Details
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Bug
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Status: Closed (View Workflow)
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Minor
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Resolution: Incomplete
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2.4.9
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None
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RHEL7
3 nodes Percona XtraDB Cluster & MaxScale
Description
It's possible that two threads can both pick the same server when one of the threads should pick another server. This happens because the server selection process doesn't try to repeat the selection process if another thread manages to increment the counter before it. In the end this will cause transient small imbalances in the connection counts between servers.
Original description:
Hi,
I have found some strange thing with V 2.4 in synced mode.
If I try a sysbench by example with 15 thread, normally, the connections are splitted by the numbers of nodes (so 5 co by node in this context).
Cf conf:
[root@router ~]# cat /etc/maxscale.cnf
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[maxscale]
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threads=auto
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[dbserv1]
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type=server
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address=192.168.116.111
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port=3306
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protocol=MariaDBBackend
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[dbserv2]
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type=server
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address=192.168.116.112
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port=3306
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protocol=MariaDBBackend
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[dbserv3]
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type=server
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address=192.168.116.113
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port=3306
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protocol=MariaDBBackend
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[Galera-Monitor]
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type=monitor
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module=galeramon
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servers=dbserv1, dbserv2, dbserv3
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user=monitor_user
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passwd=my_password
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monitor_interval=2000
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[Galera-Service]
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type=service
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router=readconnroute
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router_options=synced
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servers=dbserv1, dbserv2, dbserv3
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user=maxscale
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passwd=maxscale_pw
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[Galera-Listener]
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type=listener
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service=Galera-Service
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protocol=MariaDBClient
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port=4306
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Once I launch maxctrl list servers:
│ dbserv1 │ dbserv1 │ 3306 │ 7 │ Slave, Synced, Running │ │
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├──────────────┼────────────────────────────┼──────┼─────────────┼─────────────────────────┼──────┤
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│ dbserv2 │ dbserv2 │ 3306 │ 4 │ Master, Synced, Running │ │
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├──────────────┼────────────────────────────┼──────┼─────────────┼─────────────────────────┼──────┤
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│ dbserv3 │ dbserv3 │ 3306 │ 4 │ Slave, Synced, Running │ │
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Why the traffic is not splitted by 3 on each node?
Best regards,