*

Gstat -h output for database 2

Database "/home/ssddata/historyv2.fdb"
Database header page information:
Flags 0
Checksum 12345
Generation 9215513
Page size 4096
ODS version 11.1
Oldest transaction 9093765
Oldest active 9093766
Oldest snapshot 9093766
Next transaction 9093767
Bumped transaction 1
Sequence number 0
Next attachment ID 121715
Implementation ID 24
Shadow count 0
Page buffers 0
Next header page 0
Database dialect 3
Creation date Jan 5, 2014 20:15:22
Attributes force write

Variable header data:
Sweep interval: 20000
*END*

Fblockprint header info, I have attached the full file if you need more
info.

LOCK_HEADER BLOCK
Version: 144, Active owner: 0, Length: 26214400, Used:
2166784
Lock manager pid: 1317
Semmask: 0x3DBA0, Flags: 0x0001
Enqs: 1569899326, Converts: 448147, Rejects: 54828, Blocks:
296140
Deadlock scans: 0, Deadlocks: 0, Scan interval: 10
Acquires: 1582875314, Acquire blocks: 701565622, Spin count: 0
Mutex wait: 44.3%
Hash slots: 30011, Hash lengths (min/avg/max): 0/ 0/ 16
Remove node: 0, Insert queue: 0, Insert prior: 0
Owners (23): forward: 253088, backward: 1569408
Free owners (5): forward: 745920, backward: 1302520
Free locks (3233): forward: 2067728, backward: 811520
Free requests (3470): forward: 1993640, backward: 915264
Lock Ordering: Enabled

Cheers,

Neil Pickles - neil@...

 CSY Retail Systems Limited

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