openstack/mistral
Code Issues Proposed changes

Add a release note for graceful scale-in feature

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Change-Id: I9874085555db097c7ae1ae3c2c7cad73b8543ff5
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Renat Akhmerov 2019-12-09 13:00:22 +07:00
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commit d1b8c8bc2c
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releasenotes/notes/mistral-engine-scale-in-bd348f9237f32481.yaml Normal file
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features:
- |
Mistral engine now supports graceful scale-in. That is, if a number of
engines in a cluster needs to be reduced manually it is now possible to
do w/o breaking currently running workflows. In order to shutdown a
Mistral engine, SIGTERM signal needs to be sent to the corresponding
process. In Unix operatating systems it's a matter of running the command
"kill <engine PID>" in any shell. When this signal is caught by the
process, it has a certain amount of time configured by the
'graceful_shutdown_timeout' property to complete currently running
database transactions and process all buffered RPC messages that have
already been polled from the queue. After this time elapses, the process
will be forced to exit.
By default, the value of the 'graceful_shutdown_timeout' property is
60 (seconds).